From 7dc493a321c56994a5376f76366e6eea62abd0aa Mon Sep 17 00:00:00 2001
From: Rob Young <rob@robyoung.digital>
Date: Mon, 22 Feb 2021 11:02:45 +0000
Subject: [PATCH] Run script in GITHUB_WORKSPACE directory

Change to the GITHUB_WORKSPACE directory before running the script so
that callers do not have to exlicitly use the GITHUB_WORKSPACE
environment variable when requiring script files.

Workflow run steps are run within the GITHUB_WORKSPACE so this seems
like the expected default.
---
 README.md                       |  5 ++--
 __test__/async-function.test.ts | 44 +++++++++++++++++++++++++++++++++
 dist/index.js                   | 15 +++++++++--
 src/async-function.ts           | 15 +++++++++--
 4 files changed, 73 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 98b4ed6..723749f 100644
--- a/README.md
+++ b/README.md
@@ -243,11 +243,12 @@ jobs:
       - uses: actions/github-script@v3
         with:
           script: |
-            const script = require(`${process.env.GITHUB_WORKSPACE}/path/to/script.js`)
+            const script = require(`./path/to/script.js`)
             console.log(script({github, context}))
 ```
 
-_Note that the script path given to `require()` must be an **absolute path** in this case, hence using [`GITHUB_WORKSPACE`](https://docs.github.com/en/actions/configuring-and-managing-workflows/using-environment-variables#default-environment-variables)._
+The script will be run within the [`GITHUB_WORKSPACE`](https://docs.github.com/en/actions/configuring-and-managing-workflows/using-environment-variables#default-environment-variables)
+directory.
 
 And then export a function from your module:
 
diff --git a/__test__/async-function.test.ts b/__test__/async-function.test.ts
index d68b302..53e607d 100644
--- a/__test__/async-function.test.ts
+++ b/__test__/async-function.test.ts
@@ -25,4 +25,48 @@ describe('callAsyncFunction', () => {
   test('can access console', async () => {
     await callAsyncFunction({} as any, 'console')
   })
+
+  describe('change directory', () => {
+    const MOCK_CWD = '/path/to/action'
+    const MOCK_GITHUB_WORKSPACE = '/path/to/code'
+    const PREV_GITHUB_WORKSPACE = process.env.GITHUB_WORKSPACE
+
+    let chdir: jest.SpyInstance
+
+    beforeEach(() => {
+      jest.resetModules()
+      jest.clearAllMocks()
+
+      let cwd = MOCK_CWD
+
+      chdir = jest.spyOn(process, 'chdir').mockImplementation(directory => {
+        cwd = directory
+      })
+      jest.spyOn(process, 'cwd').mockImplementation(() => {
+        return cwd
+      })
+    })
+
+    afterAll(() => {
+      process.env.GITHUB_WORKSPACE = PREV_GITHUB_WORKSPACE
+    })
+
+    test('changes to GITHUB_WORKSPACE if environment variable is set', async () => {
+      process.env.GITHUB_WORKSPACE = MOCK_GITHUB_WORKSPACE
+
+      await callAsyncFunction({} as any, 'process')
+
+      expect(chdir.mock.calls.length).toBe(2)
+      expect(chdir.mock.calls[0][0]).toBe(MOCK_GITHUB_WORKSPACE)
+      expect(chdir.mock.calls[1][0]).toBe(MOCK_CWD)
+    })
+
+    test('does not change directory if GITHUB_WORKSPACE is not set', async () => {
+      delete process.env.GITHUB_WORKSPACE
+
+      await callAsyncFunction({} as any, 'process')
+
+      expect(chdir.mock.calls.length).toBe(0)
+    })
+  })
 })
diff --git a/dist/index.js b/dist/index.js
index 096668f..a8e4ce1 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -6117,8 +6117,19 @@ var io = __webpack_require__(436);
 // CONCATENATED MODULE: ./src/async-function.ts
 const AsyncFunction = Object.getPrototypeOf(async () => null).constructor;
 function callAsyncFunction(args, source) {
-    const fn = new AsyncFunction(...Object.keys(args), source);
-    return fn(...Object.values(args));
+    const previousWorkingDirectory = process.cwd();
+    try {
+        if (process.env.GITHUB_WORKSPACE !== undefined) {
+            process.chdir(process.env.GITHUB_WORKSPACE);
+        }
+        const fn = new AsyncFunction(...Object.keys(args), source);
+        return fn(...Object.values(args));
+    }
+    finally {
+        if (previousWorkingDirectory !== process.cwd()) {
+            process.chdir(previousWorkingDirectory);
+        }
+    }
 }
 
 // CONCATENATED MODULE: ./src/main.ts
diff --git a/src/async-function.ts b/src/async-function.ts
index 64d12ab..6305b70 100644
--- a/src/async-function.ts
+++ b/src/async-function.ts
@@ -19,6 +19,17 @@ export function callAsyncFunction<T>(
   args: AsyncFunctionArguments,
   source: string
 ): Promise<T> {
-  const fn = new AsyncFunction(...Object.keys(args), source)
-  return fn(...Object.values(args))
+  const previousWorkingDirectory = process.cwd()
+  try {
+    if (process.env.GITHUB_WORKSPACE !== undefined) {
+      process.chdir(process.env.GITHUB_WORKSPACE)
+    }
+
+    const fn = new AsyncFunction(...Object.keys(args), source)
+    return fn(...Object.values(args))
+  } finally {
+    if (previousWorkingDirectory !== process.cwd()) {
+      process.chdir(previousWorkingDirectory)
+    }
+  }
 }