Fix showing outdated discussions on Changes tab

# Conflicts:
#	app/assets/javascripts/diffs/components/inline_diff_comment_row.vue
#	spec/javascripts/diffs/store/getters_spec.js

app/assets/javascripts/diffs/components/diff_line_gutter_content.vue

@@ -77,7 +77,8 @@ export default {
       diffViewType: state => state.diffs.diffViewType,
       diffFiles: state => state.diffs.diffFiles,
     }),
-    ...mapGetters(['isLoggedIn', 'discussionsByLineCode']),
+    ...mapGetters(['isLoggedIn']),
+    ...mapGetters('diffs', ['discussionsByLineCode']),
     lineHref() {
       return this.lineCode ? `#${this.lineCode}` : '#';
     },

app/assets/javascripts/diffs/components/inline_diff_comment_row.vue

@@ -30,13 +30,16 @@ export default {
     ...mapState({
       diffLineCommentForms: state => state.diffs.diffLineCommentForms,
     }),
-    ...mapGetters(['discussionsByLineCode']),
+    ...mapGetters('diffs', ['discussionsByLineCode']),
     discussions() {
       return this.discussionsByLineCode[this.line.lineCode] || [];
     },
     className() {
       return this.discussions.length ? '' : 'js-temp-notes-holder';
     },
+    hasCommentForm() {
+      return this.diffLineCommentForms[this.line.lineCode];
+    },
   },
 };
 </script>
@@ -57,7 +60,7 @@ export default {
           :discussions="discussions"
         />
         <diff-line-note-form
-          v-if="diffLineCommentForms[line.lineCode]"
+          v-if="hasCommentForm"
           :diff-file="diffFile"
           :diff-lines="diffLines"
           :line="line"

app/assets/javascripts/diffs/components/inline_diff_view.vue

@@ -20,8 +20,7 @@ export default {
     },
   },
   computed: {
-    ...mapGetters('diffs', ['commitId']),
-    ...mapGetters(['discussionsByLineCode']),
+    ...mapGetters('diffs', ['commitId', 'discussionsByLineCode']),
     ...mapState({
       diffLineCommentForms: state => state.diffs.diffLineCommentForms,
     }),

app/assets/javascripts/diffs/components/parallel_diff_comment_row.vue

@@ -30,7 +30,7 @@ export default {
     ...mapState({
       diffLineCommentForms: state => state.diffs.diffLineCommentForms,
     }),
-    ...mapGetters(['discussionsByLineCode']),
+    ...mapGetters('diffs', ['discussionsByLineCode']),
     leftLineCode() {
       return this.line.left.lineCode;
     },

app/assets/javascripts/diffs/components/parallel_diff_view.vue

@@ -21,8 +21,7 @@ export default {
     },
   },
   computed: {
-    ...mapGetters('diffs', ['commitId']),
-    ...mapGetters(['discussionsByLineCode']),
+    ...mapGetters('diffs', ['commitId', 'discussionsByLineCode']),
     ...mapState({
       diffLineCommentForms: state => state.diffs.diffLineCommentForms,
     }),

app/assets/javascripts/diffs/store/getters.js

 import _ from 'underscore';
+import { convertObjectPropsToCamelCase } from '~/lib/utils/common_utils';
 import { PARALLEL_DIFF_VIEW_TYPE, INLINE_DIFF_VIEW_TYPE } from '../constants';
+import { getDiffRefsByLineCode } from './utils';
 
 export const isParallelView = state => state.diffViewType === PARALLEL_DIFF_VIEW_TYPE;
 
@@ -56,5 +58,43 @@ export const getDiffFileDiscussions = (state, getters, rootState, rootGetters) =
       discussion.diff_discussion && _.isEqual(discussion.diff_file.file_hash, diff.fileHash),
   ) || [];
 
