test_runner: default to spec reporter when on TTY environment

PR-URL: #46969
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: MoLow

doc/api/test.md

@@ -522,8 +522,7 @@ flags for the test runner to use a specific reporter.
 The following built-reporters are supported:
 
 * `tap`
-  The `tap` reporter is the default reporter used by the test runner. It outputs
-  the test results in the [TAP][] format.
+  The `tap` reporter outputs the test results in the [TAP][] format.
 
 * `spec`
   The `spec` reporter outputs the test results in a human-readable format.
@@ -533,6 +532,9 @@ The following built-reporters are supported:
   where each passing test is represented by a `.`,
   and each failing test is represented by a `X`.
 
+When `stdout` is a [TTY][], the `spec` reporter is used by default.
+Otherwise, the `tap` reporter is used by default.
+
 ### Custom reporters
 
 [`--test-reporter`][] can be used to specify a path to custom reporter.
@@ -1770,6 +1772,7 @@ added:
   aborted.
 
 [TAP]: https://testanything.org/
+[TTY]: tty.md
 [`--experimental-test-coverage`]: cli.md#--experimental-test-coverage
 [`--import`]: cli.md#--importmodule
 [`--test-name-pattern`]: cli.md#--test-name-pattern

lib/internal/test_runner/utils.js

@@ -98,7 +98,7 @@ const kBuiltinReporters = new SafeMap([
   ['tap', 'internal/test_runner/reporter/tap'],
 ]);
 
-const kDefaultReporter = 'tap';
+const kDefaultReporter = process.stdout.isTTY ? 'spec' : 'tap';
 const kDefaultDestination = 'stdout';
 
 function tryBuiltinReporter(name) {

test/pseudo-tty/test_runner_default_reporter.js

@@ -0,0 +1,11 @@
+'use strict';
+process.env.FORCE_COLOR = '1';
+delete process.env.NODE_DISABLE_COLORS;
+delete process.env.NO_COLOR;
+
+require('../common');
+const test = require('node:test');
+
+test('should pass', () => {});
+test('should fail', () => { throw new Error('fail'); });
+test('should skip', { skip: true }, () => {});

test/pseudo-tty/test_runner_default_reporter.out

@@ -0,0 +1,19 @@
+[32m* should pass [90m(*ms)[39m[39m
+[31m* should fail [90m(*ms)[39m
+  Error: fail
+      at * [90m(*)[39m
+  [90m    at *[39m
+  [90m    at *[39m
+  [90m    at *[39m
+  [90m    at *[39m
+  [90m    at *[39m
+  [90m    at *[39m
+**
+[90m* should skip [90m(*ms)[39m # SKIP[39m
+[34m* tests 3[39m
+[34m* pass 1[39m
+[34m* fail 1[39m
+[34m* cancelled 0[39m
+[34m* skipped 1[39m
+[34m* todo 0[39m
+[34m* duration_ms *[39m