1 files changed, 35 insertions, 0 deletions
diff --git a/spec/frontend/vue_shared/components/source_viewer/utils_spec.js b/spec/frontend/vue_shared/components/source_viewer/utils_spec.js
new file mode 100644
index 00000000000..0ac72aa9afb
--- /dev/null
+++ b/spec/frontend/vue_shared/components/source_viewer/utils_spec.js
@@ -0,0 +1,35 @@
+import { setHTMLFixture } from 'helpers/fixtures';
+import {
+  calculateBlameOffset,
+  toggleBlameClasses,
+} from '~/vue_shared/components/source_viewer/utils';
+import { SOURCE_CODE_CONTENT_MOCK, BLAME_DATA_MOCK } from './mock_data';
+
+describe('SourceViewer utils', () => {
+  beforeEach(() => setHTMLFixture(SOURCE_CODE_CONTENT_MOCK));
+
+  const findContent = () => document.querySelector('.content');
+
+  describe('calculateBlameOffset', () => {
+    it('returns an offset of zero if line number === 1', () => {
+      expect(calculateBlameOffset(1)).toBe('0px');
+    });
+
+    it('calculates an offset for the blame component', () => {
+      const { offsetTop } = document.querySelector('#LC3');
+      expect(calculateBlameOffset(3)).toBe(`${offsetTop}px`);
+    });
+  });
+
+  describe('toggleBlameClasses', () => {
+    it('adds classes', () => {
+      toggleBlameClasses(BLAME_DATA_MOCK, true);
+      expect(findContent()).toMatchSnapshot();
+    });
+
+    it('removes classes', () => {
+      toggleBlameClasses(BLAME_DATA_MOCK, false);
+      expect(findContent()).toMatchSnapshot();
+    });
+  });
+});