+/**
+ * Returns an Object with discussions by their diff line code
+ * To avoid rendering outdated discussions on the Changes tab we should do a bunch of SHA
+ * comparisions. `note.position.formatter` have the current version diff refs but
+ * `note.original_position.formatter` will have the first version's diff refs.
+ * If line diff refs matches with one of them, we should render it as a discussion on Changes tab.
+ *
+ * @param {Object} diff
+ * @returns {Array}
+ */
+export const discussionsByLineCode = (state, getters, rootState, rootGetters) => {
+  const diffRefsByLineCode = getDiffRefsByLineCode(state.diffFiles);
+
+  return rootGetters.discussions.reduce((acc, note) => {
+    const isDiffDiscussion = note.diff_discussion;
+    const hasLineCode = note.line_code;
+    const isResolvable = note.resolvable;
+    const diffRefs = diffRefsByLineCode[note.line_code];
+
+    if (isDiffDiscussion && hasLineCode && isResolvable && diffRefs) {
+      const refs = convertObjectPropsToCamelCase(note.position.formatter);
+      const originalRefs = convertObjectPropsToCamelCase(note.original_position.formatter);
+
+      if (_.isEqual(refs, diffRefs) || _.isEqual(originalRefs, diffRefs)) {
+        const lineCode = note.line_code;
+
+        if (acc[lineCode]) {
+          acc[lineCode].push(note);
+        } else {
+          acc[lineCode] = [note];
+        }
+      }
+    }
+
+    return acc;
+  }, {});
+};
+
 // prevent babel-plugin-rewire from generating an invalid default during karma∂ tests
 export default () => {};

app/assets/javascripts/diffs/store/utils.js

@@ -173,3 +173,24 @@ export function trimFirstCharOfLineContent(line = {}) {
 
   return parsedLine;
 }
+
+export function getDiffRefsByLineCode(diffFiles) {
+  return diffFiles.reduce((acc, diffFile) => {
+    const { baseSha, headSha, startSha } = diffFile.diffRefs;
+    const { newPath, oldPath } = diffFile;
+
+    // We can only use highlightedDiffLines to create the map of diff lines because
+    // highlightedDiffLines will also include every parallel diff line in it.
+    if (diffFile.highlightedDiffLines) {
+      diffFile.highlightedDiffLines.forEach(line => {
+        const { lineCode, oldLine, newLine } = line;
+
+        if (lineCode) {
+          acc[lineCode] = { baseSha, headSha, startSha, newPath, oldPath, oldLine, newLine };
+        }
+      });
+    }
+
+    return acc;
+  }, {});
+}

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

@@ -28,18 +28,6 @@ export const notesById = state =>
     return acc;
   }, {});
 
-export const discussionsByLineCode = state =>
-  state.discussions.reduce((acc, note) => {
-    if (note.diff_discussion && note.line_code && note.resolvable) {
-      // For context about line notes: there might be multiple notes with the same line code
-      const items = acc[note.line_code] || [];
-      items.push(note);
-
-      Object.assign(acc, { [note.line_code]: items });
-    }
-    return acc;
-  }, {});
-
 export const noteableType = state => {
   const { ISSUE_NOTEABLE_TYPE, MERGE_REQUEST_NOTEABLE_TYPE, EPIC_NOTEABLE_TYPE } = constants;
 

app/serializers/discussion_entity.rb

@@ -4,6 +4,7 @@ class DiscussionEntity < Grape::Entity
 
   expose :id, :reply_id
   expose :position, if: -> (d, _) { d.diff_discussion? && !d.legacy_diff_discussion? }
+  expose :original_position, if: -> (d, _) { d.diff_discussion? && !d.legacy_diff_discussion? }
   expose :line_code, if: -> (d, _) { d.diff_discussion? }
   expose :expanded?, as: :expanded
   expose :active?, as: :active, if: -> (d, _) { d.diff_discussion? }

changelogs/unreleased/_acet-fix-outdated-discussions.yml

+---
+title: Fix showing outdated discussions on Changes tab
+merge_request: 20445
+author:
+type: fixed

spec/javascripts/diffs/components/diff_line_gutter_content_spec.js

@@ -18,10 +18,12 @@ describe('DiffLineGutterContent', () => {
   };
   const setDiscussions = component => {
     component.$store.dispatch('setInitialNotes', getDiscussionsMockData());
+    component.$store.commit('diffs/SET_DIFF_DATA', { diffFiles: [getDiffFileMock()] });
   };
 
   const resetDiscussions = component => {
     component.$store.dispatch('setInitialNotes', []);
+    component.$store.commit('diffs/SET_DIFF_DATA', {});
   };
 
   describe('computed', () => {

spec/javascripts/diffs/components/inline_diff_view_spec.js

@@ -33,6 +33,7 @@ describe('InlineDiffView', () => {
     it('should render discussions', done => {
       const el = component.$el;
       component.$store.dispatch('setInitialNotes', getDiscussionsMockData());
+      component.$store.commit('diffs/SET_DIFF_DATA', { diffFiles: [getDiffFileMock()] });
 
