fix(mocha): fail fast when test hook import chain rejects

In 4.x the per-test setup()/teardown() hooks load ./test.js via a dynamic
import() with no .catch(). If that import rejects, or the .then body throws
(e.g. enhanceMochaTest on an undefined test, a listener throwing), done() is
never called and the mocha hook hangs forever — the silent-hang failure mode
the 4.0 release is most concerned with.

This mirrors the existing suiteSetup()/suiteTeardown() shape exactly: append a
.catch(err => doneFn(err)) to both import chains. No recorder.errHandler is
added (the per-test handler owns the single errFn slot). makeDoneCallableOnce
already guards against a double done() call.

Adds 3 regression tests: setup() and teardown() with a throwing then-body call
done with the error within 1s instead of hanging, plus a happy-path check.
Reverting the fix makes the two error-path tests hang (verified).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
(cherry picked from commit ac59a40)

Author: DavertMik

lib/mocha/asyncWrapper.js

@@ -197,23 +197,31 @@ export function setup(suite) {
   return function (done) {
     const doneFn = makeDoneCallableOnce(done)
     recorder.startUnlessRunning()
-    import('./test.js').then(testModule => {
-      const { enhanceMochaTest } = testModule.default || testModule
-      event.emit(event.test.before, enhanceMochaTest(suite?.ctx?.currentTest ?? suite?.currentTest))
-      recorder.add(() => doneFn())
-    })
+    import('./test.js')
+      .then(testModule => {
+        const { enhanceMochaTest } = testModule.default || testModule
+        event.emit(event.test.before, enhanceMochaTest(suite?.ctx?.currentTest ?? suite?.currentTest))
+        recorder.add(() => doneFn())
+      })
+      .catch(err => {
+        doneFn(err)
+      })
   }
 }
 
 export function teardown(suite) {
   return function (done) {
     const doneFn = makeDoneCallableOnce(done)
     recorder.startUnlessRunning()
-    import('./test.js').then(testModule => {
-      const { enhanceMochaTest } = testModule.default || testModule
-      event.emit(event.test.after, enhanceMochaTest(suite?.ctx?.currentTest ?? suite?.currentTest))
-      recorder.add(() => doneFn())
-    })
+    import('./test.js')
+      .then(testModule => {
+        const { enhanceMochaTest } = testModule.default || testModule
+        event.emit(event.test.after, enhanceMochaTest(suite?.ctx?.currentTest ?? suite?.currentTest))
+        recorder.add(() => doneFn())
+      })
+      .catch(err => {
+        doneFn(err)
+      })
   }
 }
 

test/unit/mocha/asyncWrapper_test.js

@@ -230,4 +230,43 @@ describe('AsyncWrapper', () => {
       expect(suiteTests[0].err, 'the suite test got the hook error attached').to.be.instanceof(Error)
     })
   })
+
+  describe('setup/teardown import hardening (regression)', () => {
+    beforeEach(() => recorder.start())
+
+    it('setup(): a throwing then-body calls done with the error instead of hanging', async () => {
+      const suite = {
+        ctx: {
+          get currentTest() {
+            throw new Error('setup-boom')
+          },
+        },
+      }
+      const { count, arg } = await runHook(setup(suite), 1000)
+      expect(count).to.equal(1)
+      expect(arg).to.be.instanceof(Error)
+      expect(arg.message).to.equal('setup-boom')
+    })
+
+    it('teardown(): a throwing then-body calls done with the error instead of hanging', async () => {
+      const suite = {
+        ctx: {
+          get currentTest() {
+            throw new Error('teardown-boom')
+          },
+        },
+      }
+      const { count, arg } = await runHook(teardown(suite), 1000)
+      expect(count).to.equal(1)
+      expect(arg).to.be.instanceof(Error)
+      expect(arg.message).to.equal('teardown-boom')
+    })
+
+    it('setup(): happy path calls done with no error', async () => {
+      const suite = { ctx: { currentTest: { title: 'a sample test' } } }
+      const { count, arg } = await runHook(setup(suite), 1000)
+      expect(count).to.equal(1)
+      expect(arg, 'done called with no error').to.be.undefined
+    })
+  })
 })