Add latest changes from gitlab-org/gitlab@13-7-stable-eev13.7.0-rc42

3 files changed, 200 insertions, 443 deletions

diff --git a/spec/frontend/diffs/store/actions_spec.js b/spec/frontend/diffs/store/actions_spec.js
index 0af5ddd9764..fef7676e795 100644
--- a/spec/frontend/diffs/store/actions_spec.js
+++ b/spec/frontend/diffs/store/actions_spec.js
@@ -32,7 +32,7 @@ import {
   setHighlightedRow,
   toggleTreeOpen,
   scrollToFile,
-  toggleShowTreeList,
+  setShowTreeList,
   renderFileForDiscussionId,
   setRenderTreeList,
   setShowWhitespace,
@@ -48,6 +48,7 @@ import {
   moveToNeighboringCommit,
   setCurrentDiffFileIdFromNote,
   navigateToDiffFileIndex,
+  setFileByFile,
 } from '~/diffs/store/actions';
 import eventHub from '~/notes/event_hub';
 import * as types from '~/diffs/store/mutation_types';
@@ -159,10 +160,10 @@ describe('DiffsStoreActions', () => {
         .onGet(
           mergeUrlParams(
             {
-              per_page: DIFFS_PER_PAGE,
               w: '1',
               view: 'inline',
               page: 1,
+              per_page: DIFFS_PER_PAGE,
             },
             endpointBatch,
           ),
@@ -171,10 +172,10 @@ describe('DiffsStoreActions', () => {
         .onGet(
           mergeUrlParams(
             {
-              per_page: DIFFS_PER_PAGE,
               w: '1',
               view: 'inline',
               page: 2,
+              per_page: DIFFS_PER_PAGE,
             },
             endpointBatch,
           ),
@@ -248,7 +249,7 @@ describe('DiffsStoreActions', () => {
           { type: types.SET_LOADING, payload: true },
           { type: types.SET_LOADING, payload: false },
           { type: types.SET_MERGE_REQUEST_DIFFS, payload: diffMetadata.merge_request_diffs },
-          { type: types.SET_DIFF_DATA, payload: noFilesData },
+          { type: types.SET_DIFF_METADATA, payload: noFilesData },
         ],
         [],
         () => {
@@ -901,15 +902,22 @@ describe('DiffsStoreActions', () => {
     });
   });
 
-  describe('toggleShowTreeList', () => {
+  describe('setShowTreeList', () => {
     it('commits toggle', done => {
-      testAction(toggleShowTreeList, null, {}, [{ type: types.TOGGLE_SHOW_TREE_LIST }], [], done);
+      testAction(
+        setShowTreeList,
+        { showTreeList: true },
+        {},
+        [{ type: types.SET_SHOW_TREE_LIST, payload: true }],
+        [],
+        done,
+      );
     });
 
     it('updates localStorage', () => {
       jest.spyOn(localStorage, 'setItem').mockImplementation(() => {});
 
-      toggleShowTreeList({ commit() {}, state: { showTreeList: true } });
+      setShowTreeList({ commit() {} }, { showTreeList: true });
 
       expect(localStorage.setItem).toHaveBeenCalledWith('mr_tree_show', true);
     });
@@ -917,7 +925,7 @@ describe('DiffsStoreActions', () => {
     it('does not update localStorage', () => {
       jest.spyOn(localStorage, 'setItem').mockImplementation(() => {});
 
-      toggleShowTreeList({ commit() {}, state: { showTreeList: true } }, false);
+      setShowTreeList({ commit() {} }, { showTreeList: true, saving: false });
 
       expect(localStorage.setItem).not.toHaveBeenCalled();
     });
@@ -1236,10 +1244,6 @@ describe('DiffsStoreActions', () => {
         { diffViewType: 'inline' },
         [
           {
-            type: 'SET_HIDDEN_VIEW_DIFF_FILE_LINES',
-            payload: { filePath: 'path', lines: ['test'] },
-          },
-          {
             type: 'SET_CURRENT_VIEW_DIFF_FILE_LINES',
             payload: { filePath: 'path', lines: ['test'] },
           },
@@ -1259,10 +1263,6 @@ describe('DiffsStoreActions', () => {
         { diffViewType: 'inline' },
         [
           {
-            type: 'SET_HIDDEN_VIEW_DIFF_FILE_LINES',
-            payload: { filePath: 'path', lines },
-          },
-          {
             type: 'SET_CURRENT_VIEW_DIFF_FILE_LINES',
             payload: { filePath: 'path', lines: lines.slice(0, 200) },
           },
@@ -1456,4 +1456,20 @@ describe('DiffsStoreActions', () => {
       );
     });
   });
+
+  describe('setFileByFile', () => {
+    it.each`
+      value
+      ${true}
+      ${false}
+    `('commits SET_FILE_BY_FILE with the new value $value', ({ value }) => {
+      return testAction(
+        setFileByFile,
+        { fileByFile: value },
+        { viewDiffsFileByFile: null },
+        [{ type: types.SET_FILE_BY_FILE, payload: value }],
+        [],
+      );
+    });
+  });
 });
diff --git a/spec/frontend/diffs/store/mutations_spec.js b/spec/frontend/diffs/store/mutations_spec.js
index c0645faf89e..13e7cad835d 100644
--- a/spec/frontend/diffs/store/mutations_spec.js
+++ b/spec/frontend/diffs/store/mutations_spec.js
@@ -1,7 +1,7 @@
 import createState from '~/diffs/store/modules/diff_state';
 import mutations from '~/diffs/store/mutations';
 import * as types from '~/diffs/store/mutation_types';
-import { INLINE_DIFF_VIEW_TYPE } from '~/diffs/constants';
+import { INLINE_DIFF_VIEW_TYPE, INLINE_DIFF_LINES_KEY } from '~/diffs/constants';
 import diffFileMockData from '../mock_data/diff_file';
 import * as utils from '~/diffs/store/utils';
 
