Users can apply multiple suggestions at once.

app/assets/javascripts/api.js

@@ -38,6 +38,7 @@ const Api = {
   userPostStatusPath: '/api/:version/user/status',
   commitPath: '/api/:version/projects/:id/repository/commits',
   applySuggestionPath: '/api/:version/suggestions/:id/apply',
+  applySuggestionBatchPath: '/api/:version/suggestions/batch_apply',
   commitPipelinesPath: '/:project_id/commit/:sha/pipelines',
   branchSinglePath: '/api/:version/projects/:id/repository/branches/:branch',
   createBranchPath: '/api/:version/projects/:id/repository/branches',
@@ -322,6 +323,12 @@ const Api = {
     return axios.put(url);
   },
 
+  applySuggestionBatch(ids) {
+    const url = Api.buildUrl(Api.applySuggestionBatchPath);
+
+    return axios.put(url, { ids });
+  },
+
   commitPipelines(projectId, sha) {
     const encodedProjectId = projectId
       .split('/')

app/assets/javascripts/notes/components/note_body.vue

 <script>
-import { mapActions, mapGetters } from 'vuex';
+import { mapActions, mapGetters, mapState } from 'vuex';
 import $ from 'jquery';
 import '~/behaviors/markdown/render_gfm';
 import noteEditedText from './note_edited_text.vue';
@@ -50,6 +50,9 @@ export default {
 
       return this.getDiscussion(this.note.discussion_id);
     },
+    ...mapState({
+      batchSuggestionsInfo: state => state.notes.batchSuggestionsInfo,
+    }),
     noteBody() {
       return this.note.note;
     },
@@ -79,7 +82,12 @@ export default {
     }
   },
   methods: {
-    ...mapActions(['submitSuggestion']),
+    ...mapActions([
+      'submitSuggestion',
+      'submitSuggestionBatch',
+      'addSuggestionInfoToBatch',
+      'removeSuggestionInfoFromBatch',
+    ]),
     renderGFM() {
       $(this.$refs['note-body']).renderGFM();
     },
@@ -96,6 +104,17 @@ export default {
         callback,
       );
     },
+    applySuggestionBatch({ flashContainer }) {
+      return this.submitSuggestionBatch({ flashContainer });
+    },
+    addSuggestionToBatch(suggestionId) {
+      const { discussion_id: discussionId, id: noteId } = this.note;
+
+      this.addSuggestionInfoToBatch({ suggestionId, discussionId, noteId });
+    },
+    removeSuggestionFromBatch(suggestionId) {
+      this.removeSuggestionInfoFromBatch(suggestionId);
+    },
   },
 };
 </script>
@@ -105,10 +124,14 @@ export default {
     <suggestions
       v-if="hasSuggestion && !isEditing"
       :suggestions="note.suggestions"
+      :batch-suggestions-info="batchSuggestionsInfo"
       :note-html="note.note_html"
       :line-type="lineType"
       :help-page-path="helpPagePath"
       @apply="applySuggestion"
+      @applyBatch="applySuggestionBatch"
+      @addToBatch="addSuggestionToBatch"
+      @removeFromBatch="removeSuggestionFromBatch"
     />
     <div v-else class="note-text md" v-html="note.note_html"></div>
     <note-form

app/assets/javascripts/notes/stores/actions.js

@@ -524,12 +524,55 @@ export const submitSuggestion = (
       const defaultMessage = __(
         'Something went wrong while applying the suggestion. Please try again.',
       );
-      const flashMessage = err.response.data ? `${err.response.data.message}.` : defaultMessage;
+
+      const errorMessage = err.response.data?.message;
+
+      const flashMessage = errorMessage || defaultMessage;
 
       Flash(__(flashMessage), 'alert', flashContainer);
     });
 };
 
+export const submitSuggestionBatch = ({ commit, dispatch, state }, { flashContainer }) => {
+  const suggestionIds = state.batchSuggestionsInfo.map(({ suggestionId }) => suggestionId);
+
+  const applyAllSuggestions = () =>
+    state.batchSuggestionsInfo.map(suggestionInfo =>
+      commit(types.APPLY_SUGGESTION, suggestionInfo),
+    );
+
+  const resolveAllDiscussions = () =>
+    state.batchSuggestionsInfo.map(suggestionInfo => {
+      const { discussionId } = suggestionInfo;
+      return dispatch('resolveDiscussion', { discussionId }).catch(() => {});
+    });
+
+  commit(types.SET_APPLYING_BATCH_STATE, true);
+
+  return Api.applySuggestionBatch(suggestionIds)
+    .then(() => Promise.all(applyAllSuggestions()))
+    .then(() => Promise.all(resolveAllDiscussions()))
+    .then(() => commit(types.CLEAR_SUGGESTION_BATCH))
+    .catch(err => {
+      const defaultMessage = __(
+        'Something went wrong while applying the batch of suggestions. Please try again.',
+      );
+
+      const errorMessage = err.response.data?.message;
+
+      const flashMessage = errorMessage || defaultMessage;
+
+      Flash(__(flashMessage), 'alert', flashContainer);
+    })
+    .finally(() => commit(types.SET_APPLYING_BATCH_STATE, false));
+};
+
+export const addSuggestionInfoToBatch = ({ commit }, { suggestionId, noteId, discussionId }) =>
+  commit(types.ADD_SUGGESTION_TO_BATCH, { suggestionId, noteId, discussionId });
+
+export const removeSuggestionInfoFromBatch = ({ commit }, suggestionId) =>
+  commit(types.REMOVE_SUGGESTION_FROM_BATCH, suggestionId);
+
 export const convertToDiscussion = ({ commit }, noteId) =>
   commit(types.CONVERT_TO_DISCUSSION, noteId);
 

app/assets/javascripts/notes/stores/modules/index.js

@@ -11,6 +11,7 @@ export default () => ({
     targetNoteHash: null,
     lastFetchedAt: null,
     currentDiscussionId: null,
+    batchSuggestionsInfo: [],
 
     // View layer
     isToggleStateButtonLoading: false,

app/assets/javascripts/notes/stores/mutation_types.js

@@ -17,6 +17,10 @@ export const SET_NOTES_FETCHED_STATE = 'SET_NOTES_FETCHED_STATE';
 export const SET_NOTES_LOADING_STATE = 'SET_NOTES_LOADING_STATE';
 export const DISABLE_COMMENTS = 'DISABLE_COMMENTS';
 export const APPLY_SUGGESTION = 'APPLY_SUGGESTION';
+export const SET_APPLYING_BATCH_STATE = 'SET_APPLYING_BATCH_STATE';
+export const ADD_SUGGESTION_TO_BATCH = 'ADD_SUGGESTION_TO_BATCH';
+export const REMOVE_SUGGESTION_FROM_BATCH = 'REMOVE_SUGGESTION_FROM_BATCH';
+export const CLEAR_SUGGESTION_BATCH = 'CLEAR_SUGGESTION_BATCH';
 export const CONVERT_TO_DISCUSSION = 'CONVERT_TO_DISCUSSION';
 export const REMOVE_CONVERTED_DISCUSSION = 'REMOVE_CONVERTED_DISCUSSION';
 

app/assets/javascripts/notes/stores/mutations.js

@@ -225,6 +225,39 @@ export default {
     }));
   },
 
+  [types.SET_APPLYING_BATCH_STATE](state, isApplyingBatch) {
+    state.batchSuggestionsInfo.forEach(suggestionInfo => {
+      const { discussionId, noteId, suggestionId } = suggestionInfo;
+
+      const noteObj = utils.findNoteObjectById(state.discussions, discussionId);
+      const comment = utils.findNoteObjectById(noteObj.notes, noteId);
+
+      comment.suggestions = comment.suggestions.map(suggestion => ({
+        ...suggestion,
+        is_applying_batch: suggestion.id === suggestionId && isApplyingBatch,
+      }));
+    });
+  },
+
+  [types.ADD_SUGGESTION_TO_BATCH](state, { noteId, discussionId, suggestionId }) {
+    state.batchSuggestionsInfo.push({
+      suggestionId,
+      noteId,
+      discussionId,
+    });
+  },
+
+  [types.REMOVE_SUGGESTION_FROM_BATCH](state, id) {
+    const index = state.batchSuggestionsInfo.findIndex(({ suggestionId }) => suggestionId === id);
+    if (index !== -1) {
+      state.batchSuggestionsInfo.splice(index, 1);
+    }
+  },
+
+  [types.CLEAR_SUGGESTION_BATCH](state) {
+    state.batchSuggestionsInfo.splice(0, state.batchSuggestionsInfo.length);
+  },
+
   [types.UPDATE_DISCUSSION](state, noteData) {
     const note = noteData;
     const selectedDiscussion = state.discussions.find(disc => disc.id === note.id);

app/assets/javascripts/vue_shared/components/markdown/suggestion_diff.vue

@@ -13,6 +13,11 @@ export default {
       type: Object,
       required: true,
     },
+    batchSuggestionsInfo: {
+      type: Array,
+      required: false,
+      default: () => [],
+    },
     disabled: {
       type: Boolean,
       required: false,
@@ -24,6 +29,14 @@ export default {
     },
   },
   computed: {
+    batchSuggestionsCount() {
+      return this.batchSuggestionsInfo.length;
+    },
+    isBatched() {
+      return Boolean(
+        this.batchSuggestionsInfo.find(({ suggestionId }) => suggestionId === this.suggestion.id),
+      );
+    },
     lines() {
       return selectDiffLines(this.suggestion.diff_lines);
     },
@@ -32,6 +45,15 @@ export default {
     applySuggestion(callback) {
       this.$emit('apply', { suggestionId: this.suggestion.id, callback });
     },
+    applySuggestionBatch() {
+      this.$emit('applyBatch');
+    },
+    addSuggestionToBatch() {
+      this.$emit('addToBatch', this.suggestion.id);
+    },
+    removeSuggestionFromBatch() {
+      this.$emit('removeFromBatch', this.suggestion.id);
+    },
   },
 };
 </script>
@@ -42,8 +64,14 @@ export default {
       class="qa-suggestion-diff-header js-suggestion-diff-header"
       :can-apply="suggestion.appliable && suggestion.current_user.can_apply && !disabled"
       :is-applied="suggestion.applied"
+      :is-batched="isBatched"
+      :is-applying-batch="suggestion.is_applying_batch"
+      :batch-suggestions-count="batchSuggestionsCount"
       :help-page-path="helpPagePath"
       @apply="applySuggestion"
+      @applyBatch="applySuggestionBatch"
+      @addToBatch="addSuggestionToBatch"
+      @removeFromBatch="removeSuggestionFromBatch"
     />
     <table class="mb-3 md-suggestion-diff js-syntax-highlight code">
       <tbody>

