fix

lib/internal/test_runner/runner.js

@@ -13,6 +13,7 @@ const {
   SafeSet,
 } = primordials;
 
+const { Buffer } = require('buffer');
 const { spawn } = require('child_process');
 const { readdirSync, statSync } = require('fs');
 const console = require('internal/console/global');
@@ -103,15 +104,34 @@ function filterExecArgv(arg) {
 
 function getRunArgs({ path, inspectPort }) {
   const argv = ArrayPrototypeFilter(process.execArgv, filterExecArgv);
-  console.log(`Running test ${path}...`, { inspectPort, isUsingInspector: isUsingInspector() });
   if (isUsingInspector()) {
     ArrayPrototypePush(argv, `--inspect-port=${getInspectPort(inspectPort)}`);
   }
-  console.log(`Running test ${path}...`, { inspectPort, argv });
   ArrayPrototypePush(argv, path);
   return argv;
 }
 
+function makeStderrCallback(callback) {
+  if (!isUsingInspector()) {
+    return callback;
+  }
+  let buffer = Buffer.alloc(0);
+  return (data) => {
+    callback(data);
+    const newData = Buffer.concat([buffer, data]);
+    const str = newData.toString('utf8');
+    let lines = str.split(/\r?\n/);
+    if (str.endsWith('\n'))
+      buffer = Buffer.alloc(0);
+    else
+      buffer = Buffer.from(lines.pop(), 'utf8');
+    lines = lines.join('\n');
+    if (isInspectorMessage(lines)) {
+      process.stderr.write(lines);
+    }
+  };
+}
+
 function runTestFile(path, root, inspectPort) {
   const subtest = root.createSubtest(Test, path, async (t) => {
     const args = getRunArgs({ path, inspectPort });
@@ -126,13 +146,9 @@ function runTestFile(path, root, inspectPort) {
       err = error;
     });
 
-    child.stderr.on('data', (data) => {
-      console.log('[stderr]', { data: data.toString() });
-      if (isInspectorMessage(data.toString())) {
-        process.stderr.write(data);
-      }
+    child.stderr.on('data', makeStderrCallback((data) => {
       stderr += data;
-    });
+    }));
 
     const { 0: { 0: code, 1: signal }, 1: stdout } = await SafePromiseAll([
       once(child, 'exit', { signal: t.signal }),