Convert to ESM

__tests__/index.test.ts

@@ -1,17 +0,0 @@
-/**
- * Unit tests for the action's entrypoint, src/index.ts
- */
-
-import * as main from '../src/main'
-
-// Mock the action's entrypoint
-const runMock = jest.spyOn(main, 'run').mockImplementation()
-
-describe('index', () => {
-  it('calls run when imported', () => {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    require('../src/index')
-
-    expect(runMock).toHaveBeenCalled()
-  })
-})

__tests__/main.test.ts

@@ -1,89 +1,62 @@
 /**
  * Unit tests for the action's main functionality, src/main.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>`.
+ * To mock dependencies in ESM, you can create fixtures that export mock
+ * functions and objects. For example, the core module is mocked in this test,
+ * so that the actual '@actions/core' module is not imported.
  */
+import { jest } from '@jest/globals'
+import * as core from '../__fixtures__/core.js'
+import { wait } from '../__fixtures__/wait.js'
 
-import * as core from '@actions/core'
-import * as main from '../src/main'
+// Mocks should be declared before the module being tested is imported.
+jest.unstable_mockModule('@actions/core', () => core)
+jest.unstable_mockModule('../src/wait.js', () => ({ wait }))
 
-// Mock the action's main function
-const runMock = jest.spyOn(main, 'run')
+// The module being tested should be imported dynamically. This ensures that the
+// mocks are used in place of any actual dependencies.
+const { run } = await import('../src/main.js')
 
-// Other utilities
-const timeRegex = /^\d{2}:\d{2}:\d{2}/
-
-// Mock the GitHub Actions core library
-let debugMock: jest.SpiedFunction<typeof core.debug>
-let errorMock: jest.SpiedFunction<typeof core.error>
-let getInputMock: jest.SpiedFunction<typeof core.getInput>
-let setFailedMock: jest.SpiedFunction<typeof core.setFailed>
-let setOutputMock: jest.SpiedFunction<typeof core.setOutput>
-
-describe('action', () => {
+describe('main.ts', () => {
   beforeEach(() => {
-    jest.clearAllMocks()
+    // Set the action's inputs as return values from core.getInput().
+    core.getInput.mockImplementation(() => '500')
 
-    debugMock = jest.spyOn(core, 'debug').mockImplementation()
-    errorMock = jest.spyOn(core, 'error').mockImplementation()
-    getInputMock = jest.spyOn(core, 'getInput').mockImplementation()
-    setFailedMock = jest.spyOn(core, 'setFailed').mockImplementation()
-    setOutputMock = jest.spyOn(core, 'setOutput').mockImplementation()
+    // Mock the wait function so that it does not actually wait.
+    wait.mockImplementation(() => Promise.resolve('done!'))
   })
 
-  it('sets the time output', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation(name => {
-      switch (name) {
-        case 'milliseconds':
-          return '500'
-        default:
-          return ''
-      }
-    })
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
 
-    await main.run()
-    expect(runMock).toHaveReturned()
+  it('Sets the time output', async () => {
+    await run()
 
-    // 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(
+    // Verify the time output was set.
+    expect(core.setOutput).toHaveBeenNthCalledWith(
       1,
       'time',
-      expect.stringMatching(timeRegex)
+      // Simple regex to match a time string in the format HH:MM:SS.
+      expect.stringMatching(/^\d{2}:\d{2}:\d{2}/)
     )
-    expect(errorMock).not.toHaveBeenCalled()
   })
 
-  it('sets a failed status', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation(name => {
-      switch (name) {
-        case 'milliseconds':
-          return 'this is not a number'
-        default:
-          return ''
-      }
-    })
+  it('Sets a failed status', async () => {
+    // Clear the getInput mock and return an invalid value.
+    core.getInput.mockClear().mockReturnValueOnce('this is not a number')
 
-    await main.run()
-    expect(runMock).toHaveReturned()
+    // Clear the wait mock and return a rejected promise.
+    wait
+      .mockClear()
+      .mockRejectedValueOnce(new Error('milliseconds is not a number'))
 
-    // Verify that all of the core library functions were called correctly
-    expect(setFailedMock).toHaveBeenNthCalledWith(
+    await run()
+
+    // Verify that the action was marked as failed.
+    expect(core.setFailed).toHaveBeenNthCalledWith(
       1,
-      'milliseconds not a number'
+      'milliseconds is not a number'
     )
-    expect(errorMock).not.toHaveBeenCalled()
   })
 })

__tests__/wait.test.ts

@@ -1,19 +1,18 @@
 /**
  * Unit tests for src/wait.ts
  */
-
-import { wait } from '../src/wait'
-import { expect } from '@jest/globals'
+import { wait } from '../src/wait.js'
 
 describe('wait.ts', () => {
-  it('throws an invalid number', async () => {
+  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')
+    await expect(wait(input)).rejects.toThrow('milliseconds is not a number')
   })
 
-  it('waits with a valid number', async () => {
+  it('Waits with a valid number', async () => {
     const start = new Date()
     await wait(500)
     const end = new Date()