1 files changed, 49 insertions, 21 deletions
diff --git a/spec/frontend/vue_shared/components/source_viewer/highlight_util_spec.js b/spec/frontend/vue_shared/components/source_viewer/highlight_util_spec.js
index 4a995e2fde1..d2dd4afe09e 100644
--- a/spec/frontend/vue_shared/components/source_viewer/highlight_util_spec.js
+++ b/spec/frontend/vue_shared/components/source_viewer/highlight_util_spec.js
@@ -1,15 +1,10 @@
-import hljs from 'highlight.js/lib/core';
-import languageLoader from '~/content_editor/services/highlight_js_language_loader';
+import hljs from 'highlight.js';
 import { registerPlugins } from '~/vue_shared/components/source_viewer/plugins/index';
 import { highlight } from '~/vue_shared/components/source_viewer/workers/highlight_utils';
+import { LINES_PER_CHUNK, NEWLINE } from '~/vue_shared/components/source_viewer/constants';
 
-jest.mock('highlight.js/lib/core', () => ({
-  highlight: jest.fn().mockReturnValue({}),
-  registerLanguage: jest.fn(),
-}));
-
-jest.mock('~/content_editor/services/highlight_js_language_loader', () => ({
-  javascript: jest.fn().mockReturnValue({ default: jest.fn() }),
+jest.mock('highlight.js', () => ({
+  highlight: jest.fn().mockReturnValue({ value: 'highlighted content' }),
 }));
 
 jest.mock('~/vue_shared/components/source_viewer/plugins/index', () => ({
@@ -17,28 +12,61 @@ jest.mock('~/vue_shared/components/source_viewer/plugins/index', () => ({
 }));
 
 const fileType = 'text';
-const content = 'function test() { return true };';
+const rawContent = 'function test() { return true }; \n // newline';
+const highlightedContent = 'highlighted content';
 const language = 'javascript';
 
 describe('Highlight utility', () => {
-  beforeEach(() => highlight(fileType, content, language));
-
-  it('loads the language', () => {
-    expect(languageLoader.javascript).toHaveBeenCalled();
-  });
+  beforeEach(() => highlight(fileType, rawContent, language));
 
   it('registers the plugins', () => {
     expect(registerPlugins).toHaveBeenCalled();
   });
 
-  it('registers the language', () => {
-    expect(hljs.registerLanguage).toHaveBeenCalledWith(
-      language,
-      languageLoader[language]().default,
+  it('highlights the content', () => {
+    expect(hljs.highlight).toHaveBeenCalledWith(rawContent, { language });
+  });
+
+  it('splits the content into chunks', () => {
+    const contentArray = Array.from({ length: 140 }, () => 'newline'); // simulate 140 lines of code
+
+    const chunks = [
+      {
+        language,
+        highlightedContent,
+        rawContent: contentArray.slice(0, 70).join(NEWLINE), // first 70 lines
+        startingFrom: 0,
+        totalLines: LINES_PER_CHUNK,
+      },
+      {
+        language,
+        highlightedContent: '',
+        rawContent: contentArray.slice(70, 140).join(NEWLINE), // last 70 lines
+        startingFrom: 70,
+        totalLines: LINES_PER_CHUNK,
+      },
+    ];
+
+    expect(highlight(fileType, contentArray.join(NEWLINE), language)).toEqual(
+      expect.arrayContaining(chunks),
     );
   });
+});
 
-  it('highlights the content', () => {
-    expect(hljs.highlight).toHaveBeenCalledWith(content, { language });
+describe('unsupported languages', () => {
+  const unsupportedLanguage = 'some_unsupported_language';
+
+  beforeEach(() => highlight(fileType, rawContent, unsupportedLanguage));
+
+  it('does not register plugins', () => {
+    expect(registerPlugins).not.toHaveBeenCalled();
+  });
+
+  it('does not attempt to highlight the content', () => {
+    expect(hljs.highlight).not.toHaveBeenCalled();
+  });
+
+  it('does not return a result', () => {
+    expect(highlight(fileType, rawContent, unsupportedLanguage)).toBe(undefined);
   });
 });