@@ -67,28 +67,28 @@ describe('DiffsStoreMutations', () => {
     });
   });
 
-  describe('SET_DIFF_DATA', () => {
-    it('should not modify the existing state', () => {
+  describe('SET_DIFF_METADATA', () => {
+    it('should overwrite state with the camelCased data that is passed in', () => {
       const state = {
-        diffFiles: [
-          {
-            content_sha: diffFileMockData.content_sha,
-            file_hash: diffFileMockData.file_hash,
-            highlighted_diff_lines: [],
-          },
-        ],
+        diffFiles: [],
       };
       const diffMock = {
         diff_files: [diffFileMockData],
       };
+      const metaMock = {
+        other_key: 'value',
+      };
 
-      mutations[types.SET_DIFF_DATA](state, diffMock);
+      mutations[types.SET_DIFF_METADATA](state, diffMock);
+      expect(state.diffFiles[0]).toEqual(diffFileMockData);
 
-      expect(state.diffFiles[0].parallel_diff_lines).toBeUndefined();
+      mutations[types.SET_DIFF_METADATA](state, metaMock);
+      expect(state.diffFiles[0]).toEqual(diffFileMockData);
+      expect(state.otherKey).toEqual('value');
     });
   });
 
-  describe('SET_DIFFSET_DIFF_DATA_BATCH_DATA', () => {
+  describe('SET_DIFF_DATA_BATCH_DATA', () => {
     it('should set diff data batch type properly', () => {
       const state = { diffFiles: [] };
       const diffMock = {
@@ -97,9 +97,6 @@ describe('DiffsStoreMutations', () => {
 
       mutations[types.SET_DIFF_DATA_BATCH](state, diffMock);
 
-      const firstLine = state.diffFiles[0].parallel_diff_lines[0];
-
-      expect(firstLine.right.text).toBeUndefined();
       expect(state.diffFiles[0].renderIt).toEqual(true);
       expect(state.diffFiles[0].collapsed).toEqual(false);
     });
@@ -142,8 +139,7 @@ describe('DiffsStoreMutations', () => {
       };
       const diffFile = {
         file_hash: options.fileHash,
-        highlighted_diff_lines: [],
-        parallel_diff_lines: [],
+        [INLINE_DIFF_LINES_KEY]: [],
       };
       const state = { diffFiles: [diffFile], diffViewType: 'viewType' };
       const lines = [{ old_line: 1, new_line: 1 }];
@@ -171,9 +167,7 @@ describe('DiffsStoreMutations', () => {
       );
 
       expect(utils.addContextLines).toHaveBeenCalledWith({
-        inlineLines: diffFile.highlighted_diff_lines,
-        parallelLines: diffFile.parallel_diff_lines,
-        diffViewType: 'viewType',
+        inlineLines: diffFile[INLINE_DIFF_LINES_KEY],
         contextLines: options.contextLines,
         bottom: options.params.bottom,
         lineNumbers: options.lineNumbers,
@@ -225,19 +219,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-                right: {
-                  line_code: 'ABC_2',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [],
@@ -267,12 +249,8 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].right.discussions).toEqual([]);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toEqual(1);
     });
 
     it('should not duplicate discussions on line', () => {
@@ -291,19 +269,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-                right: {
-                  line_code: 'ABC_2',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [],
@@ -333,24 +299,16 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].right.discussions).toEqual([]);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toEqual(1);
 
       mutations[types.SET_LINE_DISCUSSIONS_FOR_FILE](state, {
         discussion,
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].right.discussions).toEqual([]);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toEqual(1);
     });
 
     it('updates existing discussion', () => {
@@ -369,19 +327,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-                right: {
-                  line_code: 'ABC_2',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [],
@@ -411,12 +357,8 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].right.discussions).toEqual([]);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toEqual(1);
 
       mutations[types.SET_LINE_DISCUSSIONS_FOR_FILE](state, {
         discussion: {
@@ -427,11 +369,8 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].notes.length).toBe(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].notes.length).toBe(1);
-
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].resolved).toBe(true);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].resolved).toBe(true);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].notes.length).toBe(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].resolved).toBe(true);
     });
 
     it('should not duplicate inline diff discussions', () => {
@@ -450,7 +389,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [
@@ -472,7 +411,6 @@ describe('DiffsStoreMutations', () => {
                 discussions: [],
               },
             ],
-            parallel_diff_lines: [],
           },
         ],
       };
@@ -497,7 +435,7 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toBe(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toBe(1);
     });
 