app/assets/javascripts/vue_shared/components/markdown/suggestion_diff_header.vue

 <script>
 import { GlDeprecatedButton, GlLoadingIcon, GlTooltipDirective } from '@gitlab/ui';
 import Icon from '~/vue_shared/components/icon.vue';
+import { __ } from '~/locale';
 
 export default {
   components: { Icon, GlDeprecatedButton, GlLoadingIcon },
   directives: { 'gl-tooltip': GlTooltipDirective },
   props: {
+    batchSuggestionsCount: {
+      type: Number,
+      required: false,
+      default: 0,
+    },
     canApply: {
       type: Boolean,
       required: false,
@@ -16,6 +22,16 @@ export default {
       required: true,
       default: false,
     },
+    isBatched: {
+      type: Boolean,
+      required: false,
+      default: false,
+    },
+    isApplyingBatch: {
+      type: Boolean,
+      required: false,
+      default: false,
+    },
     helpPagePath: {
       type: String,
       required: true,
@@ -23,17 +39,38 @@ export default {
   },
   data() {
     return {
-      isApplying: false,
+      isApplyingSingle: false,
     };
   },
+  computed: {
+    isApplying() {
+      return this.isApplyingSingle || this.isApplyingBatch;
+    },
+    applyingSuggestionsMessage() {
+      if (this.isApplyingSingle || this.batchSuggestionsCount < 2) {
+        return __('Applying suggestion...');
+      }
+      return __('Applying suggestions...');
+    },
+  },
   methods: {
     applySuggestion() {
       if (!this.canApply) return;
-      this.isApplying = true;
+      this.isApplyingSingle = true;
       this.$emit('apply', this.applySuggestionCallback);
     },
     applySuggestionCallback() {
-      this.isApplying = false;
+      this.isApplyingSingle = false;
+    },
+    applySuggestionBatch() {
+      if (!this.canApply) return;
+      this.$emit('applyBatch');
+    },
+    addSuggestionToBatch() {
+      this.$emit('addToBatch');
+    },
+    removeSuggestionFromBatch() {
+      this.$emit('removeFromBatch');
     },
   },
 };
@@ -47,15 +84,43 @@ export default {
         <icon name="question-o" css-classes="link-highlight" />
       </a>
     </div>
-    <span v-if="isApplied" class="badge badge-success">{{ __('Applied') }}</span>
-    <div v-if="isApplying" class="d-flex align-items-center text-secondary">
+    <div v-if="isApplied" class="badge badge-success">{{ __('Applied') }}</div>
+    <div v-else-if="isApplying" class="d-flex align-items-center text-secondary">
       <gl-loading-icon class="d-flex-center mr-2" />
-      <span>{{ __('Applying suggestion') }}</span>
+      <span>{{ applyingSuggestionsMessage }}</span>
+    </div>
+    <div v-else-if="canApply && isBatched" class="d-flex align-items-center">
+      <gl-deprecated-button
+        class="btn-inverted js-remove-from-batch-btn btn-grouped"
+        :disabled="isApplying"
+        @click="removeSuggestionFromBatch"
+      >
+        {{ __('Remove from batch') }}
+      </gl-deprecated-button>
+      <gl-deprecated-button
+        v-gl-tooltip.viewport="__('This also resolves all related threads')"
+        class="btn-inverted js-apply-batch-btn btn-grouped"
+        :disabled="isApplying"
+        variant="success"
+        @click="applySuggestionBatch"
+      >
+        {{ __('Apply suggestions') }}
+        <span class="badge badge-pill badge-pill-success">
+          {{ batchSuggestionsCount }}
+        </span>
+      </gl-deprecated-button>
     </div>
+    <div v-else-if="canApply" class="d-flex align-items-center">
+      <gl-deprecated-button
+        class="btn-inverted js-add-to-batch-btn btn-grouped"
+        :disabled="isApplying"
+        @click="addSuggestionToBatch"
+      >
+        {{ __('Add suggestion to batch') }}
+      </gl-deprecated-button>
       <gl-deprecated-button
-      v-else-if="canApply"
-      v-gl-tooltip.viewport="__('This also resolves the discussion')"
-      class="btn-inverted js-apply-btn"
+        v-gl-tooltip.viewport="__('This also resolves the thread')"
+        class="btn-inverted js-apply-btn btn-grouped"
         :disabled="isApplying"
         variant="success"
         @click="applySuggestion"
@@ -63,4 +128,5 @@ export default {
         {{ __('Apply suggestion') }}
       </gl-deprecated-button>
     </div>
+  </div>
 </template>

app/assets/javascripts/vue_shared/components/markdown/suggestions.vue

@@ -16,6 +16,11 @@ export default {
       required: false,
       default: () => [],
     },
+    batchSuggestionsInfo: {
+      type: Array,
+      required: false,
+      default: () => [],
+    },
     noteHtml: {
       type: String,
       required: true,
@@ -68,18 +73,30 @@ export default {
       this.isRendered = true;
     },
     generateDiff(suggestionIndex) {
-      const { suggestions, disabled, helpPagePath } = this;
+      const { suggestions, disabled, batchSuggestionsInfo, helpPagePath } = this;
       const suggestion =
         suggestions && suggestions[suggestionIndex] ? suggestions[suggestionIndex] : {};
       const SuggestionDiffComponent = Vue.extend(SuggestionDiff);
       const suggestionDiff = new SuggestionDiffComponent({
-        propsData: { disabled, suggestion, helpPagePath },
+        propsData: { disabled, suggestion, batchSuggestionsInfo, helpPagePath },
       });
 
       suggestionDiff.$on('apply', ({ suggestionId, callback }) => {
         this.$emit('apply', { suggestionId, callback, flashContainer: this.$el });
       });
 
+      suggestionDiff.$on('applyBatch', () => {
+        this.$emit('applyBatch', { flashContainer: this.$el });
+      });
+
+      suggestionDiff.$on('addToBatch', suggestionId => {
+        this.$emit('addToBatch', suggestionId);
+      });
+
+      suggestionDiff.$on('removeFromBatch', suggestionId => {
+        this.$emit('removeFromBatch', suggestionId);
+      });
+
       return suggestionDiff;
     },
     reset() {

app/assets/stylesheets/framework/badges.scss

@@ -3,4 +3,12 @@
   background-color: $badge-bg;
   color: $gray-800;
   vertical-align: baseline;
+
+  // Do not use this!
+  // This is a temporary workaround until the new GlBadge component
+  // is available: https://gitlab.com/gitlab-org/gitlab-ui/-/issues/481
+  &.badge-pill-success {
+    background-color: rgba($green-500, 0.2);
+    color: $green;
+  }
 }

app/services/suggestions/apply_service.rb

@@ -2,109 +2,49 @@
 
 module Suggestions
   class ApplyService < ::BaseService
-    DEFAULT_SUGGESTION_COMMIT_MESSAGE = 'Apply suggestion to %{file_path}'
-
-    PLACEHOLDERS = {
-      'project_path' => ->(suggestion, user) { suggestion.project.path },
-      'project_name' => ->(suggestion, user) { suggestion.project.name },
-      'file_path' => ->(suggestion, user) { suggestion.file_path },
-      'branch_name' => ->(suggestion, user) { suggestion.branch },
-      'username' => ->(suggestion, user) { user.username },
-      'user_full_name' => ->(suggestion, user) { user.name }
-    }.freeze
-
-    # This regex is built dynamically using the keys from the PLACEHOLDER struct.
-    # So, we can easily add new placeholder just by modifying the PLACEHOLDER hash.
-    # This regex will build the new PLACEHOLDER_REGEX with the new information
-    PLACEHOLDERS_REGEX = Regexp.union(PLACEHOLDERS.keys.map { |key| Regexp.new(Regexp.escape(key)) }).freeze
-
-    attr_reader :current_user
-
-    def initialize(current_user)
+    def initialize(current_user, *suggestions)
       @current_user = current_user
+      @suggestion_set = Gitlab::Suggestions::SuggestionSet.new(suggestions)
     end
 
-    def execute(suggestion)
-      unless suggestion.appliable?(cached: false)
-        return error('Suggestion is not appliable')
+    def execute
+      if suggestion_set.valid?
+        result
+      else
+        error(suggestion_set.error_message)
       end
-
-      unless latest_source_head?(suggestion)
-        return error('The file has been changed')
     end
 
-      diff_file = suggestion.diff_file
-
-      unless diff_file
-        return error('The file was not found')
-      end
+    private
 
-      params = file_update_params(suggestion, diff_file)
-      result = ::Files::UpdateService.new(suggestion.project, current_user, params).execute
+    attr_reader :current_user, :suggestion_set
 
-      if result[:status] == :success
-        suggestion.update(commit_id: result[:result], applied: true)
+    def result
+      multi_service.execute.tap do |result|
+        update_suggestions(result)
       end
-
-      result
-    rescue Files::UpdateService::FileChangedError
-      error('The file has been changed')
     end
 
-    private
+    def update_suggestions(result)
+      return unless result[:status] == :success
 
-    # Checks whether the latest source branch HEAD matches with
-    # the position HEAD we're using to update the file content. Since
-    # the persisted HEAD is updated async (for MergeRequest),
-    # it's more consistent to fetch this data directly from the
-    # repository.
-    def latest_source_head?(suggestion)
-      suggestion.position.head_sha == suggestion.noteable.source_branch_sha
+      Suggestion.id_in(suggestion_set.suggestions)
+        .update_all(commit_id: result[:result], applied: true)
     end
 
