Add unit tests for initArkoseLabsScript

ee/spec/frontend/arkose_labs/init_arkose_labs_script_spec.js

+import { initArkoseLabsScript } from 'ee/arkose_labs/init_arkose_labs_script';
+
+jest.mock('lodash/uniqueId', () => () => 'initArkoseLabsScript_callback');
+
+describe('initArkoseLabsScript', () => {
+  let subject;
+
+  const initSubject = () => {
+    subject = initArkoseLabsScript({ publicKey: 'arkose-labs-public-api-key' });
+  };
+
+  const findScriptTags = () => document.querySelectorAll('script');
+
+  afterEach(() => {
+    subject = null;
+    document.getElementsByTagName('html')[0].innerHTML = '';
+  });
+
+  it('sets a global enforcement callback', () => {
+    initSubject();
+
+    expect(window.initArkoseLabsScript_callback).not.toBe(undefined);
+  });
+
+  it('adds ArkoseLabs scripts to the HTML head', () => {
+    expect(findScriptTags()).toHaveLength(0);
+
+    initSubject();
+
+    expect(findScriptTags()).toHaveLength(1);
+  });
+
+  it('when callback is called, cleans up the global object and resolves the Promise', () => {
+    initSubject();
+    const enforcement = 'ArkoseLabsEnforcement';
+    window.initArkoseLabsScript_callback(enforcement);
+
+    expect(window.initArkoseLabsScript_callback).toBe(undefined);
+    return expect(subject).resolves.toBe(enforcement);
+  });
+});