[tool] Conditionalize color on stdout (flutter#4436)

Refactors colorization to a centralized utility file, and makes it all conditional on `stdout` having ANSI escape support. This makes the output more readable on LUCI, which unlike the Cirrus log display doesn't handle ANSI.

Fixes flutter#89392

Author: stuartmorgan-g

script/tool/lib/src/analyze_command.dart

@@ -5,7 +5,7 @@
 import 'package:file/file.dart';
 import 'package:yaml/yaml.dart';
 
-import 'common/core.dart';
+import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/repository_package.dart';
 

script/tool/lib/src/build_examples_command.dart

@@ -6,6 +6,7 @@ import 'package:file/file.dart';
 import 'package:yaml/yaml.dart';
 
 import 'common/core.dart';
+import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
 import 'common/repository_package.dart';

script/tool/lib/src/common/cmake.dart

@@ -6,6 +6,7 @@ import 'package:file/file.dart';
 import 'package:platform/platform.dart';
 
 import 'core.dart';
+import 'output_utils.dart';
 import 'process_runner.dart';
 
 const String _cacheCommandKey = 'CMAKE_COMMAND:INTERNAL';

script/tool/lib/src/common/core.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:colorize/colorize.dart';
 import 'package:file/file.dart';
 import 'package:pub_semver/pub_semver.dart';
 
@@ -69,16 +68,6 @@ bool isPackage(FileSystemEntity entity) {
   return entity.childFile('pubspec.yaml').existsSync();
 }
 
-/// Prints `successMessage` in green.
-void printSuccess(String successMessage) {
-  print(Colorize(successMessage)..green());
-}
-
-/// Prints `errorMessage` in red.
-void printError(String errorMessage) {
-  print(Colorize(errorMessage)..red());
-}
-
 /// Error thrown when a command needs to exit with a non-zero exit code.
 ///
 /// While there is no specific definition of the meaning of different non-zero

script/tool/lib/src/common/output_utils.dart

@@ -0,0 +1,44 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:colorize/colorize.dart';
+import 'package:meta/meta.dart';
+
+export 'package:colorize/colorize.dart' show Styles;
+
+/// True if color should be applied.
+///
+/// Defaults to autodetecting stdout.
+@visibleForTesting
+bool useColorForOutput = stdout.supportsAnsiEscapes;
+
+String _colorizeIfAppropriate(String string, Styles color) {
+  if (!useColorForOutput) {
+    return string;
+  }
+  return Colorize(string).apply(color).toString();
+}
+
+/// Prints [message] in green, if the environment supports color.
+void printSuccess(String message) {
+  print(_colorizeIfAppropriate(message, Styles.GREEN));
+}
+
+/// Prints [message] in yellow, if the environment supports color.
+void printWarning(String message) {
+  print(_colorizeIfAppropriate(message, Styles.YELLOW));
+}
+
+/// Prints [message] in red, if the environment supports color.
+void printError(String message) {
+  print(_colorizeIfAppropriate(message, Styles.RED));
+}
+
+/// Returns [message] with escapes to print it in [color], if the environment
+/// supports color.
+String colorizeString(String message, Styles color) {
+  return _colorizeIfAppropriate(message, color);
+}

script/tool/lib/src/common/package_command.dart

@@ -14,6 +14,7 @@ import 'package:yaml/yaml.dart';
 
 import 'core.dart';
 import 'git_version_finder.dart';
+import 'output_utils.dart';
 import 'process_runner.dart';
 import 'repository_package.dart';
 

script/tool/lib/src/common/package_looping_command.dart

@@ -4,12 +4,12 @@
 
 import 'dart:async';
 
-import 'package:colorize/colorize.dart';
 import 'package:file/file.dart';
 import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 
 import 'core.dart';
+import 'output_utils.dart';
 import 'package_command.dart';
 import 'repository_package.dart';
 
@@ -208,7 +208,7 @@ abstract class PackageLoopingCommand extends PackageCommand {
   /// messages. DO NOT RELY on someone noticing a warning; instead, use it for
   /// things that might be useful to someone debugging an unexpected result.
   void logWarning(String warningMessage) {
-    _printColorized(warningMessage, Styles.YELLOW);
+    printWarning(warningMessage);
     if (_currentPackageEntry != null) {
       _packagesWithWarnings.add(_currentPackageEntry!);
     } else {
@@ -467,7 +467,7 @@ abstract class PackageLoopingCommand extends PackageCommand {
       }
 
       if (!captureOutput) {
-        summary = (Colorize(summary)..apply(style)).toString();
+        summary = colorizeString(summary, style);
       }
       print('  ${entry.package.displayName} - $summary');
     }
@@ -500,7 +500,7 @@ abstract class PackageLoopingCommand extends PackageCommand {
     if (captureOutput) {
       print(message);
     } else {
-      print(Colorize(message)..apply(color));
+      print(colorizeString(message, color));
     }
   }
 

script/tool/lib/src/common/xcode.dart

@@ -7,7 +7,7 @@ import 'dart:io' as io;
 
 import 'package:file/file.dart';
 
-import 'core.dart';
+import 'output_utils.dart';
 import 'process_runner.dart';
 
 const String _xcodeBuildCommand = 'xcodebuild';

script/tool/lib/src/create_all_packages_app_command.dart

@@ -11,6 +11,7 @@ import 'package:pubspec_parse/pubspec_parse.dart';
 
 import 'common/core.dart';
 import 'common/file_utils.dart';
+import 'common/output_utils.dart';
 import 'common/package_command.dart';
 import 'common/process_runner.dart';
 import 'common/pub_utils.dart';

script/tool/lib/src/dart_test_command.dart

@@ -5,6 +5,7 @@
 import 'package:file/file.dart';
 
 import 'common/core.dart';
+import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
 import 'common/pub_utils.dart';