-    def file_update_params(suggestion, diff_file)
-      blob = diff_file.new_blob
-      project = suggestion.project
-      file_path = suggestion.file_path
-      branch_name = suggestion.branch
-      file_content = new_file_content(suggestion, blob)
-      commit_message = processed_suggestion_commit_message(suggestion)
-
-      file_last_commit =
-        Gitlab::Git::Commit.last_for_path(project.repository,
-                                          blob.commit_id,
-                                          blob.path)
-
-      {
-        file_path: file_path,
-        branch_name: branch_name,
-        start_branch: branch_name,
+    def multi_service
+      params = {
         commit_message: commit_message,
-        file_content: file_content,
-        last_commit_sha: file_last_commit&.id
+        branch_name: suggestion_set.branch,
+        start_branch: suggestion_set.branch,
+        actions: suggestion_set.actions
       }
-    end
-
-    def new_file_content(suggestion, blob)
-      range = suggestion.from_line_index..suggestion.to_line_index
 
-      blob.load_all_data!
-      content = blob.data.lines
-      content[range] = suggestion.to_content
-
-      content.join
-    end
-
-    def suggestion_commit_message(project)
-      project.suggestion_commit_message.presence || DEFAULT_SUGGESTION_COMMIT_MESSAGE
+      ::Files::MultiService.new(suggestion_set.project, current_user, params)
     end
 
-    def processed_suggestion_commit_message(suggestion)
-      message = suggestion_commit_message(suggestion.project)
-
-      Gitlab::StringPlaceholderReplacer.replace_string_placeholders(message, PLACEHOLDERS_REGEX) do |key|
-        PLACEHOLDERS[key].call(suggestion, current_user)
-      end
+    def commit_message
+      Gitlab::Suggestions::CommitMessage.new(current_user, suggestion_set).message
     end
   end
 end

app/views/projects/_merge_request_merge_suggestions_settings.html.haml

@@ -9,9 +9,9 @@
       anchor: 'configure-the-commit-message-for-applied-suggestions'),
       target: '_blank'
   .mb-2
-    = form.text_field :suggestion_commit_message, class: 'form-control mb-2', placeholder: Suggestions::ApplyService::DEFAULT_SUGGESTION_COMMIT_MESSAGE
+    = form.text_field :suggestion_commit_message, class: 'form-control mb-2', placeholder: Gitlab::Suggestions::CommitMessage::DEFAULT_SUGGESTION_COMMIT_MESSAGE
     %p.form-text.text-muted
       = s_('ProjectSettings|The variables GitLab supports:')
-      - Suggestions::ApplyService::PLACEHOLDERS.keys.each do |placeholder|
+      - Gitlab::Suggestions::CommitMessage::PLACEHOLDERS.keys.each do |placeholder|
         %code
           = "%{#{placeholder}}".html_safe

changelogs/unreleased/25486-batch-suggestions.yml

+---
+title: User can apply multiple suggestions at the same time.
+merge_request: 22439
+author: Jesse Hall
+type: added

doc/user/discussions/index.md

@@ -459,32 +459,60 @@ instead of the usual three.
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/13086) in GitLab 12.7.
 
-GitLab uses `Apply suggestion to %{file_path}` by default as commit messages
-when applying Suggestions. This commit message can be customized to
-follow any guidelines you might have. To do so, expand the **Merge requests**
+GitLab uses a default commit message
+when applying Suggestions: `Apply %{suggestions_count} suggestion(s) to %{files_count} file(s)`
+
+For example, consider that a user applied 3 suggestions to 2 different files, the default commit message will be: **Apply 3 suggestion(s) to 2 file(s)**
+
+These commit messages can be customized to follow any guidelines you might have. To do so, expand the **Merge requests**
 tab within your project's **General** settings and change the
 **Merge suggestions** text:
 
-![Custom commit message for applied Suggestions](img/suggestions_custom_commit_messages_v12_7.png)
+![Custom commit message for applied Suggestions](img/suggestions_custom_commit_messages_v13_1.jpg)
 
 You can also use following variables besides static text:
 
 | Variable | Description | Output example |
 |---|---|---|
+| `%{branch_name}` | The name of the branch the Suggestion(s) was(were) applied to. | `my-feature-branch` |
+| `%{files_count}` | The number of file(s) to which Suggestion(s) was(were) applied.| **2** |
+| `%{file_paths}` | The path(s) of the file(s) Suggestion(s) was(were) applied to. Paths are separated by commas.| `docs/index.md, docs/about.md` |
 | `%{project_path}` | The project path. | `my-group/my-project` |
 | `%{project_name}` | The human-readable name of the project. | **My Project** |
-| `%{file_path}` | The path of the file the Suggestion is applied to. | `docs/index.md` |
-| `%{branch_name}` | The name of the branch the Suggestion is applied on. | `my-feature-branch` |
-| `%{username}` | The username of the user applying the Suggestion. | `user_1` |
-| `%{user_full_name}` | The full name of the user applying the Suggestion. | **User 1** |
+| `%{suggestions_count}` | The number of Suggestions applied.| **3** |
+| `%{username}` | The username of the user applying Suggestion(s). | `user_1` |
+| `%{user_full_name}` | The full name of the user applying Suggestion(s). | **User 1** |
 
 For example, to customize the commit message to output
 **Addresses user_1's review**, set the custom text to
 `Addresses %{username}'s review`.
 
 NOTE: **Note:**
-Custom commit messages for each applied Suggestion will be
-introduced by [#25381](https://gitlab.com/gitlab-org/gitlab/-/issues/25381).
+Custom commit messages for each applied Suggestion (and for batch Suggestions) will be
+introduced by [#25381](https://gitlab.com/gitlab-org/gitlab/issues/25381).
+
+### Batch Suggestions
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/25486) in GitLab 13.1.
+
+You can apply multiple suggestions at once to reduce the number of commits added
+to your branch to address your reviewers' requests.
+
+1. To start a batch of suggestions that will be applied with a single commit, click **Add suggestion to batch**:
+
+   ![A code change suggestion displayed, with the button to add the suggestion to a batch highlighted.](img/add_first_suggestion_to_batch_v13_1.jpg "Add a suggestion to a batch")
+
+1. Add as many additional suggestions to the batch as you wish:
+
+   ![A code change suggestion displayed, with the button to add an additional suggestion to a batch highlighted.](img/add_another_suggestion_to_batch_v13_1.jpg "Add another suggestion to a batch")
+
+1. To remove suggestions, click **Remove from batch**:
+
+   ![A code change suggestion displayed, with the button to remove that suggestion from its batch highlighted.](img/remove_suggestion_from_batch_v13_1.jpg "Remove a suggestion from a batch")
+
+1. Having added all the suggestions to your liking, when ready, click **Apply suggestions**:
+
+   ![A code change suggestion displayed, with the button to apply the batch of suggestions highlighted.](img/apply_batch_of_suggestions_v13_1.jpg "Apply a batch of suggestions")
 
 ## Start a thread by replying to a standard comment
 

lib/api/suggestions.rb

@@ -14,18 +14,51 @@ module API
       put ':id/apply' do
         suggestion = Suggestion.find_by_id(params[:id])
 
-        not_found! unless suggestion
-        authorize! :apply_suggestion, suggestion
+        if suggestion
+          apply_suggestions(suggestion, current_user)
+        else
+          render_api_error!(_('Suggestion is not applicable as the suggestion was not found.'), :not_found)
+        end
+      end
+
+      desc 'Apply multiple suggestion patches in the Merge Request where they were created' do
+        success Entities::Suggestion
+      end
+      params do
+        requires :ids, type: Array[String], desc: "An array of suggestion ID's"
+      end
+      put 'batch_apply' do
+        ids = params[:ids]
+
+        suggestions = Suggestion.id_in(ids)
 
-        result = ::Suggestions::ApplyService.new(current_user).execute(suggestion)
+        if suggestions.size == ids.length
+          apply_suggestions(suggestions, current_user)
+        else
+          render_api_error!(_('Suggestions are not applicable as one or more suggestions were not found.'), :not_found)
+        end
+      end
+    end
+
+    helpers do
+      def apply_suggestions(suggestions, current_user)
+        authorize_suggestions(*suggestions)
+
+        result = ::Suggestions::ApplyService.new(current_user, *suggestions).execute
 
         if result[:status] == :success
-          present suggestion, with: Entities::Suggestion, current_user: current_user
+          present suggestions, with: Entities::Suggestion, current_user: current_user
         else
-          http_status = result[:http_status] || 400
+          http_status = result[:http_status] || :bad_request
           render_api_error!(result[:message], http_status)
         end
       end
+
+      def authorize_suggestions(*suggestions)
+        suggestions.each do |suggestion|
+          authorize! :apply_suggestion, suggestion
+        end
+      end
     end
   end
 end

lib/gitlab/suggestions/commit_message.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Suggestions
+    class CommitMessage
+      DEFAULT_SUGGESTION_COMMIT_MESSAGE =
+        'Apply %{suggestions_count} suggestion(s) to %{files_count} file(s)'
+
+      def initialize(user, suggestion_set)
+        @user = user
+        @suggestion_set = suggestion_set
+      end
+
+      def message
+        project = suggestion_set.project
+        user_defined_message = project.suggestion_commit_message.presence
+        message = user_defined_message || DEFAULT_SUGGESTION_COMMIT_MESSAGE
+
+        Gitlab::StringPlaceholderReplacer
+          .replace_string_placeholders(message, PLACEHOLDERS_REGEX) do |key|
+          PLACEHOLDERS[key].call(user, suggestion_set)
+        end
+      end
+
+      def self.format_paths(paths)
+        paths.sort.join(', ')
+      end
+
+      private_class_method :format_paths
+
+      private
+
+      attr_reader :user, :suggestion_set
+
+      PLACEHOLDERS = {
+        'branch_name' => ->(user, suggestion_set) { suggestion_set.branch },
+        'files_count' => ->(user, suggestion_set) { suggestion_set.file_paths.length },
+        'file_paths' => ->(user, suggestion_set) { format_paths(suggestion_set.file_paths) },
+        'project_name' => ->(user, suggestion_set) { suggestion_set.project.name },
+        'project_path' => ->(user, suggestion_set) { suggestion_set.project.path },
+        'user_full_name' => ->(user, suggestion_set) { user.name },
+        'username' => ->(user, suggestion_set) { user.username },
+        'suggestions_count' => ->(user, suggestion_set) { suggestion_set.suggestions.size }
+      }.freeze
+
+      # This regex is built dynamically using the keys from the PLACEHOLDER struct.
+      # So, we can easily add new placeholder just by modifying the PLACEHOLDER hash.
+      # This regex will build the new PLACEHOLDER_REGEX with the new information
+      PLACEHOLDERS_REGEX = Regexp.union(PLACEHOLDERS.keys.map do |key|
+        Regexp.new(Regexp.escape(key))
+      end).freeze
+    end
+  end
+end