     it('should add legacy discussions to the given line', () => {
@@ -517,19 +455,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-                right: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [],
@@ -557,11 +483,8 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toEqual(1);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toEqual(1);
     });
 
     it('should add discussions by line_codes and positions attributes', () => {
@@ -580,19 +503,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-                right: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [],
@@ -624,11 +535,8 @@ describe('DiffsStoreMutations', () => {
         diffPositionByLineCode,
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions).toHaveLength(1);
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions[0].id).toBe(1);
-
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions).toHaveLength(1);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions[0].id).toBe(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions).toHaveLength(1);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions[0].id).toBe(1);
     });
 
     it('should add discussion to file', () => {
@@ -638,8 +546,7 @@ describe('DiffsStoreMutations', () => {
           {
             file_hash: 'ABC',
             discussions: [],
-            parallel_diff_lines: [],
-            highlighted_diff_lines: [],
+            [INLINE_DIFF_LINES_KEY]: [],
           },
         ],
       };
@@ -668,30 +575,7 @@ describe('DiffsStoreMutations', () => {
         diffFiles: [
           {
             file_hash: 'ABC',
-            parallel_diff_lines: [
-              {
-                left: {
-                  line_code: 'ABC_1',
-                  discussions: [
-                    {
-                      id: 1,
-                      line_code: 'ABC_1',
-                      notes: [],
-                    },
-                    {
-                      id: 2,
-                      line_code: 'ABC_1',
-                      notes: [],
-                    },
-                  ],
-                },
-                right: {
-                  line_code: 'ABC_1',
-                  discussions: [],
-                },
-              },
-            ],
-            highlighted_diff_lines: [
+            [INLINE_DIFF_LINES_KEY]: [
               {
                 line_code: 'ABC_1',
                 discussions: [
@@ -717,8 +601,7 @@ describe('DiffsStoreMutations', () => {
         lineCode: 'ABC_1',
       });
 
-      expect(state.diffFiles[0].parallel_diff_lines[0].left.discussions.length).toEqual(0);
-      expect(state.diffFiles[0].highlighted_diff_lines[0].discussions.length).toEqual(0);
+      expect(state.diffFiles[0][INLINE_DIFF_LINES_KEY][0].discussions.length).toEqual(0);
     });
   });
 
@@ -738,15 +621,11 @@ describe('DiffsStoreMutations', () => {
     });
   });
 
-  describe('TOGGLE_SHOW_TREE_LIST', () => {
-    it('toggles showTreeList', () => {
+  describe('SET_SHOW_TREE_LIST', () => {
+    it('sets showTreeList', () => {
       const state = createState();
 
-      mutations[types.TOGGLE_SHOW_TREE_LIST](state);
-
-      expect(state.showTreeList).toBe(false, 'Failed to toggle showTreeList to false');
-
-      mutations[types.TOGGLE_SHOW_TREE_LIST](state);
+      mutations[types.SET_SHOW_TREE_LIST](state, true);
 
       expect(state.showTreeList).toBe(true, 'Failed to toggle showTreeList to true');
     });
@@ -776,11 +655,7 @@ describe('DiffsStoreMutations', () => {
     it('sets hasForm on lines', () => {
       const file = {
         file_hash: 'hash',
-        parallel_diff_lines: [
-          { left: { line_code: '123', hasForm: false }, right: {} },
-          { left: {}, right: { line_code: '124', hasForm: false } },
-        ],
-        highlighted_diff_lines: [
+        [INLINE_DIFF_LINES_KEY]: [
           { line_code: '123', hasForm: false },
           { line_code: '124', hasForm: false },
         ],
@@ -795,11 +670,8 @@ describe('DiffsStoreMutations', () => {
         fileHash: 'hash',
       });
 
-      expect(file.highlighted_diff_lines[0].hasForm).toBe(true);
-      expect(file.highlighted_diff_lines[1].hasForm).toBe(false);
-
-      expect(file.parallel_diff_lines[0].left.hasForm).toBe(true);
-      expect(file.parallel_diff_lines[1].right.hasForm).toBe(false);
+      expect(file[INLINE_DIFF_LINES_KEY][0].hasForm).toBe(true);
+      expect(file[INLINE_DIFF_LINES_KEY][1].hasForm).toBe(false);
     });
   });
 
@@ -885,8 +757,7 @@ describe('DiffsStoreMutations', () => {
             file_path: 'test',
             isLoadingFullFile: true,
             isShowingFullFile: false,
-            highlighted_diff_lines: [],
-            parallel_diff_lines: [],
+            [INLINE_DIFF_LINES_KEY]: [],
           },
         ],
       };
@@ -903,8 +774,7 @@ describe('DiffsStoreMutations', () => {
             file_path: 'test',
             isLoadingFullFile: true,
             isShowingFullFile: false,
-            highlighted_diff_lines: [],
-            parallel_diff_lines: [],
+            [INLINE_DIFF_LINES_KEY]: [],
           },
         ],
       };
@@ -927,80 +797,42 @@ describe('DiffsStoreMutations', () => {
     });
   });
 
