fix watch mode (#482)

.github/workflows/main.yml

@@ -12,6 +12,23 @@ permissions:
     contents: read
 
 jobs:
+    check-tests-are-watchable:
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v3
+            - uses: actions/setup-node@v3
+              with:
+                  node-version: "lts/*"
+                  cache: npm
+            - name: Install dependencies
+              run: |
+                  npm ci
+              env:
+                  PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: 1
+            - name: Tests that tests are watchable
+              run: |
+                  ./scripts/test-watch-mode-works.sh
+
     prettier:
         runs-on: ubuntu-latest
         steps:

scripts/test-watch-mode-works.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+out=$(mktemp)
+# make silent background
+npx mocha --watch 2>>$out.err 1>>$out &
+
+PID=$!
+#echo pid of mocha: $PID
+
+echo "Round 1" >> out
+touch src/fake-timers-src.js
+sleep 3
+echo "Round 2" >> out
+touch src/fake-timers-src.js
+sleep 2
+echo "Cleanup" >> out
+
+# Kill the process manually
+kill $PID >/dev/null
+kill -9 $PID >/dev/null
+
+#cat $out.err
+if grep failing $out; then
+    echo "This means some tests do not clean up after themselves or otherwise do not work in Mocha's watch mode"
+    echo "See $out for details or run $0 yourself"
+    exit 1
+fi
+exit 0

test/fake-timers-test.js

@@ -21,7 +21,13 @@ const {
     utilPromisifyAvailable,
 } = require("./helpers/setup-tests");
 
-var timersModule;
+let timersModule;
+
+/* eslint-disable no-underscore-dangle */
+globalObject.__runs = globalObject.__runs || 0;
+
+const isRunningInWatchMode = ++globalObject.__runs > 1;
+/* eslint-enable no-underscore-dangle */
 
 if (typeof require === "function" && typeof module === "object") {
     try {
@@ -3582,6 +3588,9 @@ describe("FakeTimers", function () {
                     return this.skip();
                 }
 
+                const backupDescriptors =
+                    Object.getOwnPropertyDescriptors(Performance);
+
                 function noop() {
                     return ["foo"];
                 }
@@ -3612,9 +3621,13 @@ describe("FakeTimers", function () {
                 assert.equals(performance.getEntriesByName(), ["foo"]);
                 assert.equals(performance.getEntriesByType(), ["foo"]);
 
-                delete Performance.prototype.getEntries;
-                delete Performance.prototype.getEntriesByName;
-                delete Performance.prototype.getEntriesByTime;
+                Object.keys(backupDescriptors).forEach((key) => {
+                    Object.defineProperty(
+                        Performance.prototype,
+                        key,
+                        backupDescriptors[key]
+                    );
+                });
             });
         }
 
@@ -3803,7 +3816,7 @@ describe("FakeTimers", function () {
             const origSetInterval = globalObject.setInterval;
             const origClearInterval = globalObject.clearInterval;
 
-            var clock = FakeTimers.install({
+            const clock = FakeTimers.install({
                 shouldAdvanceTime: true,
                 toFake: ["setTimeout"],
             });
@@ -3830,16 +3843,23 @@ describe("FakeTimers", function () {
         }
 
         afterEach(function () {
-            if (this.clock) {
+            if (this.clock?.uninstall) {
                 this.clock.uninstall();
             }
+            sinon.restore();
         });
 
         it("outputs a warning once if not enabled", function (done) {
+            // This test does not work well in watch mode, as Chokidar sets up timers
+            // that trips up this test
+            if (isRunningInWatchMode) {
+                this.skip();
+            }
+
             const timer = globalObject.setTimeout(createCallback(done, true));
             const stub = sinon.stub(globalObject.console, "warn");
-
             this.clock = FakeTimers.install();
+
             globalObject.clearTimeout(timer);
             globalObject.clearTimeout(timer);
             assert.equals(stub.callCount, 1);
@@ -4826,6 +4846,7 @@ describe("loop limit stack trace", function () {
             function recursiveQueueMicroTask() {
                 test.clock.queueMicrotask(recursiveQueueMicroTask);
             }
+
             recursiveQueueMicroTask();
         });
 
@@ -4853,6 +4874,7 @@ describe("loop limit stack trace", function () {
             function recursiveQueueMicroTask() {
                 test.clock.nextTick(recursiveQueueMicroTask);
             }
+
             recursiveQueueMicroTask();
         });
 
@@ -4882,6 +4904,7 @@ describe("loop limit stack trace", function () {
                     recursiveCreateTimer();
                 }, 10);
             }
+
             recursiveCreateTimer();
         });
 
@@ -4933,6 +4956,7 @@ describe("loop limit stack trace", function () {
                     10
                 );
             }
+
             recursiveCreateTimer();
         });
 
@@ -4981,6 +5005,7 @@ describe("loop limit stack trace", function () {
                     recursiveCreateTimer();
                 }, 10);
             }
+
             recursiveCreateTimer();
         });
 
@@ -5035,6 +5060,7 @@ describe("loop limit stack trace", function () {
                     recursiveCreateTimer();
                 });
             }
+
             recursiveCreateTimer();
         });
 
@@ -5085,6 +5111,7 @@ describe("loop limit stack trace", function () {
                     }
                 );
             }
+
             recursiveCreateTimer();
         });