Assign unique name to sandbox directory (#171)

`withinSandbox` is designed for tests that need to act on the filesystem. It creates a temporary directory and passes it to the function so that it can do whatever it needs to do within the directory in a safer fashion. The name of the sandbox directory is generated from the current time to ensure that each one is unique. However, this causes problems when Jest is running more than one test file, each of which make use of the sandbox. Jest runs test files in parallel, so paired with the naming — and the fact that time can be frozen in tests — it is possible for two tests to create and use the same sandbox simultaneously. `withinSandbox` double-checks that the directory it would have created does not already exist, so when the first test creates the directory it will cause the second test to fail. Also, since `withinSandbox` removes the sandbox directory after it runs its function, this will also cause the second test to fail if it's still running and using that directory. To fix this, this commit changes `withinSandbox` to use a UUID to name the sandbox directory instead of the current time.
MetaMask · Mar 5, 2024 · de4b119 · de4b119
1 parent ec0237c
commit de4b119
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Showing 4 changed files with 56 additions and 21 deletions.
diff --git a/package.json b/package.json
@@ -59,7 +59,8 @@
     "debug": "^4.3.4",
     "pony-cause": "^2.1.10",
     "semver": "^7.5.4",
-    "superstruct": "^1.0.3"
+    "superstruct": "^1.0.3",
+    "uuid": "^9.0.1"
   },
   "devDependencies": {
     "@lavamoat/allow-scripts": "^2.3.1",
@@ -72,6 +73,7 @@
     "@types/jest": "^28.1.7",
     "@types/jest-when": "^3.5.3",
     "@types/node": "^17.0.23",
+    "@types/uuid": "^9.0.8",
     "@typescript-eslint/eslint-plugin": "^5.43.0",
     "@typescript-eslint/parser": "^5.43.0",
     "depcheck": "^1.4.7",

diff --git a/src/fs.test.ts b/src/fs.test.ts
@@ -3,6 +3,7 @@ import { when } from 'jest-when';
 import os from 'os';
 import path from 'path';
 import util from 'util';
+import * as uuid from 'uuid';
 
 import {
   createSandbox,
@@ -18,6 +19,16 @@ import {
 
 const { withinSandbox } = createSandbox('utils');
 
+// Clone the `uuid` module so that we can spy on its exports
+jest.mock('uuid', () => {
+  return {
+    // This is how to mock an ES-compatible module in Jest.
+    // eslint-disable-next-line @typescript-eslint/naming-convention
+    __esModule: true,
+    ...jest.requireActual('uuid'),
+  };
+});
+
 describe('fs', () => {
   describe('readFile', () => {
     it('reads the contents of the given file as a UTF-8-encoded string', async () => {
@@ -674,9 +685,14 @@ describe('fs', () => {
     });
 
     it('does not create the sandbox directory immediately', async () => {
+      jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
       createSandbox('utils-fs');
 
-      const sandboxDirectoryPath = path.join(os.tmpdir(), 'utils-fs');
+      const sandboxDirectoryPath = path.join(
+        os.tmpdir(),
+        'utils-fs',
+        'AAAA-AAAA-AAAA-AAAA',
+      );
 
       await expect(fs.promises.stat(sandboxDirectoryPath)).rejects.toThrow(
         'ENOENT',
@@ -686,49 +702,48 @@ describe('fs', () => {
     describe('withinSandbox', () => {
       it('creates the sandbox directory and keeps it around before its given function ends', async () => {
         expect.assertions(1);
-
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
-        const sandboxDirectoryPath = path.join(
-          os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
-        );
 
         await withinTestSandbox(async () => {
+          const sandboxDirectoryPath = path.join(
+            os.tmpdir(),
+            'utils-fs',
+            'AAAA-AAAA-AAAA-AAAA',
+          );
           expect(await fs.promises.stat(sandboxDirectoryPath)).toStrictEqual(
             expect.anything(),
           );
         });
       });
 
       it('removes the sandbox directory after its given function ends', async () => {
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
-        const sandboxDirectoryPath = path.join(
-          os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
-        );
 
         await withinTestSandbox(async () => {
           // do nothing
         });
 
+        const sandboxDirectoryPath = path.join(
+          os.tmpdir(),
+          'utils-fs',
+          'AAAA-AAAA-AAAA-AAAA',
+        );
         await expect(fs.promises.stat(sandboxDirectoryPath)).rejects.toThrow(
           'ENOENT',
         );
       });
 
       it('throws if the sandbox directory already exists', async () => {
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
+
         const sandboxDirectoryPath = path.join(
           os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
+          'utils-fs',
+          'AAAA-AAAA-AAAA-AAAA',
         );
-
         try {
           await fs.promises.mkdir(sandboxDirectoryPath);
 

diff --git a/src/fs.ts b/src/fs.ts
@@ -4,6 +4,7 @@
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
+import * as uuid from 'uuid';
 
 import { isErrorWithCode, wrapError } from './errors';
 import type { Json } from './json';
@@ -240,8 +241,7 @@ export async function forceRemove(entryPath: string): Promise<void> {
  * ```
  */
 export function createSandbox(projectName: string): FileSandbox {
-  const timestamp = new Date().getTime();
-  const directoryPath = path.join(os.tmpdir(), `${projectName}--${timestamp}`);
+  const directoryPath = path.join(os.tmpdir(), projectName, uuid.v4());
 
   return {
     directoryPath,

diff --git a/yarn.lock b/yarn.lock
@@ -1226,6 +1226,7 @@ __metadata:
     "@types/jest": ^28.1.7
     "@types/jest-when": ^3.5.3
     "@types/node": ^17.0.23
+    "@types/uuid": ^9.0.8
     "@typescript-eslint/eslint-plugin": ^5.43.0
     "@typescript-eslint/parser": ^5.43.0
     debug: ^4.3.4
@@ -1253,6 +1254,7 @@ __metadata:
     tsup: ^7.2.0
     typedoc: ^0.23.15
     typescript: ~4.8.4
+    uuid: ^9.0.1
   languageName: unknown
   linkType: soft
 
@@ -1694,6 +1696,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@types/uuid@npm:^9.0.8":
+  version: 9.0.8
+  resolution: "@types/uuid@npm:9.0.8"
+  checksum: b8c60b7ba8250356b5088302583d1704a4e1a13558d143c549c408bf8920535602ffc12394ede77f8a8083511b023704bc66d1345792714002bfa261b17c5275
+  languageName: node
+  linkType: hard
+
 "@types/yargs-parser@npm:*":
   version: 21.0.0
   resolution: "@types/yargs-parser@npm:21.0.0"
@@ -7673,6 +7682,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"uuid@npm:^9.0.1":
+  version: 9.0.1
+  resolution: "uuid@npm:9.0.1"
+  bin:
+    uuid: dist/bin/uuid
+  checksum: 39931f6da74e307f51c0fb463dc2462807531dc80760a9bff1e35af4316131b4fc3203d16da60ae33f07fdca5b56f3f1dd662da0c99fea9aaeab2004780cc5f4
+  languageName: node
+  linkType: hard
+
 "v8-compile-cache-lib@npm:^3.0.1":
   version: 3.0.1
   resolution: "v8-compile-cache-lib@npm:3.0.1"