lib/gitlab/suggestions/file_suggestion.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Suggestions
+    class FileSuggestion
+      include Gitlab::Utils::StrongMemoize
+
+      SuggestionForDifferentFileError = Class.new(StandardError)
+
+      def initialize
+        @suggestions = []
+      end
+
+      def add_suggestion(new_suggestion)
+        if for_different_file?(new_suggestion)
+          raise SuggestionForDifferentFileError,
+                'Only add suggestions for the same file.'
+        end
+
+        suggestions << new_suggestion
+      end
+
+      def line_conflict?
+        strong_memoize(:line_conflict) do
+          _line_conflict?
+        end
+      end
+
+      def new_content
+        @new_content ||= _new_content
+      end
+
+      def file_path
+        @file_path ||= _file_path
+      end
+
+      private
+
+      attr_accessor :suggestions
+
+      def blob
+        first_suggestion&.diff_file&.new_blob
+      end
+
+      def blob_data_lines
+        blob.load_all_data!
+        blob.data.lines
+      end
+
+      def current_content
+        @current_content ||= blob.nil? ? [''] : blob_data_lines
+      end
+
+      def _new_content
+        current_content.tap do |content|
+          suggestions.each do |suggestion|
+            range = line_range(suggestion)
+            content[range] = suggestion.to_content
+          end
+        end.join
+      end
+
+      def line_range(suggestion)
+        suggestion.from_line_index..suggestion.to_line_index
+      end
+
+      def for_different_file?(suggestion)
+        file_path && file_path != suggestion_file_path(suggestion)
+      end
+
+      def suggestion_file_path(suggestion)
+        suggestion&.diff_file&.file_path
+      end
+
+      def first_suggestion
+        suggestions.first
+      end
+
+      def _file_path
+        suggestion_file_path(first_suggestion)
+      end
+
+      def _line_conflict?
+        has_conflict = false
+
+        suggestions.each_with_object([]) do |suggestion, ranges|
+          range_in_test = line_range(suggestion)
+
+          if has_range_conflict?(range_in_test, ranges)
+            has_conflict = true
+            break
+          end
+
+          ranges << range_in_test
+        end
+
+        has_conflict
+      end
+
+      def has_range_conflict?(range_in_test, ranges)
+        ranges.any? do |range|
+          range.overlaps?(range_in_test)
+        end
+      end
+    end
+  end
+end

lib/gitlab/suggestions/suggestion_set.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Suggestions
+    class SuggestionSet
+      attr_reader :suggestions
+
+      def initialize(suggestions)
+        @suggestions = suggestions
+      end
+
+      def project
+        first_suggestion.project
+      end
+
+      def branch
+        first_suggestion.branch
+      end
+
+      def valid?
+        error_message.nil?
+      end
+
+      def error_message
+        @error_message ||= _error_message
+      end
+
+      def actions
+        @actions ||= suggestions_per_file.map do |file_path, file_suggestion|
+          {
+            action: 'update',
+            file_path: file_path,
+            content: file_suggestion.new_content
+          }
+        end
+      end
+
+      def file_paths
+        @file_paths ||= suggestions.map(&:file_path).uniq
+      end
+
+      private
+
+      def first_suggestion
+        suggestions.first
+      end
+
+      def suggestions_per_file
+        @suggestions_per_file ||= _suggestions_per_file
+      end
+
+      def _suggestions_per_file
+        suggestions.each_with_object({}) do |suggestion, result|
+          file_path = suggestion.diff_file.file_path
+          file_suggestion = result[file_path] ||= FileSuggestion.new
+          file_suggestion.add_suggestion(suggestion)
+        end
+      end
+
+      def file_suggestions
+        suggestions_per_file.values
+      end
+
+      def first_file_suggestion
+        file_suggestions.first
+      end
+
+      def _error_message
+        suggestions.each do |suggestion|
+          message = error_for_suggestion(suggestion)
+
+          return message if message
+        end
+
+        has_line_conflict = file_suggestions.any? do |file_suggestion|
+          file_suggestion.line_conflict?
+        end
+
+        if has_line_conflict
+          return _('Suggestions are not applicable as their lines cannot overlap.')
+        end
+
+        nil
+      end
+
+      def error_for_suggestion(suggestion)
+        unless suggestion.diff_file
+          return _('A file was not found.')
+        end
+
+        unless on_same_branch?(suggestion)
+          return _('Suggestions must all be on the same branch.')
+        end
+
+        unless suggestion.appliable?(cached: false)
+          return _('A suggestion is not applicable.')
+        end
+
+        unless latest_source_head?(suggestion)
+          return _('A file has been changed.')
+        end
+
+        nil
+      end
+
+      def on_same_branch?(suggestion)
+        branch == suggestion.branch
+      end
+
+      # Checks whether the latest source branch HEAD matches with
+      # the position HEAD we're using to update the file content. Since
+      # the persisted HEAD is updated async (for MergeRequest),
+      # it's more consistent to fetch this data directly from the
+      # repository.
+      def latest_source_head?(suggestion)
+        suggestion.position.head_sha == suggestion.noteable.source_branch_sha
+      end
+    end
+  end
+end

locale/gitlab.pot

@@ -941,6 +941,12 @@ msgstr ""
 msgid "A deleted user"
 msgstr ""
 
+msgid "A file has been changed."
+msgstr ""
+
+msgid "A file was not found."
+msgstr ""
+
 msgid "A file with '%{file_name}' already exists in %{branch} branch"
 msgstr ""
 
@@ -1007,6 +1013,9 @@ msgstr ""
 msgid "A subscription will trigger a new pipeline on the default branch of this project when a pipeline successfully completes for a new tag on the %{default_branch_docs} of the subscribed project."
 msgstr ""
 
+msgid "A suggestion is not applicable."
+msgstr ""
+
 msgid "A terraform report was generated in your pipelines."
 msgstr ""
 
@@ -1366,6 +1375,9 @@ msgstr ""
 msgid "Add strikethrough text"
 msgstr ""
 
+msgid "Add suggestion to batch"
+msgstr ""
+
 msgid "Add system hook"
 msgstr ""
 
@@ -2568,6 +2580,9 @@ msgstr ""
 msgid "Apply suggestion"
 msgstr ""
 
+msgid "Apply suggestions"
+msgstr ""
+
 msgid "Apply template"
 msgstr ""
 
@@ -2586,7 +2601,10 @@ msgstr ""
 msgid "Applying multiple commands"
 msgstr ""
 
-msgid "Applying suggestion"
+msgid "Applying suggestion..."
+msgstr ""
+
+msgid "Applying suggestions..."
 msgstr ""
 
 msgid "Approval rules"
@@ -18265,6 +18283,9 @@ msgstr ""
 msgid "Remove fork relationship"
 msgstr ""
 
+msgid "Remove from batch"
+msgstr ""
+
 msgid "Remove from board"
 msgstr ""
 
@@ -20502,6 +20523,9 @@ msgstr ""
 msgid "Something went wrong while adding your award. Please try again."
 msgstr ""
 
+msgid "Something went wrong while applying the batch of suggestions. Please try again."
+msgstr ""
+
 msgid "Something went wrong while applying the suggestion. Please try again."
 msgstr ""
 
@@ -21459,6 +21483,18 @@ msgstr ""
 msgid "SuggestedColors|Very pale orange"
 msgstr ""
 
+msgid "Suggestion is not applicable as the suggestion was not found."
+msgstr ""
+
+msgid "Suggestions are not applicable as one or more suggestions were not found."
+msgstr ""
+
+msgid "Suggestions are not applicable as their lines cannot overlap."
+msgstr ""
+
+msgid "Suggestions must all be on the same branch."
+msgstr ""
+
 msgid "Suggestions:"
 msgstr ""
 
@@ -22428,7 +22464,10 @@ msgstr ""
 msgid "This action can lead to data loss. To prevent accidental actions we ask you to confirm your intention."
 msgstr ""
 
-msgid "This also resolves the discussion"
+msgid "This also resolves all related threads"
+msgstr ""
+
+msgid "This also resolves the thread"
 msgstr ""
 
 msgid "This application was created by %{link_to_owner}."

spec/features/merge_request/user_suggests_changes_on_diff_spec.rb

@@ -93,6 +93,100 @@ describe 'User comments on a diff', :js do
     end
   end
 
+  context 'applying suggestions in batches' do
+    def hash(path)
+      diff_file = merge_request.diffs(paths: [path]).diff_files.first
+      Digest::SHA1.hexdigest(diff_file.file_path)
+    end
+
+    file1 = 'files/ruby/popen.rb'
+    file2 = 'files/ruby/regex.rb'
+
+    let(:files) do
+      [
+        {
+          hash: hash(file1),
+          line_code: "#{hash(file1)}_12_12"
+        },
+        {
+          hash: hash(file2),
+          line_code: "#{hash(file2)}_21_21"
+        }
+      ]
+    end
+
+    it 'can add and remove suggestions from a batch' do
+      files.each_with_index do |file, index|
+        page.within("[id='#{file[:hash]}']") do
+          find("button[title='Show full file']").click
+          wait_for_requests
+
+          click_diff_line(find("[id='#{file[:line_code]}']"))
+
+          page.within('.js-discussion-note-form') do
+            fill_in('note_note', with: "```suggestion\n# change to a comment\n```")
+            click_button('Add comment now')
+            wait_for_requests
+          end
+        end
+
+        page.within("[id='#{file[:hash]}']") do
+          expect(page).not_to have_content('Applied')
+
+          click_button('Add suggestion to batch')
+          wait_for_requests
+
+          expect(page).to have_content('Remove from batch')
+          expect(page).to have_content("Apply suggestions #{index + 1}")
+        end
+      end
+
+      page.within("[id='#{files[0][:hash]}']") do
+        click_button('Remove from batch')
+        wait_for_requests
+
+        expect(page).to have_content('Apply suggestion')
+        expect(page).to have_content('Add suggestion to batch')
+      end
+
+      page.within("[id='#{files[1][:hash]}']") do
+        expect(page).to have_content('Remove from batch')
+        expect(page).to have_content('Apply suggestions 1')
+      end
+    end
+
+    it 'can apply multiple suggestions as a batch' do
+      files.each_with_index do |file, index|
+        page.within("[id='#{file[:hash]}']") do
+          find("button[title='Show full file']").click
+          wait_for_requests
+
+          click_diff_line(find("[id='#{file[:line_code]}']"))
+
+          page.within('.js-discussion-note-form') do
+            fill_in('note_note', with: "```suggestion\n# change to a comment\n```")
+            click_button('Add comment now')
+            wait_for_requests
+          end
+        end
+
+        page.within("[id='#{file[:hash]}']") do
+          click_button('Add suggestion to batch')
+          wait_for_requests
+        end
+      end
+
+      expect(page).not_to have_content('Applied')
+
+      page.within("[id='#{files[0][:hash]}']") do
+        click_button('Apply suggestions 2')
+        wait_for_requests
+      end
+
+      expect(page).to have_content('Applied').twice
+    end
+  end
+
   context 'multiple suggestions in expanded lines' do
     # https://gitlab.com/gitlab-org/gitlab/issues/38277
     it 'suggestions are appliable', :quarantine do

