test_runner: add enqueue and dequeue events

doc/api/test.md

@@ -1461,6 +1461,16 @@ object, streaming a series of events representing the execution of the tests.
 
 Emitted when code coverage is enabled and all tests have completed.
 
+### Event: `'test:dequeue'`
+
+* `data` {Object}
+  * `file` {string|undefined} The path of the test file,
+    undefined if test is not ran through a file.
+  * `name` {string} The test name.
+  * `nesting` {number} The nesting level of the test.
+
+Emitted when a test is dequeued, right before it is executed.
+
 ### Event: `'test:diagnostic'`
 
 * `data` {Object}
@@ -1471,6 +1481,16 @@ Emitted when code coverage is enabled and all tests have completed.
 
 Emitted when [`context.diagnostic`][] is called.
 
+### Event: `'test:enqueue'`
+
+* `data` {Object}
+  * `file` {string|undefined} The path of the test file,
+    undefined if test is not ran through a file.
+  * `name` {string} The test name.
+  * `nesting` {number} The nesting level of the test.
+
+Emitted when a test is enqueued for execution.
+
 ### Event: `'test:fail'`
 
 * `data` {Object}
@@ -1520,7 +1540,9 @@ Emitted when all subtests have completed for a given test.
   * `name` {string} The test name.
   * `nesting` {number} The nesting level of the test.
 
-Emitted when a test starts.
+Emitted when a test starts reporting its own and its subtests status.
+This event is guaranteed to be emitted in the same order as the tests are
+defined.
 
 ### Event: `'test:stderr'`
 

lib/internal/test_runner/test.js

@@ -311,7 +311,9 @@ class Test extends AsyncResource {
   async processPendingSubtests() {
     while (this.pendingSubtests.length > 0 && this.hasConcurrency()) {
       const deferred = ArrayPrototypeShift(this.pendingSubtests);
-      await deferred.test.run();
+      const test = deferred.test;
+      this.reporter.dequeue(test.nesting, kFilename, test.name);
+      await test.run();
       deferred.resolve();
     }
   }
@@ -469,6 +471,7 @@ class Test extends AsyncResource {
     // If there is enough available concurrency to run the test now, then do
     // it. Otherwise, return a Promise to the caller and mark the test as
     // pending for later execution.
+    this.reporter.enqueue(this.nesting, kFilename, this.name);
     if (!this.parent.hasConcurrency()) {
       const deferred = createDeferredPromise();
 
@@ -477,6 +480,7 @@ class Test extends AsyncResource {
       return deferred.promise;
     }
 
+    this.reporter.dequeue(this.nesting, kFilename, this.name);
     return this.run();
   }
 

lib/internal/test_runner/tests_stream.js

@@ -49,6 +49,14 @@ class TestsStream extends Readable {
     return { __proto__: null, todo: reason ?? true };
   }
 
+  enqueue(nesting, file, name) {
+    this[kEmitMessage]('test:enqueue', { __proto__: null, nesting, file, name });
+  }
+
+  dequeue(nesting, file, name) {
+    this[kEmitMessage]('test:dequeue', { __proto__: null, nesting, file, name });
+  }
+
   start(nesting, file, name) {
     this[kEmitMessage]('test:start', { __proto__: null, nesting, file, name });
   }

test/parallel/test-runner-reporters.js

@@ -97,7 +97,7 @@ describe('node:test reporters', { concurrency: true }, () => {
                                testFile]);
       assert.strictEqual(child.stderr.toString(), '');
       const stdout = child.stdout.toString();
-      assert.match(stdout, /{"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/);
+      assert.match(stdout, /{"test:enqueue":5,"test:dequeue":5,"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/);
       assert.strictEqual(stdout.slice(0, filename.length + 2), `${filename} {`);
     });
   });
@@ -109,7 +109,7 @@ describe('node:test reporters', { concurrency: true }, () => {
     assert.strictEqual(child.stderr.toString(), '');
     assert.match(
       child.stdout.toString(),
-      /^package: reporter-cjs{"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/,
+      /^package: reporter-cjs{"test:enqueue":5,"test:dequeue":5,"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/,
     );
   });
 
@@ -120,7 +120,7 @@ describe('node:test reporters', { concurrency: true }, () => {
     assert.strictEqual(child.stderr.toString(), '');
     assert.match(
       child.stdout.toString(),
-      /^package: reporter-esm{"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/,
+      /^package: reporter-esm{"test:enqueue":5,"test:dequeue":5,"test:start":4,"test:pass":2,"test:fail":2,"test:plan":2,"test:diagnostic":\d+}$/,
     );
   });