-  describe('SET_HIDDEN_VIEW_DIFF_FILE_LINES', () => {
-    [
-      { current: 'highlighted', hidden: 'parallel', diffViewType: 'inline' },
-      { current: 'parallel', hidden: 'highlighted', diffViewType: 'parallel' },
-    ].forEach(({ current, hidden, diffViewType }) => {
-      it(`sets the ${hidden} lines when diff view is ${diffViewType}`, () => {
-        const file = { file_path: 'test', parallel_diff_lines: [], highlighted_diff_lines: [] };
-        const state = {
-          diffFiles: [file],
-          diffViewType,
-        };
-
-        mutations[types.SET_HIDDEN_VIEW_DIFF_FILE_LINES](state, {
-          filePath: 'test',
-          lines: ['test'],
-        });
-
-        expect(file[`${current}_diff_lines`]).toEqual([]);
-        expect(file[`${hidden}_diff_lines`]).toEqual(['test']);
-      });
-    });
-  });
-
   describe('SET_CURRENT_VIEW_DIFF_FILE_LINES', () => {
-    [
-      { current: 'highlighted', hidden: 'parallel', diffViewType: 'inline' },
-      { current: 'parallel', hidden: 'highlighted', diffViewType: 'parallel' },
-    ].forEach(({ current, hidden, diffViewType }) => {
-      it(`sets the ${current} lines when diff view is ${diffViewType}`, () => {
-        const file = { file_path: 'test', parallel_diff_lines: [], highlighted_diff_lines: [] };
-        const state = {
-          diffFiles: [file],
-          diffViewType,
-        };
-
-        mutations[types.SET_CURRENT_VIEW_DIFF_FILE_LINES](state, {
-          filePath: 'test',
-          lines: ['test'],
-        });
-
-        expect(file[`${current}_diff_lines`]).toEqual(['test']);
-        expect(file[`${hidden}_diff_lines`]).toEqual([]);
+    it(`sets the highlighted lines`, () => {
+      const file = { file_path: 'test', [INLINE_DIFF_LINES_KEY]: [] };
+      const state = {
+        diffFiles: [file],
+      };
+
+      mutations[types.SET_CURRENT_VIEW_DIFF_FILE_LINES](state, {
+        filePath: 'test',
+        lines: ['test'],
       });
+
+      expect(file[INLINE_DIFF_LINES_KEY]).toEqual(['test']);
     });
   });
 
   describe('ADD_CURRENT_VIEW_DIFF_FILE_LINES', () => {
-    [
-      { current: 'highlighted', hidden: 'parallel', diffViewType: 'inline' },
-      { current: 'parallel', hidden: 'highlighted', diffViewType: 'parallel' },
-    ].forEach(({ current, hidden, diffViewType }) => {
-      it(`pushes to ${current} lines when diff view is ${diffViewType}`, () => {
-        const file = { file_path: 'test', parallel_diff_lines: [], highlighted_diff_lines: [] };
-        const state = {
-          diffFiles: [file],
-          diffViewType,
-        };
-
-        mutations[types.ADD_CURRENT_VIEW_DIFF_FILE_LINES](state, {
-          filePath: 'test',
-          line: 'test',
-        });
-
-        expect(file[`${current}_diff_lines`]).toEqual(['test']);
-        expect(file[`${hidden}_diff_lines`]).toEqual([]);
-
-        mutations[types.ADD_CURRENT_VIEW_DIFF_FILE_LINES](state, {
-          filePath: 'test',
-          line: 'test2',
-        });
-
-        expect(file[`${current}_diff_lines`]).toEqual(['test', 'test2']);
-        expect(file[`${hidden}_diff_lines`]).toEqual([]);
+    it('pushes to inline lines', () => {
+      const file = { file_path: 'test', [INLINE_DIFF_LINES_KEY]: [] };
+      const state = {
+        diffFiles: [file],
+      };
+
+      mutations[types.ADD_CURRENT_VIEW_DIFF_FILE_LINES](state, {
+        filePath: 'test',
+        line: 'test',
+      });
+
+      expect(file[INLINE_DIFF_LINES_KEY]).toEqual(['test']);
+
+      mutations[types.ADD_CURRENT_VIEW_DIFF_FILE_LINES](state, {
+        filePath: 'test',
+        line: 'test2',
       });
+
+      expect(file[INLINE_DIFF_LINES_KEY]).toEqual(['test', 'test2']);
     });
   });
 
@@ -1060,4 +892,18 @@ describe('DiffsStoreMutations', () => {
       expect(state.showSuggestPopover).toBe(false);
     });
   });
+
+  describe('SET_FILE_BY_FILE', () => {
+    it.each`
+      value    | opposite
+      ${true}  | ${false}
+      ${false} | ${true}
+    `('sets viewDiffsFileByFile to $value', ({ value, opposite }) => {
+      const state = { viewDiffsFileByFile: opposite };
+
+      mutations[types.SET_FILE_BY_FILE](state, value);
+
+      expect(state.viewDiffsFileByFile).toBe(value);
+    });
+  });
 });
diff --git a/spec/frontend/diffs/store/utils_spec.js b/spec/frontend/diffs/store/utils_spec.js
index 866be0abd22..7ee97224707 100644
--- a/spec/frontend/diffs/store/utils_spec.js
+++ b/spec/frontend/diffs/store/utils_spec.js
@@ -10,7 +10,7 @@ import {
   OLD_LINE_TYPE,
   MATCH_LINE_TYPE,
   INLINE_DIFF_VIEW_TYPE,
-  PARALLEL_DIFF_VIEW_TYPE,
+  INLINE_DIFF_LINES_KEY,
 } from '~/diffs/constants';
 import { MERGE_REQUEST_NOTEABLE_TYPE } from '~/notes/constants';
 import diffFileMockData from '../mock_data/diff_file';
@@ -20,14 +20,6 @@ import { noteableDataMock } from '../../notes/mock_data';
 const getDiffFileMock = () => JSON.parse(JSON.stringify(diffFileMockData));
 const getDiffMetadataMock = () => JSON.parse(JSON.stringify(diffMetadata));
 
