test_runner: delegate stderr and stdout formatting to reporter

Introduce new `TestsStream` events `test:stderr` and `test:stdout`
to delegate `stderr` and `stdout` (e.g. `console.log()`) formatting
to the reporter. And patch existing reporters to:
- Spec: output the message as it is
- TAP: stay the same with existing `test:diagnostic`
PR-URL: #48045Fixes: #48011
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: HinataKah0

doc/api/test.md

@@ -1454,6 +1454,24 @@ Emitted when all subtests have completed for a given test.
 
 Emitted when a test starts.
 
+### Event: `'test:stderr'`
+
+*`data` {Object}
+*`file` {string} The path of the test file.
+*`message` {string} The message written to `stderr`.
+
+Emitted when a running test writes to `stderr`.
+This event is only emitted if `--test` flag is passed.
+
+### Event: `'test:stdout'`
+
+*`data` {Object}
+*`file` {string} The path of the test file.
+*`message` {string} The message written to `stdout`.
+
+Emitted when a running test writes to `stdout`.
+This event is only emitted if `--test` flag is passed.
+
 ## Class: `TestContext`
 
 <!-- YAML

lib/internal/test_runner/reporter/spec.js

@@ -117,6 +117,9 @@ class SpecReporter extends Transform {
 case'test:start':
 ArrayPrototypeUnshift(this.#stack,{__proto__: null, data, type });
 break;
+case'test:stderr':
+case'test:stdout':
+return`${data.message}\n`;
 case'test:diagnostic':
 return`${colors[type]}${this.#indent(data.nesting)}${symbols[type]}${data.message}${white}\n`;
 case'test:coverage':

lib/internal/test_runner/reporter/tap.js

@@ -45,6 +45,8 @@ async function * tapReporter(source) {
 case'test:start':
 yield`${indent(data.nesting)}# Subtest: ${tapEscape(data.name)}\n`;
 break;
+case'test:stderr':
+case'test:stdout':
 case'test:diagnostic':
 yield`${indent(data.nesting)}# ${tapEscape(data.message)}\n`;
 break;

lib/internal/test_runner/runner.js

@@ -284,8 +284,8 @@ class FileTest extends Test {
 constmessage=messages[i];
 this.addToReport({
 __proto__: null,
-type: 'test:diagnostic',
-data: {__proto__: null,nesting: 0,file: this.name, message },
+type: 'test:stdout',
+data: {__proto__: null,file: this.name, message },
 });
 }
 }
@@ -356,13 +356,12 @@ function runTestFile(path, root, inspectPort, filesWatcher, testNamePatterns) {
 }
 
 // stderr cannot be treated as TAP, per the spec. However, we want to
-// surface stderr lines as TAP diagnostics to improve the DX. Inject
-// each line into the test output as an unknown token as if it came
-// from the TAP parser.
+// surface stderr lines to improve the DX. Inject each line into the
+// test output as an unknown token as if it came from the TAP parser.
 subtest.addToReport({
 __proto__: null,
-type: 'test:diagnostic',
-data: {__proto__: null,nesting: 0,file: path,message: line},
+type: 'test:stderr',
+data: {__proto__: null,file: path,message: line},
 });
 });
 

lib/internal/test_runner/tests_stream.js

@@ -57,6 +57,14 @@ class TestsStream extends Readable {
 this[kEmitMessage]('test:diagnostic',{__proto__: null, nesting, file, message });
 }
 
+stderr(file,message){
+this[kEmitMessage]('test:stderr',{__proto__: null, file, message });
+}
+
+stdout(file,message){
+this[kEmitMessage]('test:stdout',{__proto__: null, file, message });
+}
+
 coverage(nesting,file,summary){
 this[kEmitMessage]('test:coverage',{__proto__: null, nesting, file, summary });
 }