test_runner: delegate stdout formatting to reporter

Introduce new `TestsStream` event `test:stdout` to delegate
stdout (e.g. `console.log()`) formatting to the reporter.
And patch existing reporters to treat `test:stdout` similar
with `test:diagnostic`.

doc/api/test.md

@@ -1521,6 +1521,14 @@ Emitted when all subtests have completed for a given test.
 
 Emitted when a test starts.
 
+### Event: `'test:stdout'`
+
+* `data` {Object}
+  * `file` {string|undefined} The path of the test file,
+    undefined if test is not through a file.
+  * `line` {string} The line outputted to `stdout`.
+  * `nesting` {number} The nesting level of the test.
+
 ## Class: `TestContext`
 
 <!-- YAML

lib/internal/test_runner/reporter/spec.js

@@ -25,12 +25,14 @@ const colors = {
   'test:fail': red,
   'test:pass': green,
   'test:diagnostic': blue,
+  'test:stdout': blue,
 };
 const symbols = {
   '__proto__': null,
   'test:fail': '\u2716 ',
   'test:pass': '\u2714 ',
   'test:diagnostic': '\u2139 ',
+  'test:stdout': '\u2139 ',
   'test:coverage': '\u2139 ',
   'arrow:right': '\u25B6 ',
   'hyphen:minus': '\uFE63 ',
@@ -117,6 +119,7 @@ class SpecReporter extends Transform {
       case 'test:start':
         ArrayPrototypeUnshift(this.#stack, { __proto__: null, data, type });
         break;
+      case 'test:stdout':
       case 'test:diagnostic':
         return `${colors[type]}${this.#indent(data.nesting)}${symbols[type]}${data.message}${white}\n`;
       case 'test:coverage':

lib/internal/test_runner/reporter/tap.js

@@ -45,6 +45,7 @@ async function * tapReporter(source) {
       case 'test:start':
         yield `${indent(data.nesting)}# Subtest: ${tapEscape(data.name)}\n`;
         break;
+      case 'test:stdout':
       case 'test:diagnostic':
         yield `${indent(data.nesting)}# ${tapEscape(data.message)}\n`;
         break;

lib/internal/test_runner/runner.js

@@ -285,7 +285,7 @@ class FileTest extends Test {
         const message = messages[i];
         this.addToReport({
           __proto__: null,
-          type: 'test:diagnostic',
+          type: 'test:stdout',
           data: { __proto__: null, nesting: 0, file: this.name, message },
         });
       }

lib/internal/test_runner/tests_stream.js

@@ -57,6 +57,10 @@ class TestsStream extends Readable {
     this[kEmitMessage]('test:diagnostic', { __proto__: null, nesting, file, message });
   }
 
+  stdout(nesting, file, line) {
+    this[kEmitMessage]('test:stdout', { __proto__: null, nesting, file, line });
+  }
+
   coverage(nesting, file, summary) {
     this[kEmitMessage]('test:coverage', { __proto__: null, nesting, file, summary });
   }

test/fixtures/test-runner/output/stdout.js

@@ -0,0 +1,9 @@
+// Flags: --no-warnings
+'use strict';
+require('../../../common');
+const test = require('node:test');
+
+test('ok', () => {
+  console.log('print to stdout 1');
+  console.log('print to stdout 2');
+});

test/fixtures/test-runner/output/stdout.snapshot

@@ -0,0 +1,17 @@
+print to stdout 1
+print to stdout 2
+TAP version 13
+# Subtest: ok
+ok 1 - ok
+  ---
+  duration_ms: *
+  ...
+1..1
+# tests 1
+# suites 0
+# pass 1
+# fail 0
+# cancelled 0
+# skipped 0
+# todo 0
+# duration_ms *

test/parallel/test-runner-output.mjs

@@ -46,6 +46,7 @@ const tests = [
   { name: 'test-runner/output/unresolved_promise.js' },
   { name: 'test-runner/output/default_output.js', transform: specTransform, tty: true },
   { name: 'test-runner/output/arbitrary-output.js' },
+  { name: 'test-runner/output/stdout.js' },
 ].map(({ name, tty, transform }) => ({
   name,
   fn: common.mustCall(async () => {