-function extractLinesFromFile(file) {
-  const unpackedParallel = file.parallel_diff_lines
-    .flatMap(({ left, right }) => [left, right])
-    .filter(Boolean);
-
-  return [...file.highlighted_diff_lines, ...unpackedParallel];
-}
-
 describe('DiffsStoreUtils', () => {
   describe('findDiffFile', () => {
     const files = [{ file_hash: 1, name: 'one' }];
@@ -45,7 +37,7 @@ describe('DiffsStoreUtils', () => {
     });
   });
 
-  describe('findIndexInInlineLines and findIndexInParallelLines', () => {
+  describe('findIndexInInlineLines', () => {
     const expectSet = (method, lines, invalidLines) => {
       expect(method(lines, { oldLineNumber: 3, newLineNumber: 5 })).toEqual(4);
       expect(method(invalidLines || lines, { oldLineNumber: 32, newLineNumber: 53 })).toEqual(-1);
@@ -53,44 +45,26 @@ describe('DiffsStoreUtils', () => {
 
     describe('findIndexInInlineLines', () => {
       it('should return correct index for given line numbers', () => {
-        expectSet(utils.findIndexInInlineLines, getDiffFileMock().highlighted_diff_lines);
-      });
-    });
-
-    describe('findIndexInParallelLines', () => {
-      it('should return correct index for given line numbers', () => {
-        expectSet(utils.findIndexInParallelLines, getDiffFileMock().parallel_diff_lines, []);
+        expectSet(utils.findIndexInInlineLines, getDiffFileMock()[INLINE_DIFF_LINES_KEY]);
       });
     });
   });
 
   describe('getPreviousLineIndex', () => {
-    [
-      { diffViewType: INLINE_DIFF_VIEW_TYPE, file: { parallel_diff_lines: [] } },
-      { diffViewType: PARALLEL_DIFF_VIEW_TYPE, file: { highlighted_diff_lines: [] } },
-    ].forEach(({ diffViewType, file }) => {
-      describe(`with diffViewType (${diffViewType}) in split diffs`, () => {
-        let diffFile;
-
-        beforeEach(() => {
-          diffFile = { ...clone(diffFileMockData), ...file };
-        });
+    describe(`with diffViewType (inline) in split diffs`, () => {
+      let diffFile;
 
-        it('should return the correct previous line number', () => {
-          const emptyLines =
-            diffViewType === INLINE_DIFF_VIEW_TYPE
-              ? diffFile.parallel_diff_lines
-              : diffFile.highlighted_diff_lines;
-
-          // This expectation asserts that we cannot possibly be using the opposite view type lines in the next expectation
-          expect(emptyLines.length).toBe(0);
-          expect(
-            utils.getPreviousLineIndex(diffViewType, diffFile, {
-              oldLineNumber: 3,
-              newLineNumber: 5,
-            }),
-          ).toBe(4);
-        });
+      beforeEach(() => {
+        diffFile = { ...clone(diffFileMockData) };
+      });
+
+      it('should return the correct previous line number', () => {
+        expect(
+          utils.getPreviousLineIndex(INLINE_DIFF_VIEW_TYPE, diffFile, {
+            oldLineNumber: 3,
+            newLineNumber: 5,
+          }),
+        ).toBe(4);
       });
     });
   });
@@ -100,82 +74,50 @@ describe('DiffsStoreUtils', () => {
       const diffFile = getDiffFileMock();
       const lineNumbers = { oldLineNumber: 3, newLineNumber: 5 };
       const inlineIndex = utils.findIndexInInlineLines(
-        diffFile.highlighted_diff_lines,
+        diffFile[INLINE_DIFF_LINES_KEY],
         lineNumbers,
       );
-      const parallelIndex = utils.findIndexInParallelLines(
-        diffFile.parallel_diff_lines,
-        lineNumbers,
-      );
-      const atInlineIndex = diffFile.highlighted_diff_lines[inlineIndex];
-      const atParallelIndex = diffFile.parallel_diff_lines[parallelIndex];
+      const atInlineIndex = diffFile[INLINE_DIFF_LINES_KEY][inlineIndex];
 
       utils.removeMatchLine(diffFile, lineNumbers, false);
 
-      expect(diffFile.highlighted_diff_lines[inlineIndex]).not.toEqual(atInlineIndex);
-      expect(diffFile.parallel_diff_lines[parallelIndex]).not.toEqual(atParallelIndex);
+      expect(diffFile[INLINE_DIFF_LINES_KEY][inlineIndex]).not.toEqual(atInlineIndex);
 
       utils.removeMatchLine(diffFile, lineNumbers, true);
 
