Extract spawn logic into a wrapper and add tests

.jest/setEnvVars.ts

@@ -0,0 +1,5 @@
+/*
+This ensures that the PATH of the machine that the tests are running on,
+doesn't leak into our tests.
+*/
+process.env.PATH = '' 

jest.config.js

@@ -1,6 +1,7 @@
 module.exports = {
   clearMocks: true,
   moduleFileExtensions: ['js', 'ts'],
+  setupFiles: ["<rootDir>/.jest/setEnvVars.ts"],
   testEnvironment: 'node',
   testMatch: ['**/*.test.ts'],
   testRunner: 'jest-circus/runner',

src/__tests__/git.test.ts

@@ -0,0 +1,88 @@
+import * as fs from 'fs'
+import * as git from '../git'
+import * as spawn from '../spawn'
+import * as core from '@actions/core'
+
+// We want to mock only the rmSync method on the fs module, and leave everything
+// else untouched.
+jest.mock('fs', () => ({
+  ...jest.requireActual('fs'),
+  rmSync: jest.fn()
+}))
+
+describe('git', () => {
+  // We don't want to _actually_ spawn external commands, so we mock the function
+  let spawnSpy: jest.SpyInstance
+  // Capture the startGroup calls
+  let coreSpy: jest.SpyInstance
+  // The script calls fs.rmSync, so let's mock it and verify it was called
+  let rmSyncSpy: jest.SpyInstance
+
+  beforeEach(() => {
+    coreSpy = jest.spyOn(core, 'startGroup')
+    spawnSpy = jest.spyOn(spawn, 'spawnAndWaitForExitCode').mockResolvedValue({
+      // 0 is the exit code for success
+      exitCode: 0
+    })
+    // We don't want to _actually_ clone the repo, so we mock the function
+    jest.spyOn(git, 'clone').mockResolvedValue()
+    rmSyncSpy = fs.rmSync as jest.Mocked<typeof fs>['rmSync']
+  })
+
+  test('getViaGit build-installers x86_64', async () => {
+    const flavor = 'build-installers'
+    const architecture = 'x86_64'
+    const outputDirectory = 'outputDirectory'
+    const {artifactName, download} = await git.getViaGit(flavor, architecture)
+
+    expect(artifactName).toEqual('git-sdk-64-build-installers')
+
+    await download(outputDirectory, true)
+
+    expect(coreSpy).toHaveBeenCalledWith(`Creating ${flavor} artifact`)
+    expect(spawnSpy).toHaveBeenCalledWith(
+      expect.stringContaining('/bash.exe'),
+      expect.arrayContaining([
+        '.tmp/build-extra/please.sh',
+        'create-sdk-artifact',
+        `--architecture=${architecture}`,
+        `--out=${outputDirectory}`
+      ]),
+      expect.objectContaining({
+        env: expect.objectContaining({
+          // We want to ensure that the correct /bin folders are in the PATH,
+          // so that please.sh can find git.exe
+          // https://github.com/git-for-windows/setup-git-for-windows-sdk/issues/951
+          PATH:
+            expect.stringContaining('/clangarm64/bin') &&
+            expect.stringContaining('/mingw64/bin')
+        })
+      })
+    )
+    expect(rmSyncSpy).toHaveBeenCalledWith('.tmp', {recursive: true})
+  })
+
+  test('getViaGit full x86_64', async () => {
+    const flavor = 'full'
+    const architecture = 'x86_64'
+    const outputDirectory = 'outputDirectory'
+    const {artifactName, download} = await git.getViaGit(flavor, architecture)
+
+    expect(artifactName).toEqual('git-sdk-64-full')
+
+    await download(outputDirectory, true)
+
+    expect(coreSpy).toHaveBeenCalledWith(`Checking out git-sdk-64`)
+    expect(spawnSpy).toHaveBeenCalledWith(
+      expect.stringContaining('/git.exe'),
+      expect.arrayContaining([
+        '--git-dir=.tmp',
+        'worktree',
+        'add',
+        outputDirectory
+      ]),
+      expect.any(Object)
+    )
+    expect(rmSyncSpy).toHaveBeenCalledWith('.tmp', {recursive: true})
+  })
+})