1 files changed, 77 insertions, 1 deletions
diff --git a/spec/frontend/diffs/utils/diff_file_spec.js b/spec/frontend/diffs/utils/diff_file_spec.js
index c6cfdfced65..3223b6c2dab 100644
--- a/spec/frontend/diffs/utils/diff_file_spec.js
+++ b/spec/frontend/diffs/utils/diff_file_spec.js
@@ -1,4 +1,11 @@
-import { prepareRawDiffFile, getShortShaFromFile } from '~/diffs/utils/diff_file';
+import {
+  prepareRawDiffFile,
+  getShortShaFromFile,
+  stats,
+  isNotDiffable,
+} from '~/diffs/utils/diff_file';
+import { diffViewerModes } from '~/ide/constants';
+import mockDiffFile from '../mock_data/diff_file';
 
 function getDiffFiles() {
   const loadFull = 'namespace/project/-/merge_requests/12345/diff_for_path?file_identifier=abc';
@@ -154,4 +161,73 @@ describe('diff_file utilities', () => {
       expect(getShortShaFromFile({ content_sha: cs })).toBe(response);
     });
   });
+
+  describe('stats', () => {
+    const noFile = [
+      "returns empty stats when the file isn't provided",
+      undefined,
+      {
+        text: '',
+        percent: 0,
+        changed: 0,
+        classes: '',
+        sign: '',
+        valid: false,
+      },
+    ];
+    const validFile = [
+      'computes the correct stats from a file',
+      mockDiffFile,
+      {
+        changed: 1024,
+        percent: 100,
+        classes: 'gl-text-green-600',
+        sign: '+',
+        text: '+1.00 KiB (+100%)',
+        valid: true,
+      },
+    ];
+    const negativeChange = [
+      'computed the correct states from a file with a negative size change',
+      {
+        ...mockDiffFile,
+        new_size: 0,
+        old_size: 1024,
+      },
+      {
+        changed: -1024,
+        percent: -100,
+        classes: 'gl-text-red-500',
+        sign: '',
+        text: '-1.00 KiB (-100%)',
+        valid: true,
+      },
+    ];
+
+    it.each([noFile, validFile, negativeChange])('%s', (_, file, output) => {
+      expect(stats(file)).toEqual(output);
+    });
+  });
+
+  describe('isNotDiffable', () => {
+    it.each`
+      bool     | vw
+      ${true}  | ${diffViewerModes.not_diffable}
+      ${false} | ${diffViewerModes.text}
+      ${false} | ${diffViewerModes.image}
+    `('returns $bool when the viewer is $vw', ({ bool, vw }) => {
+      expect(isNotDiffable({ viewer: { name: vw } })).toBe(bool);
+    });
+
+    it.each`
+      file
+      ${undefined}
+      ${null}
+      ${{}}
+      ${{ viewer: undefined }}
+      ${{ viewer: null }}
+    `('reports `false` when the file is `$file`', ({ file }) => {
+      expect(isNotDiffable(file)).toBe(false);
+    });
+  });
 });