-      expect(diffFile.highlighted_diff_lines[inlineIndex + 1]).not.toEqual(atInlineIndex);
-      expect(diffFile.parallel_diff_lines[parallelIndex + 1]).not.toEqual(atParallelIndex);
+      expect(diffFile[INLINE_DIFF_LINES_KEY][inlineIndex + 1]).not.toEqual(atInlineIndex);
     });
   });
 
   describe('addContextLines', () => {
-    [INLINE_DIFF_VIEW_TYPE, PARALLEL_DIFF_VIEW_TYPE].forEach(diffViewType => {
-      it(`should add context lines for ${diffViewType}`, () => {
-        const diffFile = getDiffFileMock();
-        const inlineLines = diffFile.highlighted_diff_lines;
-        const parallelLines = diffFile.parallel_diff_lines;
-        const lineNumbers = { oldLineNumber: 3, newLineNumber: 5 };
-        const contextLines = [{ lineNumber: 42, line_code: '123' }];
-        const options = { inlineLines, parallelLines, contextLines, lineNumbers, diffViewType };
-        const inlineIndex = utils.findIndexInInlineLines(inlineLines, lineNumbers);
-        const parallelIndex = utils.findIndexInParallelLines(parallelLines, lineNumbers);
-        const normalizedParallelLine = {
-          left: options.contextLines[0],
-          right: options.contextLines[0],
-          line_code: '123',
-        };
+    it(`should add context lines`, () => {
+      const diffFile = getDiffFileMock();
+      const inlineLines = diffFile[INLINE_DIFF_LINES_KEY];
+      const lineNumbers = { oldLineNumber: 3, newLineNumber: 5 };
+      const contextLines = [{ lineNumber: 42, line_code: '123' }];
+      const options = { inlineLines, contextLines, lineNumbers };
+      const inlineIndex = utils.findIndexInInlineLines(inlineLines, lineNumbers);
 
-        utils.addContextLines(options);
+      utils.addContextLines(options);
 
-        if (diffViewType === INLINE_DIFF_VIEW_TYPE) {
-          expect(inlineLines[inlineIndex]).toEqual(contextLines[0]);
-        } else {
-          expect(parallelLines[parallelIndex]).toEqual(normalizedParallelLine);
-        }
-      });
+      expect(inlineLines[inlineIndex]).toEqual(contextLines[0]);
+    });
 
-      it(`should add context lines properly with bottom parameter for ${diffViewType}`, () => {
-        const diffFile = getDiffFileMock();
-        const inlineLines = diffFile.highlighted_diff_lines;
-        const parallelLines = diffFile.parallel_diff_lines;
-        const lineNumbers = { oldLineNumber: 3, newLineNumber: 5 };
-        const contextLines = [{ lineNumber: 42, line_code: '123' }];
-        const options = {
-          inlineLines,
-          parallelLines,
-          contextLines,
-          lineNumbers,
-          bottom: true,
-          diffViewType,
-        };
-        const normalizedParallelLine = {
-          left: options.contextLines[0],
-          right: options.contextLines[0],
-          line_code: '123',
-        };
+    it(`should add context lines properly with bottom parameter`, () => {
+      const diffFile = getDiffFileMock();
+      const inlineLines = diffFile[INLINE_DIFF_LINES_KEY];
+      const lineNumbers = { oldLineNumber: 3, newLineNumber: 5 };
+      const contextLines = [{ lineNumber: 42, line_code: '123' }];
+      const options = {
+        inlineLines,
+        contextLines,
+        lineNumbers,
+        bottom: true,
+      };
 
-        utils.addContextLines(options);
+      utils.addContextLines(options);
 
-        if (diffViewType === INLINE_DIFF_VIEW_TYPE) {
-          expect(inlineLines[inlineLines.length - 1]).toEqual(contextLines[0]);
-        } else {
-          expect(parallelLines[parallelLines.length - 1]).toEqual(normalizedParallelLine);
-        }
-      });
+      expect(inlineLines[inlineLines.length - 1]).toEqual(contextLines[0]);
     });
   });
 
@@ -195,7 +137,6 @@ describe('DiffsStoreUtils', () => {
           new_line: 3,
           old_line: 1,
         },
-        diffViewType: PARALLEL_DIFF_VIEW_TYPE,
         linePosition: LINE_POSITION_LEFT,
         lineRange: { start_line_code: 'abc_1_1', end_line_code: 'abc_2_2' },
       };
@@ -256,7 +197,6 @@ describe('DiffsStoreUtils', () => {
           new_line: 3,
           old_line: 1,
         },
-        diffViewType: PARALLEL_DIFF_VIEW_TYPE,
         linePosition: LINE_POSITION_LEFT,
       };
 
@@ -424,20 +364,6 @@ describe('DiffsStoreUtils', () => {
       expect(preppedLine).toEqual(correctLine);
     });
 
