test: add --exit flag to test:functional so mocha exits on Ubuntu

On Ubuntu CI, mocha completes the suite (142 passing) but never exits,
hanging build-and-check until GitHub cancels the job. The lingering
handle doesn't reproduce on macOS/Windows or darwin locally, and
process._getActiveHandles() reports nothing once tests finish. Adding
--exit force-terminates the runner after the suite completes, which
is safe because mocha already reported success.

Also makes the serialize-uploads preview test deterministic by gating
the stubbed upload on a test-controlled resolver rather than asserting
upload counts against real chokidar fs events.

Author: luis-almeida

package.json

@@ -52,7 +52,7 @@
     "link:bin": "bash ./scripts/link_dev.sh",
     "lint": "eslint . --ext .ts --config .eslintrc",
     "test": "nyc --extension .ts mocha --config=.mocharc.json --forbid-only 'packages/**/src/**/*.test.ts'",
-    "test:functional": "mocha --config=.mocharc.json -r ts-node/register 'packages/**/tests/**/*.test.ts'",
+    "test:functional": "mocha --config=.mocharc.json --exit -r ts-node/register 'packages/**/tests/**/*.test.ts'",
     "changelog": "lerna-changelog",
     "type:check": "lerna run type:check"
   },

packages/zcli-themes/tests/functional/preview.test.ts

@@ -134,20 +134,35 @@ describe('themes:preview', function () {
     preview
       .it('should serialize rapid successive changes instead of uploading concurrently', async () => {
         await waitForWatcherReady()
+        // Gate each upload on a test-controlled resolver so assertions don't
+        // depend on how the OS's chokidar backend coalesces fs events.
+        const pendingResolvers: Array<() => void> = []
+        fetchStub.withArgs(sinon.match({
+          url: 'https://z3ntest.zendesk.com/hc/api/internal/theming/local_preview',
+          method: 'PUT'
+        })).callsFake(() => new Promise(resolve => {
+          pendingResolvers.push(() => resolve({
+            status: 200,
+            ok: true,
+            text: () => Promise.resolve('')
+          }))
+        }))
         const initialCalls = previewUploadCalls()
         const partialsDir = path.join(baseThemePath, 'templates/partials')
         fs.mkdirSync(partialsDir, { recursive: true })
         const paths = ['a.hbs', 'b.hbs', 'c.hbs'].map(name => path.join(partialsDir, name))
         try {
           for (const p of paths) fs.writeFileSync(p, '<div/>')
           await waitForUploadCount(initialCalls + 1)
-          // Let any queued rerun finish; a working serializer produces at
-          // most one in-flight upload plus one queued rerun.
-          await new Promise(resolve => setTimeout(resolve, 500))
-          const calls = previewUploadCalls() - initialCalls
-          expect(calls).to.be.greaterThan(0)
-          expect(calls).to.be.at.most(2)
+          expect(previewUploadCalls() - initialCalls).to.eq(1)
+          pendingResolvers.shift()?.()
+          await waitForUploadCount(initialCalls + 2)
+          pendingResolvers.shift()?.()
+          await new Promise(resolve => setTimeout(resolve, 100))
+          expect(previewUploadCalls() - initialCalls).to.eq(2)
         } finally {
+          // Drain pending uploads so server.close() in afterEach isn't blocked.
+          pendingResolvers.forEach(fn => fn())
           fs.rmSync(partialsDir, { recursive: true, force: true })
         }
       })