test: mocha fs sandbox tests

Author: jbedard

examples/macro/mocha.bzl

@@ -22,5 +22,7 @@ def mocha_test(name, srcs, args = [], data = [], env = {}, **kwargs):
             # to the location Bazel expects.
             "MOCHA_FILE": "$$XML_OUTPUT_FILE",
         }),
+        preserve_symlinks_main = False,
+        copy_data_to_bin = False,
         **kwargs
     )

examples/macro/test.js

@@ -1,4 +1,5 @@
 const assert = require('assert')
+const { dirname } = require('node:path')
 
 describe('mocha', () => {
     it('integrates with Bazel', () => {
@@ -8,4 +9,13 @@ describe('mocha', () => {
     it('is in bazel-out', () => {
         assert.match(__dirname, /bazel-out/)
     })
+
+    it('is sandboxed', () => {
+        assert.match(__dirname, /examples\/macro\/test_\/test\.runfiles/)
+        assert.match(
+            __filename,
+            /-sandbox\/\d+\/execroot\/_main\/bazel-out\/[^/]+\/bin\/examples\/macro\/test_\/test.runfiles\/_main\/examples\/macro\/test\.js/
+        )
+        assert.equal(__dirname, dirname(__filename))
+    })
 })