test_runner: recalculate run duration on watch restart

PR-URL: #57786
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

Author: pmarchini

lib/internal/test_runner/runner.js

@@ -503,7 +503,10 @@ function watchFiles(testFiles, opts) {
 return;// Avoid rerunning files when file deleted
 }
 }
-
+// Reset the root start time to recalculate the duration
+// of the run
+opts.root.clearExecutionTime();
+// Restart test files
 if(opts.isolation==='none'){
 PromisePrototypeThen(restartTestFile(kIsolatedProcessName),undefined,(error)=>{
 triggerUncaughtException(error,true/* fromPromise */);

lib/internal/test_runner/test.js

@@ -1341,6 +1341,11 @@ class Test extends AsyncResource {
 this.parent.reportStarted();
 this.reporter.start(this.nesting,this.loc,this.name);
 }
+
+clearExecutionTime(){
+this.startTime=hrtime();
+this.endTime=null;
+}
 }
 
 classTestHookextendsTest{

test/parallel/test-runner-run-watch.mjs

@@ -189,6 +189,8 @@ async function testWatch(
 action==='rename2'&&awaittestRename();
 action==='delete'&&awaittestDelete();
 action==='create'&&awaittestCreate();
+
+returnruns;
 }
 
 describe('test runner watch mode',()=>{
@@ -241,6 +243,20 @@ describe('test runner watch mode', () => {
 awaittestWatch({action: 'create',fileToCreate: 'new-test-file.test.js'});
 });
 
+// This test is flaky by its nature as it relies on the timing of 2 different runs
+// considering the number of digits in the duration_ms is 9
+// the chances of having the same duration_ms are very low
+// but not impossible
+// In case of costant failures, consider increasing the number of tests
+it('should recalculate the run duration on a watch restart',async()=>{
+consttestRuns=awaittestWatch({file: 'test.js',fileToUpdate: 'test.js'});
+constdurations=testRuns.map((run)=>{
+construnDuration=run.match(/#duration_ms\s([\d.]+)/);
+returnrunDuration;
+});
+assert.notDeepStrictEqual(durations[0][1],durations[1][1]);
+});
+
 describe('test runner watch mode with different cwd',()=>{
 it(
 'should execute run using a different cwd for the runner than the process cwd',