test_runner: expose reporter for use in run api

doc/api/test.md

@@ -546,6 +546,16 @@
 to the test runner's output is required, use the events emitted by the
 {TestsStream}.
 
+The reporters are available via the `node:test/reporters` module:
+
+```mjs
+import { tap, spec, dot } from 'node:test/reporters';
+```
+
+```cjs
+const { tap, spec, dot } = require('node:test/reporters');
+```
+
 ### Custom reporters
 
 [`--test-reporter`][] can be used to specify a path to custom reporter.
@@ -739,8 +749,18 @@
     **Default:** `undefined`.
 * Returns: {TestsStream}
 
-```js
+```mjs
+import { tap } from 'node:test/reporters';
+
+run({ files: [path.resolve('./tests/test.js')] })
+  .compose(tap)
+  .pipe(process.stdout);
+```
+```cjs
+const { tap } = require('node:test/reporters');
+
 run({ files: [path.resolve('./tests/test.js')] })
+  .compose(tap)
   .pipe(process.stdout);
 ```
 

lib/test/reporters.js

@@ -0,0 +1,11 @@
+'use strict';
+
+const dot = require('internal/test_runner/reporter/dot');
+const spec = require('internal/test_runner/reporter/spec');
+const tap = require('internal/test_runner/reporter/tap');
+
+module.exports = {
+  dot,
+  spec,
+  tap,
+};

test/parallel/test-runner-run.mjs

@@ -2,6 +2,8 @@ import * as common from '../common/index.mjs';
 import * as fixtures from '../common/fixtures.mjs';
 import { join } from 'node:path';
 import { describe, it, run } from 'node:test';
+import { Writable } from 'node:stream';
+import { dot } from 'node:test/reporters';
 import assert from 'node:assert';
 
 const testFixtures = fixtures.path('test-runner');
@@ -65,4 +67,22 @@ describe('require(\'node:test\').run', { concurrency: true }, () => {
         code: 'ERR_INVALID_ARG_TYPE'
       }));
   });
+
+  it('should be piped with dot', (ctx, done) => {
+    const written = [];
+    const writer = new Writable();
+    writer._write = function(chunk, encoding, cb) {
+      written.push(chunk.toString());
+      process.nextTick(cb);
+    };
+    function finish() {
+      assert.deepStrictEqual(written, [
+        '.',
+        '\n',
+      ]);
+      done();
+    }
+    writer.on('finish', finish);
+    run({ files: [join(testFixtures, 'test/random.cjs')] }).compose(dot).pipe(writer);
+  });
 });