spec/frontend/notes/mock_data.js

@@ -1254,3 +1254,16 @@ export const discussionFiltersMock = [
     value: 2,
   },
 ];
+
+export const batchSuggestionsInfoMock = [
+  {
+    suggestionId: 'a123',
+    noteId: 'b456',
+    discussionId: 'c789',
+  },
+  {
+    suggestionId: 'a001',
+    noteId: 'b002',
+    discussionId: 'c003',
+  },
+];

spec/frontend/notes/stores/actions_spec.js

@@ -15,6 +15,7 @@ import {
   userDataMock,
   noteableDataMock,
   individualNote,
+  batchSuggestionsInfoMock,
 } from '../mock_data';
 import axios from '~/lib/utils/axios_utils';
 
@@ -890,7 +891,23 @@ describe('Actions Notes Store', () => {
       testSubmitSuggestion(done, () => {
         expect(commit).not.toHaveBeenCalled();
         expect(dispatch).not.toHaveBeenCalled();
-        expect(Flash).toHaveBeenCalledWith(`${TEST_ERROR_MESSAGE}.`, 'alert', flashContainer);
+        expect(Flash).toHaveBeenCalledWith(TEST_ERROR_MESSAGE, 'alert', flashContainer);
+      });
+    });
+
+    it('when service fails, and no error message available, uses default message', done => {
+      const response = { response: 'foo' };
+
+      Api.applySuggestion.mockReturnValue(Promise.reject(response));
+
+      testSubmitSuggestion(done, () => {
+        expect(commit).not.toHaveBeenCalled();
+        expect(dispatch).not.toHaveBeenCalled();
+        expect(Flash).toHaveBeenCalledWith(
+          'Something went wrong while applying the suggestion. Please try again.',
+          'alert',
+          flashContainer,
+        );
       });
     });
 
@@ -903,6 +920,130 @@ describe('Actions Notes Store', () => {
     });
   });
 
+  describe('submitSuggestionBatch', () => {
+    const discussionIds = batchSuggestionsInfoMock.map(({ discussionId }) => discussionId);
+    const batchSuggestionsInfo = batchSuggestionsInfoMock;
+
+    let flashContainer;
+
+    beforeEach(() => {
+      jest.spyOn(Api, 'applySuggestionBatch');
+      dispatch.mockReturnValue(Promise.resolve());
+      Api.applySuggestionBatch.mockReturnValue(Promise.resolve());
+      state = { batchSuggestionsInfo };
+      flashContainer = {};
+    });
+
+    const testSubmitSuggestionBatch = (done, expectFn) => {
+      actions
+        .submitSuggestionBatch({ commit, dispatch, state }, { flashContainer })
+        .then(expectFn)
+        .then(done)
+        .catch(done.fail);
+    };
+
+    it('when service succeeds, commits, resolves discussions, resets batch and applying batch state', done => {
+      testSubmitSuggestionBatch(done, () => {
+        expect(commit.mock.calls).toEqual([
+          [mutationTypes.SET_APPLYING_BATCH_STATE, true],
+          [mutationTypes.APPLY_SUGGESTION, batchSuggestionsInfo[0]],
+          [mutationTypes.APPLY_SUGGESTION, batchSuggestionsInfo[1]],
+          [mutationTypes.CLEAR_SUGGESTION_BATCH],
+          [mutationTypes.SET_APPLYING_BATCH_STATE, false],
+        ]);
+
+        expect(dispatch.mock.calls).toEqual([
+          ['resolveDiscussion', { discussionId: discussionIds[0] }],
+          ['resolveDiscussion', { discussionId: discussionIds[1] }],
+        ]);
+
+        expect(Flash).not.toHaveBeenCalled();
+      });
+    });
+
+    it('when service fails, flashes error message, resets applying batch state', done => {
+      const response = { response: { data: { message: TEST_ERROR_MESSAGE } } };
+
+      Api.applySuggestionBatch.mockReturnValue(Promise.reject(response));
+
+      testSubmitSuggestionBatch(done, () => {
+        expect(commit.mock.calls).toEqual([
+          [mutationTypes.SET_APPLYING_BATCH_STATE, true],
+          [mutationTypes.SET_APPLYING_BATCH_STATE, false],
+        ]);
+
+        expect(dispatch).not.toHaveBeenCalled();
+        expect(Flash).toHaveBeenCalledWith(TEST_ERROR_MESSAGE, 'alert', flashContainer);
+      });
+    });
+
+    it('when service fails, and no error message available, uses default message', done => {
+      const response = { response: 'foo' };
+
+      Api.applySuggestionBatch.mockReturnValue(Promise.reject(response));
+
+      testSubmitSuggestionBatch(done, () => {
+        expect(commit.mock.calls).toEqual([
+          [mutationTypes.SET_APPLYING_BATCH_STATE, true],
+          [mutationTypes.SET_APPLYING_BATCH_STATE, false],
+        ]);
+
+        expect(dispatch).not.toHaveBeenCalled();
+        expect(Flash).toHaveBeenCalledWith(
+          'Something went wrong while applying the batch of suggestions. Please try again.',
+          'alert',
+          flashContainer,
+        );
+      });
+    });
+
+    it('when resolve discussions fails, fails gracefully, resets batch and applying batch state', done => {
+      dispatch.mockReturnValue(Promise.reject());
+
+      testSubmitSuggestionBatch(done, () => {
+        expect(commit.mock.calls).toEqual([
+          [mutationTypes.SET_APPLYING_BATCH_STATE, true],
+          [mutationTypes.APPLY_SUGGESTION, batchSuggestionsInfo[0]],
+          [mutationTypes.APPLY_SUGGESTION, batchSuggestionsInfo[1]],
+          [mutationTypes.CLEAR_SUGGESTION_BATCH],
+          [mutationTypes.SET_APPLYING_BATCH_STATE, false],
+        ]);
+
+        expect(Flash).not.toHaveBeenCalled();
+      });
+    });
+  });
+
+  describe('addSuggestionInfoToBatch', () => {
+    const suggestionInfo = batchSuggestionsInfoMock[0];
+
+    it("adds a suggestion's info to the current batch", done => {
+      testAction(
+        actions.addSuggestionInfoToBatch,
+        suggestionInfo,
+        { batchSuggestionsInfo: [] },
+        [{ type: 'ADD_SUGGESTION_TO_BATCH', payload: suggestionInfo }],
+        [],
+        done,
+      );
+    });
+  });
+
+  describe('removeSuggestionInfoFromBatch', () => {
+    const suggestionInfo = batchSuggestionsInfoMock[0];
+
+    it("removes a suggestion's info the current batch", done => {
+      testAction(
+        actions.removeSuggestionInfoFromBatch,
+        suggestionInfo.suggestionId,
+        { batchSuggestionsInfo: [suggestionInfo] },
+        [{ type: 'REMOVE_SUGGESTION_FROM_BATCH', payload: suggestionInfo.suggestionId }],
+        [],
+        done,
+      );
+    });
+  });
+
   describe('filterDiscussion', () => {
     const path = 'some-discussion-path';
     const filter = 0;

spec/frontend/notes/stores/mutation_spec.js

@@ -9,6 +9,7 @@ import {
   noteableDataMock,
   individualNote,
   notesWithDescriptionChanges,
+  batchSuggestionsInfoMock,
 } from '../mock_data';
 