-    it('returns a nested object with "left" and "right" lines + the line code for `parallel` lines', () => {
-      preppedLine = utils.prepareLineForRenamedFile({
-        diffViewType: PARALLEL_DIFF_VIEW_TYPE,
-        line: sourceLine,
-        index: lineIndex,
-        diffFile,
-      });
-
-      expect(Object.keys(preppedLine)).toEqual(['left', 'right', 'line_code']);
-      expect(preppedLine.left).toEqual(correctLine);
-      expect(preppedLine.right).toEqual(correctLine);
-      expect(preppedLine.line_code).toEqual(correctLine.line_code);
-    });
-
     it.each`
       brokenSymlink
       ${false}
@@ -474,35 +400,26 @@ describe('DiffsStoreUtils', () => {
 
         preparedDiff = { diff_files: [mock] };
         splitInlineDiff = {
-          diff_files: [{ ...mock, parallel_diff_lines: undefined }],
+          diff_files: [{ ...mock }],
         };
         splitParallelDiff = {
-          diff_files: [{ ...mock, highlighted_diff_lines: undefined }],
+          diff_files: [{ ...mock, [INLINE_DIFF_LINES_KEY]: undefined }],
         };
         completedDiff = {
-          diff_files: [{ ...mock, highlighted_diff_lines: undefined }],
+          diff_files: [{ ...mock, [INLINE_DIFF_LINES_KEY]: undefined }],
         };
 
-        preparedDiff.diff_files = utils.prepareDiffData(preparedDiff);
-        splitInlineDiff.diff_files = utils.prepareDiffData(splitInlineDiff);
-        splitParallelDiff.diff_files = utils.prepareDiffData(splitParallelDiff);
-        completedDiff.diff_files = utils.prepareDiffData(completedDiff, [mock]);
+        preparedDiff.diff_files = utils.prepareDiffData({ diff: preparedDiff });
+        splitInlineDiff.diff_files = utils.prepareDiffData({ diff: splitInlineDiff });
+        splitParallelDiff.diff_files = utils.prepareDiffData({ diff: splitParallelDiff });
+        completedDiff.diff_files = utils.prepareDiffData({
+          diff: completedDiff,
+          priorFiles: [mock],
+        });
       });
 
       it('sets the renderIt and collapsed attribute on files', () => {
-        const firstParallelDiffLine = preparedDiff.diff_files[0].parallel_diff_lines[2];
-
-        expect(firstParallelDiffLine.left.discussions.length).toBe(0);
-        expect(firstParallelDiffLine.left).not.toHaveAttr('text');
-        expect(firstParallelDiffLine.right.discussions.length).toBe(0);
-        expect(firstParallelDiffLine.right).not.toHaveAttr('text');
-        const firstParallelChar = firstParallelDiffLine.right.rich_text.charAt(0);
-
-        expect(firstParallelChar).not.toBe(' ');
-        expect(firstParallelChar).not.toBe('+');
-        expect(firstParallelChar).not.toBe('-');
-
-        const checkLine = preparedDiff.diff_files[0].highlighted_diff_lines[0];
+        const checkLine = preparedDiff.diff_files[0][INLINE_DIFF_LINES_KEY][0];
 
         expect(checkLine.discussions.length).toBe(0);
         expect(checkLine).not.toHaveAttr('text');
@@ -516,29 +433,14 @@ describe('DiffsStoreUtils', () => {
         expect(preparedDiff.diff_files[0].collapsed).toBeFalsy();
       });
 
-      it('adds line_code to all lines', () => {
-        expect(
-          preparedDiff.diff_files[0].parallel_diff_lines.filter(line => !line.line_code),
-        ).toHaveLength(0);
-      });
-
-      it('uses right line code if left has none', () => {
-        const firstLine = preparedDiff.diff_files[0].parallel_diff_lines[0];
-
-        expect(firstLine.line_code).toEqual(firstLine.right.line_code);
-      });
-
       it('guarantees an empty array for both diff styles', () => {
-        expect(splitInlineDiff.diff_files[0].parallel_diff_lines.length).toEqual(0);
-        expect(splitInlineDiff.diff_files[0].highlighted_diff_lines.length).toBeGreaterThan(0);
-        expect(splitParallelDiff.diff_files[0].parallel_diff_lines.length).toBeGreaterThan(0);
-        expect(splitParallelDiff.diff_files[0].highlighted_diff_lines.length).toEqual(0);
+        expect(splitInlineDiff.diff_files[0][INLINE_DIFF_LINES_KEY].length).toBeGreaterThan(0);
+        expect(splitParallelDiff.diff_files[0][INLINE_DIFF_LINES_KEY].length).toEqual(0);
       });
 
       it('merges existing diff files with newly loaded diff files to ensure split diffs are eventually completed', () => {
         expect(completedDiff.diff_files.length).toEqual(1);
-        expect(completedDiff.diff_files[0].parallel_diff_lines.length).toBeGreaterThan(0);
-        expect(completedDiff.diff_files[0].highlighted_diff_lines.length).toBeGreaterThan(0);
+        expect(completedDiff.diff_files[0][INLINE_DIFF_LINES_KEY].length).toBeGreaterThan(0);
       });
 
       it('leaves files in the existing state', () => {
@@ -548,20 +450,26 @@ describe('DiffsStoreUtils', () => {
           content_sha: 'ABC',
           file_hash: 'DEF',
         };
-        const updatedFilesList = utils.prepareDiffData({ diff_files: [fakeNewFile] }, priorFiles);
+        const updatedFilesList = utils.prepareDiffData({
+          diff: { diff_files: [fakeNewFile] },
+          priorFiles,
+        });
 
