1 files changed, 47 insertions, 0 deletions
diff --git a/spec/frontend/create_cluster/gke_cluster/gapi_loader_spec.js b/spec/frontend/create_cluster/gke_cluster/gapi_loader_spec.js
new file mode 100644
index 00000000000..9e4d6996340
--- /dev/null
+++ b/spec/frontend/create_cluster/gke_cluster/gapi_loader_spec.js
@@ -0,0 +1,47 @@
+import gapiLoader from '~/create_cluster/gke_cluster/gapi_loader';
+
+describe('gapiLoader', () => {
+  // A mock for document.head.appendChild to intercept the script tag injection.
+  let mockDOMHeadAppendChild;
+
+  beforeEach(() => {
+    mockDOMHeadAppendChild = jest.spyOn(document.head, 'appendChild');
+  });
+
+  afterEach(() => {
+    mockDOMHeadAppendChild.mockRestore();
+    delete window.gapi;
+    delete window.gapiPromise;
+    delete window.onGapiLoad;
+  });
+
+  it('returns a promise', () => {
+    expect(gapiLoader()).toBeInstanceOf(Promise);
+  });
+
+  it('returns the same promise when already loading', () => {
+    const first = gapiLoader();
+    const second = gapiLoader();
+    expect(first).toBe(second);
+  });
+
+  it('resolves the promise when the script loads correctly', async () => {
+    mockDOMHeadAppendChild.mockImplementationOnce((script) => {
+      script.removeAttribute('src');
+      script.appendChild(
+        document.createTextNode(`window.gapi = 'hello gapi'; window.onGapiLoad()`),
+      );
+      document.head.appendChild(script);
+    });
+    await expect(gapiLoader()).resolves.toBe('hello gapi');
+    expect(mockDOMHeadAppendChild).toHaveBeenCalled();
+  });
+
+  it('rejects the promise when the script fails loading', async () => {
+    mockDOMHeadAppendChild.mockImplementationOnce((script) => {
+      script.onerror(new Error('hello error'));
+    });
+    await expect(gapiLoader()).rejects.toThrow('hello error');
+    expect(mockDOMHeadAppendChild).toHaveBeenCalled();
+  });
+});