 const RESOLVED_NOTE = { resolvable: true, resolved: true };
@@ -700,4 +701,108 @@ describe('Notes Store mutations', () => {
       expect(state.isToggleBlockedIssueWarning).toEqual(false);
     });
   });
+
+  describe('SET_APPLYING_BATCH_STATE', () => {
+    const buildDiscussions = suggestionsInfo => {
+      const suggestions = suggestionsInfo.map(({ suggestionId }) => ({ id: suggestionId }));
+
+      const notes = suggestionsInfo.map(({ noteId }, index) => ({
+        id: noteId,
+        suggestions: [suggestions[index]],
+      }));
+
+      return suggestionsInfo.map(({ discussionId }, index) => ({
+        id: discussionId,
+        notes: [notes[index]],
+      }));
+    };
+
+    let state;
+    let batchedSuggestionInfo;
+    let discussions;
+    let suggestions;
+
+    beforeEach(() => {
+      [batchedSuggestionInfo] = batchSuggestionsInfoMock;
+      suggestions = batchSuggestionsInfoMock.map(({ suggestionId }) => ({ id: suggestionId }));
+      discussions = buildDiscussions(batchSuggestionsInfoMock);
+      state = {
+        batchSuggestionsInfo: [batchedSuggestionInfo],
+        discussions,
+      };
+    });
+
+    it('sets is_applying_batch to a boolean value for all batched suggestions', () => {
+      mutations.SET_APPLYING_BATCH_STATE(state, true);
+
+      const updatedSuggestion = {
+        ...suggestions[0],
+        is_applying_batch: true,
+      };
+
+      const expectedSuggestions = [updatedSuggestion, suggestions[1]];
+
+      const actualSuggestions = state.discussions
+        .map(discussion => discussion.notes.map(n => n.suggestions))
+        .flat(2);
+
+      expect(actualSuggestions).toEqual(expectedSuggestions);
+    });
+  });
+
+  describe('ADD_SUGGESTION_TO_BATCH', () => {
+    let state;
+
+    beforeEach(() => {
+      state = { batchSuggestionsInfo: [] };
+    });
+
+    it("adds a suggestion's info to a batch", () => {
+      const suggestionInfo = {
+        suggestionId: 'a123',
+        noteId: 'b456',
+        discussionId: 'c789',
+      };
+
+      mutations.ADD_SUGGESTION_TO_BATCH(state, suggestionInfo);
+
+      expect(state.batchSuggestionsInfo).toEqual([suggestionInfo]);
+    });
+  });
+
+  describe('REMOVE_SUGGESTION_FROM_BATCH', () => {
+    let state;
+    let suggestionInfo1;
+    let suggestionInfo2;
+
+    beforeEach(() => {
+      [suggestionInfo1, suggestionInfo2] = batchSuggestionsInfoMock;
+
+      state = {
+        batchSuggestionsInfo: [suggestionInfo1, suggestionInfo2],
+      };
+    });
+
+    it("removes a suggestion's info from a batch", () => {
+      mutations.REMOVE_SUGGESTION_FROM_BATCH(state, suggestionInfo1.suggestionId);
+
+      expect(state.batchSuggestionsInfo).toEqual([suggestionInfo2]);
+    });
+  });
+
+  describe('CLEAR_SUGGESTION_BATCH', () => {
+    let state;
+
+    beforeEach(() => {
+      state = {
+        batchSuggestionsInfo: batchSuggestionsInfoMock,
+      };
+    });
+
+    it('removes info for all suggestions from a batch', () => {
+      mutations.CLEAR_SUGGESTION_BATCH(state);
+
+      expect(state.batchSuggestionsInfo.length).toEqual(0);
+    });
+  });
 });

spec/frontend/vue_shared/components/markdown/__snapshots__/suggestion_diff_spec.js.snap

@@ -5,8 +5,11 @@ exports[`Suggestion Diff component matches snapshot 1`] = `
   class="md-suggestion"
 >
   <suggestion-diff-header-stub
+    batchsuggestionscount="1"
     class="qa-suggestion-diff-header js-suggestion-diff-header"
     helppagepath="path_to_docs"
+    isapplyingbatch="true"
+    isbatched="true"
   />
    
   <table

spec/frontend/vue_shared/components/markdown/suggestion_diff_header_spec.js

@@ -3,8 +3,11 @@ import { shallowMount } from '@vue/test-utils';
 import SuggestionDiffHeader from '~/vue_shared/components/markdown/suggestion_diff_header.vue';
 
 const DEFAULT_PROPS = {
+  batchSuggestionsCount: 2,
   canApply: true,
   isApplied: false,
+  isBatched: false,
+  isApplyingBatch: false,
   helpPagePath: 'path_to_docs',
 };
 
@@ -25,6 +28,9 @@ describe('Suggestion Diff component', () => {
   });
 
   const findApplyButton = () => wrapper.find('.js-apply-btn');
+  const findApplyBatchButton = () => wrapper.find('.js-apply-batch-btn');
+  const findAddToBatchButton = () => wrapper.find('.js-add-to-batch-btn');
+  const findRemoveFromBatchButton = () => wrapper.find('.js-remove-from-batch-btn');
   const findHeader = () => wrapper.find('.js-suggestion-diff-header');
   const findHelpButton = () => wrapper.find('.js-help-btn');
   const findLoading = () => wrapper.find(GlLoadingIcon);
@@ -44,19 +50,24 @@ describe('Suggestion Diff component', () => {
     expect(findHelpButton().exists()).toBe(true);
   });
 
-  it('renders an apply button', () => {
+  it('renders apply suggestion and add to batch buttons', () => {
     createComponent();
 
     const applyBtn = findApplyButton();
+    const addToBatchBtn = findAddToBatchButton();
 
     expect(applyBtn.exists()).toBe(true);
     expect(applyBtn.html().includes('Apply suggestion')).toBe(true);
+
+    expect(addToBatchBtn.exists()).toBe(true);
+    expect(addToBatchBtn.html().includes('Add suggestion to batch')).toBe(true);
   });
 
-  it('does not render an apply button if `canApply` is set to false', () => {
+  it('does not render apply suggestion and add to batch buttons if `canApply` is set to false', () => {
     createComponent({ canApply: false });
 
     expect(findApplyButton().exists()).toBe(false);
+    expect(findAddToBatchButton().exists()).toBe(false);
   });
 
   describe('when apply suggestion is clicked', () => {
@@ -73,13 +84,14 @@ describe('Suggestion Diff component', () => {
       });
     });
 
-    it('hides apply button', () => {
+    it('hides  apply suggestion and add to batch buttons', () => {
       expect(findApplyButton().exists()).toBe(false);
+      expect(findAddToBatchButton().exists()).toBe(false);
     });
 
     it('shows loading', () => {
       expect(findLoading().exists()).toBe(true);
-      expect(wrapper.text()).toContain('Applying suggestion');
+      expect(wrapper.text()).toContain('Applying suggestion...');
     });
 
     it('when callback of apply is called, hides loading', () => {
@@ -93,4 +105,104 @@ describe('Suggestion Diff component', () => {
       });
     });
   });
+
+  describe('when add to batch is clicked', () => {
+    it('emits addToBatch', () => {
+      createComponent();
+
+      findAddToBatchButton().vm.$emit('click');
+
+      expect(wrapper.emittedByOrder()).toContainEqual({
+        name: 'addToBatch',
+        args: [],
+      });
+    });
+  });
+
+  describe('when remove from batch is clicked', () => {
+    it('emits removeFromBatch', () => {
+      createComponent({ isBatched: true });
+
+      findRemoveFromBatchButton().vm.$emit('click');
+
+      expect(wrapper.emittedByOrder()).toContainEqual({
+        name: 'removeFromBatch',
+        args: [],
+      });
+    });
+  });
+
+  describe('apply suggestions is clicked', () => {
+    it('emits applyBatch', () => {
+      createComponent({ isBatched: true });
+
+      findApplyBatchButton().vm.$emit('click');
+
+      expect(wrapper.emittedByOrder()).toContainEqual({
+        name: 'applyBatch',
+        args: [],
+      });
+    });
+  });
+
+  describe('when isBatched is true', () => {
+    it('shows remove from batch and apply batch buttons and displays the batch count', () => {
+      createComponent({
+        batchSuggestionsCount: 9,
+        isBatched: true,
+      });
+
+      const applyBatchBtn = findApplyBatchButton();
+      const removeFromBatchBtn = findRemoveFromBatchButton();
+
+      expect(removeFromBatchBtn.exists()).toBe(true);
+      expect(removeFromBatchBtn.html().includes('Remove from batch')).toBe(true);
+
+      expect(applyBatchBtn.exists()).toBe(true);
+      expect(applyBatchBtn.html().includes('Apply suggestions')).toBe(true);
+      expect(applyBatchBtn.html().includes(String('9'))).toBe(true);
+    });
+
+    it('hides add to batch and apply buttons', () => {
+      createComponent({
+        isBatched: true,
+      });
+
+      expect(findApplyButton().exists()).toBe(false);
+      expect(findAddToBatchButton().exists()).toBe(false);
+    });
+
+    describe('when isBatched and isApplyingBatch are true', () => {
+      it('shows loading', () => {
+        createComponent({
+          isBatched: true,
+          isApplyingBatch: true,
+        });
+
+        expect(findLoading().exists()).toBe(true);
+        expect(wrapper.text()).toContain('Applying suggestions...');
+      });
+
+      it('adjusts message for batch with single suggestion', () => {
+        createComponent({
+          batchSuggestionsCount: 1,
+          isBatched: true,
+          isApplyingBatch: true,
+        });
+
+        expect(findLoading().exists()).toBe(true);
+        expect(wrapper.text()).toContain('Applying suggestion...');
+      });
+
+      it('hides remove from batch and apply suggestions buttons', () => {
+        createComponent({
+          isBatched: true,
+          isApplyingBatch: true,
+        });
+
+        expect(findRemoveFromBatchButton().exists()).toBe(false);
+        expect(findApplyBatchButton().exists()).toBe(false);
+      });
+    });
+  });
 });

spec/frontend/vue_shared/components/markdown/suggestion_diff_spec.js

@@ -3,9 +3,10 @@ import SuggestionDiffComponent from '~/vue_shared/components/markdown/suggestion
 import SuggestionDiffHeader from '~/vue_shared/components/markdown/suggestion_diff_header.vue';
 import SuggestionDiffRow from '~/vue_shared/components/markdown/suggestion_diff_row.vue';
 
+const suggestionId = 1;
 const MOCK_DATA = {
   suggestion: {
-    id: 1,
+    id: suggestionId,
     diff_lines: [
       {
         can_receive_suggestion: false,
@@ -38,8 +39,10 @@ const MOCK_DATA = {
         type: 'new',
       },
     ],
+    is_applying_batch: true,
   },
   helpPagePath: 'path_to_docs',
+  batchSuggestionsInfo: [{ suggestionId }],
 };
 
 describe('Suggestion Diff component', () => {
@@ -70,17 +73,24 @@ describe('Suggestion Diff component', () => {
     expect(wrapper.findAll(SuggestionDiffRow)).toHaveLength(3);
   });
 
-  it('emits apply event on sugestion diff header apply', () => {
-    wrapper.find(SuggestionDiffHeader).vm.$emit('apply', 'test-event');
+  it.each`
+    event                | childArgs         | args
+    ${'apply'}           | ${['test-event']} | ${[{ callback: 'test-event', suggestionId }]}
+    ${'applyBatch'}      | ${[]}             | ${[]}
+    ${'addToBatch'}      | ${[]}             | ${[suggestionId]}
+    ${'removeFromBatch'} | ${[]}             | ${[suggestionId]}
+  `('emits $event event on sugestion diff header $event', ({ event, childArgs, args }) => {
+    wrapper.find(SuggestionDiffHeader).vm.$emit(event, ...childArgs);
 