         expect(updatedFilesList).toEqual([mock, fakeNewFile]);
       });
 
       it('completes an existing split diff without overwriting existing diffs', () => {
         // The current state has a file that has only loaded inline lines
-        const priorFiles = [{ ...mock, parallel_diff_lines: [] }];
+        const priorFiles = [{ ...mock }];
         // The next (batch) load loads two files: the other half of that file, and a new file
         const fakeBatch = [
-          { ...mock, highlighted_diff_lines: undefined },
-          { ...mock, highlighted_diff_lines: undefined, content_sha: 'ABC', file_hash: 'DEF' },
+          { ...mock, [INLINE_DIFF_LINES_KEY]: undefined },
+          { ...mock, [INLINE_DIFF_LINES_KEY]: undefined, content_sha: 'ABC', file_hash: 'DEF' },
         ];
-        const updatedFilesList = utils.prepareDiffData({ diff_files: fakeBatch }, priorFiles);
+        const updatedFilesList = utils.prepareDiffData({
+          diff: { diff_files: fakeBatch },
+          priorFiles,
+        });
 
         expect(updatedFilesList).toEqual([
           mock,
@@ -584,7 +492,7 @@ describe('DiffsStoreUtils', () => {
           ...splitInlineDiff.diff_files,
           ...splitParallelDiff.diff_files,
           ...completedDiff.diff_files,
-        ].flatMap(file => extractLinesFromFile(file));
+        ].flatMap(file => [...file[INLINE_DIFF_LINES_KEY]]);
 
         lines.forEach(line => {
           expect(line.commentsDisabled).toBe(false);
@@ -599,7 +507,7 @@ describe('DiffsStoreUtils', () => {
       beforeEach(() => {
         mock = getDiffMetadataMock();
 
-        preparedDiffFiles = utils.prepareDiffData(mock);
+        preparedDiffFiles = utils.prepareDiffData({ diff: mock, meta: true });
       });
 
       it('sets the renderIt and collapsed attribute on files', () => {
@@ -608,15 +516,14 @@ describe('DiffsStoreUtils', () => {
       });
 
       it('guarantees an empty array of lines for both diff styles', () => {
-        expect(preparedDiffFiles[0].parallel_diff_lines.length).toEqual(0);
-        expect(preparedDiffFiles[0].highlighted_diff_lines.length).toEqual(0);
+        expect(preparedDiffFiles[0][INLINE_DIFF_LINES_KEY].length).toEqual(0);
       });
 
       it('leaves files in the existing state', () => {
         const fileMock = getDiffFileMock();
         const metaData = getDiffMetadataMock();
         const priorFiles = [fileMock];
-        const updatedFilesList = utils.prepareDiffData(metaData, priorFiles);
+        const updatedFilesList = utils.prepareDiffData({ diff: metaData, priorFiles, meta: true });
 
         expect(updatedFilesList.length).toEqual(2);
         expect(updatedFilesList[0]).toEqual(fileMock);
@@ -641,14 +548,13 @@ describe('DiffsStoreUtils', () => {
         const fileMock = getDiffFileMock();
         const metaMock = getDiffMetadataMock();
         const priorFiles = [{ ...fileMock }];
-        const updatedFilesList = utils.prepareDiffData(metaMock, priorFiles);
+        const updatedFilesList = utils.prepareDiffData({ diff: metaMock, priorFiles, meta: true });
 
         expect(updatedFilesList).toEqual([
           fileMock,
           {
             ...metaMock.diff_files[0],
-            highlighted_diff_lines: [],
-            parallel_diff_lines: [],
+            [INLINE_DIFF_LINES_KEY]: [],
           },
         ]);
       });
@@ -1217,30 +1123,19 @@ describe('DiffsStoreUtils', () => {
     it('converts inline diff lines to parallel diff lines', () => {
       const file = getDiffFileMock();
 
-      expect(utils.parallelizeDiffLines(file.highlighted_diff_lines)).toEqual(
+      expect(utils.parallelizeDiffLines(file[INLINE_DIFF_LINES_KEY])).toEqual(
         file.parallel_diff_lines,
       );
     });
 
-    /**
-     * What's going on here?
-     *
-     * The inline version of parallelizeDiffLines simply keeps the difflines
-     * in the same order they are received as opposed to shuffling them
-     * to be "side by side".
-     *
-     * This keeps the underlying data structure the same which simplifies
-     * the components, but keeps the changes grouped together as users
-     * expect when viewing changes inline.
-     */
-    it('converts inline diff lines to inline diff lines with a parallel structure', () => {
+    it('converts inline diff lines', () => {
       const file = getDiffFileMock();
       const files = utils.parallelizeDiffLines(file.highlighted_diff_lines, true);
 
       expect(files[5].left).toEqual(file.parallel_diff_lines[5].left);
       expect(files[5].right).toBeNull();
-      expect(files[6].left).toBeNull();
-      expect(files[6].right).toEqual(file.parallel_diff_lines[5].right);
+      expect(files[6].left).toEqual(file.parallel_diff_lines[5].right);
+      expect(files[6].right).toBeNull();
     });
   });
 });