stabilize watch helper using run-completion sync

Author: mostafaNazari702

test/integration/helpers.js

@@ -432,32 +432,92 @@ async function runMochaWatchAsync(args, opts, change) {
   }
   opts = {
     sleepMs: 2000,
+    expectedRuns: 2,
     stdio: ["pipe", "pipe", "inherit"],
     ...opts,
     fork: process.platform === "win32",
   };
+  const { sleepMs, expectedRuns } = opts;
+  const isJSON = args.some(
+    (arg, i) =>
+      arg === "--reporter=json" ||
+      (arg === "--reporter" && args[i + 1] === "json"),
+  );
+
   const [mochaProcess, resultPromise] = invokeMochaAsync(
     [...args, "--watch"],
     opts,
   );
-  await sleep(opts.sleepMs);
-  await change(mochaProcess);
-  await sleep(opts.sleepMs);
 
-  if (
-    !(mochaProcess.connected
-      ? mochaProcess.send("SIGINT")
-      : mochaProcess.kill("SIGINT"))
-  ) {
-    throw new Error("failed to send signal to subprocess");
-  }
+  const RUN_DONE_MARKER = '"stats":';
+  let buf = "";
+  let runsDone = 0;
+  let notifyProgress = null;
+
+  const onStdout = (data) => {
+    buf += data.toString();
+    let advanced = false;
+    let idx;
+    while ((idx = buf.indexOf(RUN_DONE_MARKER)) !== -1) {
+      runsDone += 1;
+      buf = buf.slice(idx + RUN_DONE_MARKER.length);
+      advanced = true;
+    }
+    if (advanced && notifyProgress) notifyProgress();
+  };
+
+  const waitForRuns = (target, timeoutMs) =>
+    new Promise((resolve) => {
+      if (runsDone >= target) return resolve(true);
+      const timer = setTimeout(() => {
+        notifyProgress = null;
+        debug("watch run wait timed out at %d/%d", runsDone, target);
+        resolve(false);
+      }, timeoutMs);
+      notifyProgress = () => {
+        if (runsDone >= target) {
+          clearTimeout(timer);
+          notifyProgress = null;
+          resolve(true);
+        }
+      };
+    });
 
-  const res = await resultPromise;
+  mochaProcess.stdout.on("data", onStdout);
 
-  // we kill the process with `SIGINT`, so it will always appear as "failed" to our
-  // custom assertions (a non-zero exit code 130). just change it to 0.
-  res.code = 0;
-  return res;
+  try {
+    if (isJSON) {
+      await waitForRuns(1, sleepMs * 3);
+    } else {
+      await sleep(sleepMs);
+    }
+
+    const baseline = runsDone;
+    await change(mochaProcess);
+
+    if (isJSON && expectedRuns > baseline) {
+      await waitForRuns(expectedRuns, sleepMs * 3);
+    } else {
+      await sleep(sleepMs);
+    }
+
+    if (
+      !(mochaProcess.connected
+        ? mochaProcess.send("SIGINT")
+        : mochaProcess.kill("SIGINT"))
+    ) {
+      throw new Error("failed to send signal to subprocess");
+    }
+
+    const res = await resultPromise;
+
+    // we kill the process with `SIGINT`, so it will always appear as "failed" to our
+    // custom assertions (a non-zero exit code 130). just change it to 0.
+    res.code = 0;
+    return res;
+  } finally {
+    mochaProcess.stdout.removeListener("data", onStdout);
+  }
 }
 
 /**

test/integration/options/watch.spec.js

@@ -53,9 +53,13 @@ describe("--watch", function () {
 
       replaceFileContents(testFile, "done();", "done((;");
 
-      return runMochaWatchJSONAsync([testFile], tempDir, () => {
-        replaceFileContents(testFile, "done((;", "done();");
-      }).then((results) => {
+      return runMochaWatchJSONAsync(
+        [testFile],
+        { cwd: tempDir, expectedRuns: 1 },
+        () => {
+          replaceFileContents(testFile, "done((;", "done();");
+        },
+      ).then((results) => {
         expect(results, "to have length", 1);
       });
     });
@@ -78,9 +82,13 @@ describe("--watch", function () {
 
         replaceFileContents(testFile, "done();", "done((;");
 
-        return runMochaWatchJSONAsync([testFile], tempDir, () => {
-          replaceFileContents(testFile, "done((;", "done();");
-        }).then((results) => {
+        return runMochaWatchJSONAsync(
+          [testFile],
+          { cwd: tempDir, expectedRuns: 1 },
+          () => {
+            replaceFileContents(testFile, "done((;", "done();");
+          },
+        ).then((results) => {
           expect(results, "to have length", 1);
         });
       });
@@ -131,7 +139,7 @@ describe("--watch", function () {
 
       return runMochaWatchJSONAsync(
         [testFile, "--watch-files", "lib"],
-        tempDir,
+        { cwd: tempDir, expectedRuns: 4 },
         async () => {
           fs.mkdirSync(libPath);
           await sleep(1000);
@@ -287,7 +295,7 @@ describe("--watch", function () {
 
       return runMochaWatchJSONAsync(
         [testFile, "--watch-files", "dir/*.xyz"],
-        tempDir,
+        { cwd: tempDir, expectedRuns: 1 },
         () => {
           touchFile(watchedFile);
         },
@@ -373,7 +381,7 @@ describe("--watch", function () {
 
       return runMochaWatchJSONAsync(
         [testFile, "--extension", "xyz,js"],
-        tempDir,
+        { cwd: tempDir, expectedRuns: 1 },
         () => {
           touchFile(gitFile);
           touchFile(nodeModulesFile);
@@ -398,7 +406,7 @@ describe("--watch", function () {
           "--watch-ignore",
           "dir/*ignore*",
         ],
-        tempDir,
+        { cwd: tempDir, expectedRuns: 1 },
         () => {
           touchFile(watchedFile);
         },
@@ -417,7 +425,7 @@ describe("--watch", function () {
 
       return runMochaWatchJSONAsync(
         [testFile, "--watch-files", "dir/[ab].js"],
-        tempDir,
+        { cwd: tempDir, expectedRuns: 1 },
         () => {
           touchFile(watchedFile);
         },