-    expect(wrapper.emitted('apply')).toBeDefined();
-    expect(wrapper.emitted('apply')).toEqual([
-      [
-        {
-          callback: 'test-event',
-          suggestionId: 1,
-        },
-      ],
-    ]);
+    expect(wrapper.emitted(event)).toBeDefined();
+    expect(wrapper.emitted(event)).toEqual([args]);
+  });
+
+  it('passes suggestion batch props to suggestion diff header', () => {
+    expect(wrapper.find(SuggestionDiffHeader).props()).toMatchObject({
+      batchSuggestionsCount: 1,
+      isBatched: true,
+      isApplyingBatch: MOCK_DATA.suggestion.is_applying_batch,
+    });
   });
 });

spec/lib/gitlab/suggestions/commit_message_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Suggestions::CommitMessage do
+  def create_suggestion(file_path, new_line, to_content)
+    position = Gitlab::Diff::Position.new(old_path: file_path,
+                                          new_path: file_path,
+                                          old_line: nil,
+                                          new_line: new_line,
+                                          diff_refs: merge_request.diff_refs)
+
+    diff_note = create(:diff_note_on_merge_request,
+                       noteable: merge_request,
+                       position: position,
+                       project: project)
+
+    create(:suggestion,
+           :content_from_repo,
+           note: diff_note,
+           to_content: to_content)
+  end
+
+  let_it_be(:user) do
+    create(:user, :commit_email, name: 'Test User', username: 'test.user')
+  end
+
+  let_it_be(:project) do
+    create(:project, :repository, path: 'project-1', name: 'Project_1')
+  end
+
+  let_it_be(:merge_request) do
+    create(:merge_request, source_project: project, target_project: project)
+  end
+
+  let_it_be(:suggestion_set) do
+    suggestion1 = create_suggestion('files/ruby/popen.rb', 9, '*** SUGGESTION 1 ***')
+    suggestion2 = create_suggestion('files/ruby/popen.rb', 13, '*** SUGGESTION 2 ***')
+    suggestion3 = create_suggestion('files/ruby/regex.rb', 22, '*** SUGGESTION 3 ***')
+
+    Gitlab::Suggestions::SuggestionSet.new([suggestion1, suggestion2, suggestion3])
+  end
+
+  describe '#message' do
+    before do
+      # Updating the suggestion_commit_message on a project shared across specs
+      # avoids recreating the repository for each spec.
+      project.update!(suggestion_commit_message: message)
+    end
+
+    context 'when a custom commit message is not specified' do
+      let(:expected_message) { 'Apply 3 suggestion(s) to 2 file(s)' }
+
+      context 'and is nil' do
+        let(:message) { nil }
+
+        it 'uses the default commit message' do
+          expect(described_class
+                   .new(user, suggestion_set)
+                   .message).to eq(expected_message)
+        end
+      end
+
+      context 'and is an empty string' do
+        let(:message) { '' }
+
+        it 'uses the default commit message' do
+          expect(described_class
+                   .new(user, suggestion_set)
+                   .message).to eq(expected_message)
+        end
+      end
+    end
+
+    context 'is specified and includes all placeholders' do
+      let(:message) do
+        '*** %{branch_name} %{files_count} %{file_paths} %{project_name} %{project_path} %{user_full_name} %{username} %{suggestions_count} ***'
+      end
+
+      it 'generates a custom commit message' do
+        expect(Gitlab::Suggestions::CommitMessage
+                 .new(user, suggestion_set)
+                 .message).to eq('*** master 2 files/ruby/popen.rb, files/ruby/regex.rb Project_1 project-1 Test User test.user 3 ***')
+      end
+    end
+  end
+end

spec/lib/gitlab/suggestions/file_suggestion_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Suggestions::FileSuggestion do
+  def create_suggestion(new_line, to_content)
+    position = Gitlab::Diff::Position.new(old_path: file_path,
+                                          new_path: file_path,
+                                          old_line: nil,
+                                          new_line: new_line,
+                                          diff_refs: merge_request.diff_refs)
+
+    diff_note = create(:diff_note_on_merge_request,
+                       noteable: merge_request,
+                       position: position,
+                       project: project)
+
+    create(:suggestion,
+           :content_from_repo,
+           note: diff_note,
+           to_content: to_content)
+  end
+
+  let_it_be(:user) { create(:user) }
+
+  let_it_be(:file_path) { 'files/ruby/popen.rb'}
+
+  let_it_be(:project) { create(:project, :repository) }
+
+  let_it_be(:merge_request) do
+    create(:merge_request, source_project: project, target_project: project)
+  end
+
+  let_it_be(:suggestion1) do
+    create_suggestion(9, "      *** SUGGESTION 1 ***\n")
+  end
+
+  let_it_be(:suggestion2) do
+    create_suggestion(15, "      *** SUGGESTION 2 ***\n")
+  end
+
+  let(:file_suggestion) { described_class.new }
+
+  describe '#add_suggestion' do
+    it 'succeeds when adding a suggestion for the same file as the original' do
+      file_suggestion.add_suggestion(suggestion1)
+
+      expect { file_suggestion.add_suggestion(suggestion2) }.not_to raise_error
+    end
+
+    it 'raises an error when adding a suggestion for a different file' do
+      allow(suggestion2)
+        .to(receive_message_chain(:diff_file, :file_path)
+        .and_return('path/to/different/file'))
+
+      file_suggestion.add_suggestion(suggestion1)
+
+      expect { file_suggestion.add_suggestion(suggestion2) }.to(
+        raise_error(described_class::SuggestionForDifferentFileError)
+      )
+    end
+  end
+
+  describe '#line_conflict' do
+    def stub_suggestions(line_index_spans)
+      fake_suggestions = line_index_spans.map do |span|
+        double("Suggestion",
+               from_line_index: span[:from_line_index],
+               to_line_index: span[:to_line_index])
+      end
+
+      allow(file_suggestion).to(receive(:suggestions).and_return(fake_suggestions))
+    end
+
+    context 'when line ranges do not overlap' do
+      it 'return false' do
+        stub_suggestions(
+          [
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            },
+            {
+              from_line_index: 11,
+              to_line_index: 20
+            }
+          ]
+        )
+
+        expect(file_suggestion.line_conflict?).to be(false)
+      end
+    end
+
+    context 'when line ranges are identical' do
+      it 'returns true' do
+        stub_suggestions(
+          [
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            },
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            }
+          ]
+        )
+
+        expect(file_suggestion.line_conflict?).to be(true)
+      end
+    end
+
+    context 'when one range starts, and the other ends, on the same line' do
+      it 'returns true' do
+        stub_suggestions(
+          [
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            },
+            {
+              from_line_index: 10,
+              to_line_index: 20
+            }
+          ]
+        )
+
+        expect(file_suggestion.line_conflict?).to be(true)
+      end
+    end
+
+    context 'when one line range contains the other' do
+      it 'returns true' do
+        stub_suggestions(
+          [
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            },
+            {
+              from_line_index: 5,
+              to_line_index: 7
+            }
+          ]
+        )
+
+        expect(file_suggestion.line_conflict?).to be(true)
+      end
+    end
+
+    context 'when line ranges overlap' do
+      it 'returns true' do
+        stub_suggestions(
+          [
+            {
+              from_line_index: 0,
+              to_line_index: 10
+            },
+            {
+              from_line_index: 8,
+              to_line_index: 15
+            }
+          ]
+        )
+
+        expect(file_suggestion.line_conflict?).to be(true)
+      end
+    end
+
+    context 'when no suggestions have been added' do
+      it 'returns false' do
+        expect(file_suggestion.line_conflict?).to be(false)
+      end
+    end
+  end
+
+  describe '#new_content' do
+    it 'returns a blob with the suggestions applied to it' do
+      file_suggestion.add_suggestion(suggestion1)
+      file_suggestion.add_suggestion(suggestion2)
+
+      expected_content = <<-CONTENT.strip_heredoc
+        require 'fileutils'
+        require 'open3'
+
+        module Popen
+          extend self
+
+          def popen(cmd, path=nil)
+            unless cmd.is_a?(Array)
+              *** SUGGESTION 1 ***
+            end
+
+            path ||= Dir.pwd
+
+            vars = {
+              *** SUGGESTION 2 ***
+            }
+
+            options = {
+              chdir: path
+            }
+
+            unless File.directory?(path)
+              FileUtils.mkdir_p(path)
+            end
+
+            @cmd_output = ""
+            @cmd_status = 0
+
+            Open3.popen3(vars, *cmd, options) do |stdin, stdout, stderr, wait_thr|
+              @cmd_output << stdout.read
+              @cmd_output << stderr.read
+              @cmd_status = wait_thr.value.exitstatus
+            end
+
+            return @cmd_output, @cmd_status
+          end
+        end
+      CONTENT
+
+      expect(file_suggestion.new_content).to eq(expected_content)
+    end
+
+    it 'returns an empty string when no suggestions have been added' do
+      expect(file_suggestion.new_content).to eq('')
+    end
+  end
+
+  describe '#file_path' do
+    it 'returns the path of the file associated with the suggestions' do
+      file_suggestion.add_suggestion(suggestion1)
+
+      expect(file_suggestion.file_path).to eq(file_path)
+    end
+
+    it 'returns nil if no suggestions have been added' do
+      expect(file_suggestion.file_path).to be(nil)
+    end
+  end
+end

