Add a UUID to each Diff File when the raw data is processed

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

@@ -16,6 +16,7 @@ import {
   INLINE_DIFF_VIEW_TYPE,
   PARALLEL_DIFF_VIEW_TYPE,
 } from '../constants';
+import { uuids } from '../utils/uuids';
 
 export function findDiffFile(files, match, matchKey = 'file_hash') {
   return files.find(file => file[matchKey] === match);
@@ -403,8 +404,26 @@ function deduplicateFilesList(files) {
   return Object.values(dedupedFiles);
 }
 
+function prepareDiffFile(file) {
+  Object.assign(file, {
+    uuid: uuids({
+      seeds: [
+        file.blob.id,
+        file.diff_refs.base_sha,
+        file.diff_refs.start_sha,
+        file.diff_refs.head_sha,
+        file.file_identifier_hash,
+        Number(file.blob.mode),
+      ],
+    })[0],
+  });
+
+  return file;
+}
+
 export function prepareDiffData(diff, priorFiles = []) {
   const cleanedFiles = (diff.diff_files || [])
+    .map(prepareDiffFile)
     .map(ensureBasicDiffFileLines)
     .map(prepareDiffFileLines)
     .map(finalizeDiffFile);

spec/frontend/diffs/mock_data/diff_file.js

@@ -13,6 +13,7 @@ export default {
   blob_name: 'CHANGELOG',
   blob_icon: '<i aria-hidden="true" data-hidden="true" class="fa fa-file-text-o fa-fw"></i>',
   file_hash: '1c497fbb3a46b78edf04cc2a2fa33f67e3ffbe2a',
+  file_identifier_hash: '928f8286952bda02d674b692addcbe077084663a',
   file_path: 'CHANGELOG',
   new_file: false,
   deleted_file: false,

spec/frontend/diffs/store/mutations_spec.js

@@ -243,6 +243,8 @@ describe('DiffsStoreMutations', () => {
       const data = {
         diff_files: [
           {
+            blob: {},
+            diff_refs: {},
             content_sha: 'abc',
             file_hash: fileHash,
             extra_field: 1,

spec/frontend/diffs/store/utils_spec.js

 import { clone } from 'lodash';
 import * as utils from '~/diffs/store/utils';
+import { uuids } from '~/diffs/utils/uuids';
 import {
   LINE_POSITION_LEFT,
   LINE_POSITION_RIGHT,
@@ -430,6 +431,7 @@ describe('DiffsStoreUtils', () => {
   });
 
   describe('prepareDiffData', () => {
+    let fileId;
     let mock;
     let preparedDiff;
     let splitInlineDiff;
@@ -438,6 +440,17 @@ describe('DiffsStoreUtils', () => {
 
     beforeEach(() => {
       mock = getDiffFileMock();
+      [fileId] = uuids({
+        seeds: [
+          mock.blob.id,
+          mock.diff_refs.base_sha,
+          mock.diff_refs.start_sha,
+          mock.diff_refs.head_sha,
+          mock.file_identifier_hash,
+          Number(mock.blob.mode),
+        ],
+      });
+
       preparedDiff = { diff_files: [mock] };
       splitInlineDiff = {
         diff_files: [{ ...mock, parallel_diff_lines: undefined }],
@@ -455,6 +468,13 @@ describe('DiffsStoreUtils', () => {
       completedDiff.diff_files = utils.prepareDiffData(completedDiff, [mock]);
     });
 
+    it('adds a universally unique identifier to each diff file', () => {
+      expect(preparedDiff.diff_files[0].uuid).toBe(fileId);
+      expect(splitInlineDiff.diff_files[0].uuid).toBe(fileId);
+      expect(splitParallelDiff.diff_files[0].uuid).toBe(fileId);
+      expect(completedDiff.diff_files[0].uuid).toBe(fileId);
+    });
+
     it('sets the renderIt and collapsed attribute on files', () => {
       const firstParallelDiffLine = preparedDiff.diff_files[0].parallel_diff_lines[2];