Move ide_merge_request_path to routing_helper

- We'll create a follow up for handling the other ide_*
paths in blob

app/helpers/blob_helper.rb

@@ -32,19 +32,6 @@ module BlobHelper
     File.join(segments)
   end
 
-  def ide_merge_request_path(merge_request)
-    target_project = merge_request.target_project
-    source_project = merge_request.source_project
-
-    web_ide_path_base = File.join([ide_path, 'project', source_project.full_path, 'merge_requests', merge_request.iid.to_s])
-
-    if target_project != source_project
-      "#{web_ide_path_base}?#{{ target_project: target_project.full_path }.to_query}"
-    else
-      web_ide_path_base
-    end
-  end
-
   def ide_fork_and_edit_path(project = @project, ref = @ref, path = @path, options = {})
     if current_user
       project_forks_path(project,

app/helpers/gitlab_routing_helper.rb

@@ -343,6 +343,18 @@ module GitlabRoutingHelper
     Gitlab::UrlBuilder.wiki_page_url(wiki, page, only_path: true, **options)
   end
 
+  def gitlab_ide_merge_request_path(merge_request)
+    target_project = merge_request.target_project
+    source_project = merge_request.source_project
+    params = {}
+
+    if target_project != source_project
+      params = { target_project: target_project.full_path }
+    end
+
+    ide_merge_request_path(source_project.namespace, source_project, merge_request, params)
+  end
+
   private
 
   def snippet_query_params(snippet, *args)

app/serializers/diff_file_base_entity.rb

@@ -48,7 +48,7 @@ class DiffFileBaseEntity < Grape::Entity
 
     next unless has_edit_path?(merge_request)
 
-    ide_merge_request_path(merge_request)
+    gitlab_ide_merge_request_path(merge_request)
   end
 
   expose :old_path_html do |diff_file|

config/routes.rb

@@ -122,6 +122,7 @@ Rails.application.routes.draw do
 
     get 'ide' => 'ide#index'
     get 'ide/*vueroute' => 'ide#index', format: false
+    get 'ide/project/:namespace/:project/merge_requests/:id' => 'ide#index', format: false, as: :ide_merge_request
 
     draw :operations
     draw :jira_connect

spec/serializers/diff_file_base_entity_spec.rb

@@ -3,10 +3,24 @@
 require 'spec_helper'
 
 RSpec.describe DiffFileBaseEntity do
-  let(:project) { create(:project, :repository) }
+  include ProjectForksHelper
+
+  let_it_be(:project) { create(:project, :repository) }
+  let_it_be(:user) { create(:user) }
+
   let(:repository) { project.repository }
   let(:entity) { described_class.new(diff_file, options).as_json }
 
+  shared_examples 'nil if removed source branch' do |key|
+    before do
+      allow(merge_request).to receive(:source_branch_exists?).and_return(false)
+    end
+
+    specify do
+      expect(entity[key]).to eq(nil)
+    end
+  end
+
   context 'submodule information for a' do
     let(:commit_sha) { "" }
     let(:commit) { project.commit(commit_sha) }
@@ -67,7 +81,7 @@ RSpec.describe DiffFileBaseEntity do
 
   context 'edit_path' do
     let(:diff_file) { merge_request.diffs.diff_files.to_a.last }
-    let(:options) { { request: EntityRequest.new(current_user: create(:user)), merge_request: merge_request } }
+    let(:options) { { request: EntityRequest.new(current_user: user), merge_request: merge_request } }
     let(:params) { {} }
 
     shared_examples 'a diff file edit path to the source branch' do
@@ -81,16 +95,7 @@ RSpec.describe DiffFileBaseEntity do
       let(:params) { { from_merge_request_iid: merge_request.iid } }
 
       it_behaves_like 'a diff file edit path to the source branch'
-
-      context 'removed source branch' do
-        before do
-          allow(merge_request).to receive(:source_branch_exists?).and_return(false)
-        end
-
-        it do
-          expect(entity[:edit_path]).to eq(nil)
-        end
-      end
+      it_behaves_like 'nil if removed source branch', :edit_path
     end
 
     context 'closed' do
@@ -118,4 +123,30 @@ RSpec.describe DiffFileBaseEntity do
       end
     end
   end
+
+  context 'ide_edit_path' do
+    let(:source_project) { project }
+    let(:merge_request) { create(:merge_request, iid: 123, target_project: target_project, source_project: source_project) }
+    let(:diff_file) { merge_request.diffs.diff_files.to_a.last }
+    let(:options) { { request: EntityRequest.new(current_user: user), merge_request: merge_request } }
+    let(:expected_merge_request_path) { "/-/ide/project/#{source_project.full_path}/merge_requests/#{merge_request.iid}" }
+
+    context 'when source_project and target_project are the same' do
+      let(:target_project) { source_project }
+
+      it_behaves_like 'nil if removed source branch', :ide_edit_path
+
+      it 'returns the merge_request ide route' do
+        expect(entity[:ide_edit_path]).to eq expected_merge_request_path
+      end
+    end
+
+    context 'when source_project and target_project are different' do
+      let(:target_project) { fork_project(source_project, source_project.owner, repository: true) }
+
+      it 'returns the merge_request ide route with the target_project as param' do
+        expect(entity[:ide_edit_path]).to eq("#{expected_merge_request_path}?target_project=#{ERB::Util.url_encode(target_project.full_path)}")
+      end
+    end
+  end
 end