Update example tests

__tests__/index.test.ts

@@ -1,15 +1,80 @@
-import { wait } from '../src/wait'
-import { expect, test } from '@jest/globals'
+/**
+ * Unit tests for the action's entrypoint, src/index.ts
+ *
+ * These should be run as if the action was called from a workflow.
+ * Specifically, the inputs listed in `action.yml` should be set as environment
+ * variables following the pattern `INPUT_<INPUT_NAME>`.
+ */
 
-test('throws invalid number', async () => {
-  const input = parseInt('foo', 10)
-  await expect(wait(input)).rejects.toThrow('milliseconds not a number')
-})
+import * as core from '@actions/core'
+import * as index from '../src/index'
 
-test('wait 500 ms', async () => {
-  const start = new Date()
-  await wait(500)
-  const end = new Date()
-  const delta = Math.abs(end.getTime() - start.getTime())
-  expect(delta).toBeGreaterThan(450)
+// Mock the GitHub Actions core library
+const debugMock = jest.spyOn(core, 'debug')
+const getInputMock = jest.spyOn(core, 'getInput')
+const setFailedMock = jest.spyOn(core, 'setFailed')
+const setOutputMock = jest.spyOn(core, 'setOutput')
+
+// Mock the action's entrypoint
+const runMock = jest.spyOn(index, 'run')
+
+// Other utilities
+const timeRegex = /^\d{2}:\d{2}:\d{2}/
+
+describe('action', () => {
+  beforeEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it('sets the time output', async () => {
+    // Set the action's inputs as return values from core.getInput()
+    getInputMock.mockImplementation((name: string): string => {
+      switch (name) {
+        case 'milliseconds':
+          return '500'
+        default:
+          return ''
+      }
+    })
+
+    await index.run()
+    expect(runMock).toHaveReturned()
+
+    // Verify that all of the core library functions were called correctly
+    expect(debugMock).toHaveBeenNthCalledWith(1, 'Waiting 500 milliseconds ...')
+    expect(debugMock).toHaveBeenNthCalledWith(
+      2,
+      expect.stringMatching(timeRegex)
+    )
+    expect(debugMock).toHaveBeenNthCalledWith(
+      3,
+      expect.stringMatching(timeRegex)
+    )
+    expect(setOutputMock).toHaveBeenNthCalledWith(
+      1,
+      'time',
+      expect.stringMatching(timeRegex)
+    )
+  })
+
+  it('sets a failed status', async () => {
+    // Set the action's inputs as return values from core.getInput()
+    getInputMock.mockImplementation((name: string): string => {
+      switch (name) {
+        case 'milliseconds':
+          return 'this is not a number'
+        default:
+          return ''
+      }
+    })
+
+    await index.run()
+    expect(runMock).toHaveReturned()
+
+    // Verify that all of the core library functions were called correctly
+    expect(setFailedMock).toHaveBeenNthCalledWith(
+      1,
+      'milliseconds not a number'
+    )
+  })
 })

__tests__/wait.test.ts

@@ -0,0 +1,25 @@
+/**
+ * Unit tests for src/wait.ts
+ */
+
+import { wait } from '../src/wait'
+import { expect } from '@jest/globals'
+
+describe('wait.ts', () => {
+  it('throws an invalid number', async () => {
+    const input = parseInt('foo', 10)
+    expect(isNaN(input)).toBe(true)
+
+    await expect(wait(input)).rejects.toThrow('milliseconds not a number')
+  })
+
+  it('waits with a valid number', async () => {
+    const start = new Date()
+    await wait(500)
+    const end = new Date()
+
+    const delta = Math.abs(end.getTime() - start.getTime())
+
+    expect(delta).toBeGreaterThan(450)
+  })
+})