Add test for runPeriodically

Signed-off-by: Oliver Sand <oliver.sand@sda-se.com>
2021-07-06 18:57:32 +02:00
parent 03715ceaa4
commit 0466606d84
1 changed files with 80 additions and 0 deletions
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2020 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { runPeriodically } from './runPeriodically';
+
+jest.useFakeTimers();
+
+describe('runPeriodically', () => {
+  const flushPromises = () => new Promise(setImmediate);
+  const advanceTimersByTime = async (time: number) => {
+    jest.advanceTimersByTime(time);
+    // Advancing the time with jest doesn't run all promises, but only sync code
+    await flushPromises();
+  };
+
+  it('runs task initially', async () => {
+    const task = jest.fn(async () => {});
+    const cancel = runPeriodically(task, 1000);
+    expect(task).toHaveBeenCalledTimes(1);
+    cancel();
+  });
+
+  it('runs at requested interval', async () => {
+    const task = jest.fn(async () => {});
+    const cancel = runPeriodically(task, 1000);
+    await flushPromises();
+    await advanceTimersByTime(1000);
+    await advanceTimersByTime(1000);
+    expect(task).toHaveBeenCalledTimes(3);
+    cancel();
+  });
+
+  it('stops after being canceled', async () => {
+    const task = jest.fn(async () => {});
+    const cancel = runPeriodically(task, 1000);
+    await flushPromises();
+    cancel();
+    await advanceTimersByTime(1000);
+    await advanceTimersByTime(1000);
+    expect(task).toHaveBeenCalledTimes(1);
+  });
+
+  it('continues running after failures', async () => {
+    const task = jest.fn(async () => {
+      throw new Error();
+    });
+    const cancel = runPeriodically(task, 1000);
+    await flushPromises();
+    await advanceTimersByTime(1000);
+    await advanceTimersByTime(1000);
+    expect(task).toHaveBeenCalledTimes(3);
+    cancel();
+  });
+
+  it('waits till a long running task is completed', async () => {
+    const task = jest.fn(
+      () => new Promise(resolve => setTimeout(resolve, 10000)),
+    );
+    const cancel = runPeriodically(task, 1000);
+    await flushPromises();
+    await advanceTimersByTime(1000);
+    expect(task).toHaveBeenCalledTimes(1);
+    await advanceTimersByTime(9000);
+    await advanceTimersByTime(1000);
+    expect(task).toHaveBeenCalledTimes(2);
+    cancel();
+  });
+});