       Vue.nextTick(() => {
         expect(el.querySelectorAll('.notes_holder').length).toEqual(1);

spec/javascripts/diffs/mock_data/diff_discussions.js

@@ -12,6 +12,17 @@ export default {
       head_sha: 'c48ee0d1bf3b30453f5b32250ce03134beaa6d13',
     },
   },
+  original_position: {
+    formatter: {
+      old_line: null,
+      new_line: 2,
+      old_path: 'CHANGELOG',
+      new_path: 'CHANGELOG',
+      base_sha: 'e63f41fe459e62e1228fcef60d7189127aeba95a',
+      start_sha: 'd9eaefe5a676b820c57ff18cf5b68316025f7962',
+      head_sha: 'c48ee0d1bf3b30453f5b32250ce03134beaa6d13',
+    },
+  },
   line_code: '1c497fbb3a46b78edf04cc2a2fa33f67e3ffbe2a_1_2',
   expanded: true,
   notes: [

spec/javascripts/diffs/store/getters_spec.js

@@ -2,6 +2,7 @@ import * as getters from '~/diffs/store/getters';
 import state from '~/diffs/store/modules/diff_state';
 import { PARALLEL_DIFF_VIEW_TYPE, INLINE_DIFF_VIEW_TYPE } from '~/diffs/constants';
 import discussion from '../mock_data/diff_discussions';
+import diffFile from '../mock_data/diff_file';
 
 describe('Diffs Module Getters', () => {
   let localState;
@@ -184,4 +185,38 @@ describe('Diffs Module Getters', () => {
       ).toEqual(0);
     });
   });
+
+  describe('discussionsByLineCode', () => {
+    let mockState;
+
+    beforeEach(() => {
+      mockState = { diffFiles: [diffFile] };
+    });
+
+    it('should return a map of diff lines with their line codes', () => {
+      const mockGetters = { discussions: [discussionMock] };
+
+      const map = getters.discussionsByLineCode(mockState, {}, {}, mockGetters);
+      expect(map['1c497fbb3a46b78edf04cc2a2fa33f67e3ffbe2a_1_2']).toBeDefined();
+      expect(Object.keys(map).length).toEqual(1);
+    });
+
+    it('should have the diff discussion on the map if the original position matches', () => {
+      discussionMock.position.formatter.base_sha = 'ff9200';
+      const mockGetters = { discussions: [discussionMock] };
+
+      const map = getters.discussionsByLineCode(mockState, {}, {}, mockGetters);
+      expect(map['1c497fbb3a46b78edf04cc2a2fa33f67e3ffbe2a_1_2']).toBeDefined();
+      expect(Object.keys(map).length).toEqual(1);
+    });
+
+    it('should not add an outdated diff discussion to the returned map', () => {
+      discussionMock.position.formatter.base_sha = 'ff9200';
+      discussionMock.original_position.formatter.base_sha = 'ff9200';
+      const mockGetters = { discussions: [discussionMock] };
+
+      const map = getters.discussionsByLineCode(mockState, {}, {}, mockGetters);
+      expect(Object.keys(map).length).toEqual(0);
+    });
+  });
 });

spec/javascripts/diffs/store/utils_spec.js

@@ -207,4 +207,24 @@ describe('DiffsStoreUtils', () => {
       expect(utils.trimFirstCharOfLineContent()).toEqual({});
     });
   });
+
+  describe('getDiffRefsByLineCode', () => {
+    it('should return diffRefs for all highlightedDiffLines', () => {
+      const diffFile = getDiffFileMock();
+      const map = utils.getDiffRefsByLineCode([diffFile]);
+      const { highlightedDiffLines } = diffFile;
+      const lineCodeCount = highlightedDiffLines.reduce(
+        (acc, line) => (line.lineCode ? acc + 1 : acc),
+        0,
+      );
+
+      const { baseSha, headSha, startSha } = diffFile.diffRefs;
+      const targetLine = map[highlightedDiffLines[4].lineCode];
+
+      expect(Object.keys(map).length).toEqual(lineCodeCount);
+      expect(targetLine.baseSha).toEqual(baseSha);
+      expect(targetLine.headSha).toEqual(headSha);
+      expect(targetLine.startSha).toEqual(startSha);
+    });
+  });
 });