spec/lib/gitlab/suggestions/suggestion_set_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Suggestions::SuggestionSet do
+  def create_suggestion(file_path, new_line, to_content)
+    position = Gitlab::Diff::Position.new(old_path: file_path,
+                                          new_path: file_path,
+                                          old_line: nil,
+                                          new_line: new_line,
+                                          diff_refs: merge_request.diff_refs)
+
+    diff_note = create(:diff_note_on_merge_request,
+                       noteable: merge_request,
+                       position: position,
+                       project: project)
+
+    create(:suggestion,
+           :content_from_repo,
+           note: diff_note,
+           to_content: to_content)
+  end
+
+  let_it_be(:user) { create(:user) }
+
+  let_it_be(:project) { create(:project, :repository) }
+
+  let_it_be(:merge_request) do
+    create(:merge_request, source_project: project, target_project: project)
+  end
+
+  let_it_be(:suggestion) { create(:suggestion)}
+
+  let_it_be(:suggestion2) do
+    create_suggestion('files/ruby/popen.rb', 13, "*** SUGGESTION 2 ***")
+  end
+
+  let_it_be(:suggestion3) do
+    create_suggestion('files/ruby/regex.rb', 22, "*** SUGGESTION 3 ***")
+  end
+
+  let_it_be(:unappliable_suggestion) { create(:suggestion, :unappliable) }
+
+  let(:suggestion_set) { described_class.new([suggestion]) }
+
+  describe '#project' do
+    it 'returns the project associated with the suggestions' do
+      expected_project = suggestion.project
+
+      expect(suggestion_set.project).to be(expected_project)
+    end
+  end
+
+  describe '#branch' do
+    it 'returns the branch associated with the suggestions' do
+      expected_branch = suggestion.branch
+
+      expect(suggestion_set.branch).to be(expected_branch)
+    end
+  end
+
+  describe '#valid?' do
+    it 'returns true if no errors are found' do
+      expect(suggestion_set.valid?).to be(true)
+    end
+
+    it 'returns false if an error is found' do
+      suggestion_set = described_class.new([unappliable_suggestion])
+
+      expect(suggestion_set.valid?).to be(false)
+    end
+  end
+
+  describe '#error_message' do
+    it 'returns an error message if an error is found' do
+      suggestion_set = described_class.new([unappliable_suggestion])
+
+      expect(suggestion_set.error_message).to be_a(String)
+    end
+
+    it 'returns nil if no errors are found' do
+      expect(suggestion_set.error_message).to be(nil)
+    end
+  end
+
+  describe '#actions' do
+    it 'returns an array of hashes with proper key/value pairs' do
+      first_action = suggestion_set.actions.first
+
+      file_path, file_suggestion = suggestion_set
+                                     .send(:suggestions_per_file).first
+
+      expect(first_action[:action]).to be('update')
+      expect(first_action[:file_path]).to eq(file_path)
+      expect(first_action[:content]).to eq(file_suggestion.new_content)
+    end
+  end
+
+  describe '#file_paths' do
+    it 'returns an array of unique file paths associated with the suggestions' do
+      suggestion_set = described_class.new([suggestion, suggestion2, suggestion3])
+
+      expected_paths = %w(files/ruby/popen.rb files/ruby/regex.rb)
+
+      actual_paths = suggestion_set.file_paths
+
+      expect(actual_paths.sort).to eq(expected_paths)
+    end
+  end
+end

spec/requests/api/suggestions_spec.rb

@@ -7,8 +7,7 @@ describe API::Suggestions do
   let(:user) { create(:user) }
 
   let(:merge_request) do
-    create(:merge_request, source_project: project,
-                           target_project: project)
+    create(:merge_request, source_project: project, target_project: project)
   end
 
   let(:position) do
@@ -19,26 +18,45 @@ describe API::Suggestions do
                                diff_refs: merge_request.diff_refs)
   end
 
+  let(:position2) do
+    Gitlab::Diff::Position.new(old_path: "files/ruby/popen.rb",
+                               new_path: "files/ruby/popen.rb",
+                               old_line: nil,
+                               new_line: 15,
+                               diff_refs: merge_request.diff_refs)
+  end
+
   let(:diff_note) do
-    create(:diff_note_on_merge_request, noteable: merge_request,
+    create(:diff_note_on_merge_request,
+           noteable: merge_request,
            position: position,
            project: project)
   end
 
-  describe "PUT /suggestions/:id/apply" do
-    let(:url) { "/suggestions/#{suggestion.id}/apply" }
+  let(:diff_note2) do
+    create(:diff_note_on_merge_request, noteable: merge_request,
+           position: position2,
+           project: project)
+  end
 
-    context 'when successfully applies patch' do
   let(:suggestion) do
     create(:suggestion, note: diff_note,
            from_content: "      raise RuntimeError, \"System commands must be given as an array of strings\"\n",
            to_content: "      raise RuntimeError, 'Explosion'\n      # explosion?")
   end
 
-      it 'returns 200 with json content' do
+  let(:unappliable_suggestion) do
+    create(:suggestion, :unappliable, note: diff_note2)
+  end
+
+  describe "PUT /suggestions/:id/apply" do
+    let(:url) { "/suggestions/#{suggestion.id}/apply" }
+
+    context 'when successfully applies patch' do
+      it 'renders an ok response and returns json content' do
         project.add_maintainer(user)
 
-        put api(url, user), params: { id: suggestion.id }
+        put api(url, user)
 
         expect(response).to have_gitlab_http_status(:ok)
         expect(json_response)
@@ -48,31 +66,105 @@ describe API::Suggestions do
     end
 
     context 'when not able to apply patch' do
-      let(:suggestion) do
-        create(:suggestion, :unappliable, note: diff_note)
-      end
+      let(:url) { "/suggestions/#{unappliable_suggestion.id}/apply" }
 
-      it 'returns 400 with json content' do
+      it 'renders a bad request error and returns json content' do
         project.add_maintainer(user)
 
-        put api(url, user), params: { id: suggestion.id }
+        put api(url, user)
 
         expect(response).to have_gitlab_http_status(:bad_request)
-        expect(json_response).to eq({ 'message' => 'Suggestion is not appliable' })
+        expect(json_response).to eq({ 'message' => 'A suggestion is not applicable.' })
+      end
+    end
+
+    context 'when suggestion is not found' do
+      let(:url) { "/suggestions/foo-123/apply" }
+
+      it 'renders a not found error and returns json content' do
+        project.add_maintainer(user)
+
+        put api(url, user)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response).to eq({ 'message' => 'Suggestion is not applicable as the suggestion was not found.' })
       end
     end
 
     context 'when unauthorized' do
-      let(:suggestion) do
-        create(:suggestion, note: diff_note,
-                            from_content: "      raise RuntimeError, \"System commands must be given as an array of strings\"\n",
-                            to_content: "      raise RuntimeError, 'Explosion'\n      # explosion?")
+      it 'renders a forbidden error and returns json content' do
+        project.add_reporter(user)
+
+        put api(url, user)
+
+        expect(response).to have_gitlab_http_status(:forbidden)
+        expect(json_response).to eq({ 'message' => '403 Forbidden' })
+      end
+    end
+  end
+
+  describe "PUT /suggestions/batch_apply" do
+    let(:suggestion2) do
+      create(:suggestion, note: diff_note2,
+             from_content: "      \"PWD\" => path\n",
+             to_content: "      *** FOO ***\n")
+    end
+
+    let(:url) { "/suggestions/batch_apply" }
+
+    context 'when successfully applies multiple patches as a batch' do
+      it 'renders an ok response and returns json content' do
+        project.add_maintainer(user)
+
+        put api(url, user), params: { ids: [suggestion.id, suggestion2.id] }
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(json_response).to all(include('id', 'from_line', 'to_line',
+                                             'appliable', 'applied',
+                                             'from_content', 'to_content'))
+      end
     end
 
-      it 'returns 403 with json content' do
+    context 'when not able to apply one or more of the patches' do
+      it 'renders a bad request error and returns json content' do
+        project.add_maintainer(user)
+
+        put api(url, user),
+            params: { ids: [suggestion.id, unappliable_suggestion.id] }
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+        expect(json_response).to eq({ 'message' => 'A suggestion is not applicable.' })
+      end
+    end
+
+    context 'with missing suggestions' do
+      it 'renders a not found error and returns json content if any suggestion is not found' do
+        project.add_maintainer(user)
+
+        put api(url, user), params: { ids: [suggestion.id, 'foo-123'] }
+
+        expect(response).to have_gitlab_http_status(:not_found)
+        expect(json_response)
+          .to eq({ 'message' => 'Suggestions are not applicable as one or more suggestions were not found.' })
+      end
+
+      it 'renders a bad request error and returns json content when no suggestions are provided' do
+        project.add_maintainer(user)
+
+        put api(url, user), params: {}
+
+        expect(response).to have_gitlab_http_status(:bad_request)
+        expect(json_response)
+          .to eq({ 'error' => "ids is missing" })
+      end
+    end
+
+    context 'when unauthorized' do
+      it 'renders a forbidden error and returns json content' do
         project.add_reporter(user)
 
-        put api(url, user), params: { id: suggestion.id }
+        put api(url, user),
+            params: { ids: [suggestion.id, suggestion2.id] }
 
         expect(response).to have_gitlab_http_status(:forbidden)
         expect(json_response).to eq({ 'message' => '403 Forbidden' })

spec/views/projects/edit.html.haml_spec.rb

@@ -32,26 +32,28 @@ describe 'projects/edit' do
     it 'displays all possible variables' do
       render
 
-      expect(rendered).to have_content('%{project_path}')
-      expect(rendered).to have_content('%{project_name}')
-      expect(rendered).to have_content('%{file_path}')
       expect(rendered).to have_content('%{branch_name}')
-      expect(rendered).to have_content('%{username}')
+      expect(rendered).to have_content('%{files_count}')
+      expect(rendered).to have_content('%{file_paths}')
+      expect(rendered).to have_content('%{project_name}')
+      expect(rendered).to have_content('%{project_path}')
       expect(rendered).to have_content('%{user_full_name}')
+      expect(rendered).to have_content('%{username}')
+      expect(rendered).to have_content('%{suggestions_count}')
     end
 
     it 'displays a placeholder if none is set' do
       render
 
-      expect(rendered).to have_field('project[suggestion_commit_message]', placeholder: 'Apply suggestion to %{file_path}')
+      expect(rendered).to have_field('project[suggestion_commit_message]', placeholder: "Apply %{suggestions_count} suggestion(s) to %{files_count} file(s)")
     end
 
     it 'displays the user entered value' do
-      project.update!(suggestion_commit_message: 'refactor: changed %{file_path}')
+      project.update!(suggestion_commit_message: 'refactor: changed %{file_paths}')
 
       render
 
-      expect(rendered).to have_field('project[suggestion_commit_message]', with: 'refactor: changed %{file_path}')
+      expect(rendered).to have_field('project[suggestion_commit_message]', with: 'refactor: changed %{file_paths}')
     end
   end