test(waitFor): Add current behavior for legacy fake timers and requestAnimationFrame (#978)

eps1lon · web-flow · commit f78d2894c86e · 2021-06-20T09:49:23.000+02:00
diff --git a/src/__tests__/fake-timers.js b/src/__tests__/fake-timers.js
@@ -79,3 +79,43 @@ test('recursive timers do not cause issues', async () => {
 
   recurse = false
 })
+
+// TODO: Should fail i.e. work the same as with "modern fake timers" once https://github.com/facebook/jest/pull/11567 is released.
+test('legacy fake timers do not waitFor requestAnimationFrame', async () => {
+  jest.useFakeTimers('legacy')
+
+  let exited = false
+  requestAnimationFrame(() => {
+    exited = true
+  })
+
+  await expect(async () => {
+    await waitFor(() => {
+      expect(exited).toBe(true)
+    })
+  }).rejects.toThrowErrorMatchingInlineSnapshot(`
+          "expect(received).toBe(expected) // Object.is equality
+
+          Expected: true
+          Received: false
+
+          Ignored nodes: comments, <script />, <style />
+          <html>
+            <head />
+            <body />
+          </html>"
+        `)
+})
+
+test('modern fake timers do waitFor requestAnimationFrame', async () => {
+  jest.useFakeTimers('modern')
+
+  let exited = false
+  requestAnimationFrame(() => {
+    exited = true
+  })
+
+  await waitFor(() => {
+    expect(exited).toBe(true)
+  })
+})
