scripts/fxtest/lib/output_formatter.dart - fuchsia - Git at Google

 // Copyright 2019 The Fuchsia 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:fxtest/fxtest.dart';
 import 'package:io/ansi.dart';
 import 'package:meta/meta.dart';

 class Emoji {
   final String emoji;
   final String fallback;
   Emoji(this.emoji, this.fallback);

   static final Emoji party = Emoji('🎉', '!');
   static final Emoji thinking = Emoji('🤔', '?');
   static final Emoji check = Emoji('✅', '√');
   static final Emoji x = Emoji('❌', 'F');
 }

 abstract class OutputFormatter {
   final bool isVerbose;
   final bool simpleOutput;
   final bool hasRealTimeOutput;
   final Duration slowTestThreshold;
   final List<TestInfo> _infoEvents;
   final List<TestStarted> _testStartedEvents;
   final List<TestResult> _testResultEvents;
   final OutputBuffer _buffer;
   DateTime _testSuiteStartTime;
   DateTime _lastTestStartTime;
   bool _hasStartedTests;
   bool _currentTestIsSlow;
   bool _lastTestHadOutput;
   int _numPassed;
   int _numRun;
   int _numFailed;

   OutputFormatter({
     @required this.isVerbose,
     @required this.hasRealTimeOutput,
     @required this.slowTestThreshold,
     this.simpleOutput = false,
     OutputBuffer buffer,
   })  : _testResultEvents = [],
         _infoEvents = [],
         _testStartedEvents = [],
         _numPassed = 0,
         _numRun = 0,
         _numFailed = 0,
         _buffer = buffer ?? OutputBuffer.realIO(),
         _currentTestIsSlow = false,
         _hasStartedTests = false,
         _lastTestHadOutput = false;

   factory OutputFormatter.fromConfig(
     TestsConfig testsConfig, {
     OutputBuffer buffer,
   }) {
     if (testsConfig.flags.infoOnly) {
       return InfoFormatter();
     }
     var slowTestThreshold = testsConfig.flags.slowThreshold > 0
         ? Duration(seconds: testsConfig.flags.slowThreshold)
         : null;
     return StandardOutputFormatter(
       buffer: buffer,
       hasRealTimeOutput: testsConfig.flags.allOutput,
       isVerbose: testsConfig.flags.isVerbose || testsConfig.flags.allOutput,
       simpleOutput: testsConfig.flags.simpleOutput,
       slowTestThreshold: slowTestThreshold,
     );
   }

   bool get hasStartedTests => _hasStartedTests;
   int get numFailures => _numFailed;

   String get testExecutionTime => _getExecutionTime(_lastTestStartTime);
   String get suiteExecutionTime => _getExecutionTime(_testSuiteStartTime);

   String _getExecutionTime(DateTime _startTime) {
     Duration elapsedTime = DateTime.now().difference(_startTime);
     String minutes = elapsedTime.inMinutes.toString().padLeft(2, '0');
     String seconds = (elapsedTime.inSeconds % 60).toString().padLeft(2, '0');
     return '$minutes:$seconds';
   }

   String get ratioDisplay {
     var passed = colorize(_numPassed.toString(), [green]);
     var run = colorize(_numRun.toString(), [numFailures == 0 ? green : red]);
     return '[$passed/$run]';
   }

   /// Future that resolves when the stdout closes for any reason
   Future get stdOutClosedFuture => _buffer.stdOutClosedFuture();

   /// Pass-thru to the actual buffer's close method
   void close() => _buffer.close();

   void forcefullyClose() => _buffer.forcefullyClose();

   String colorize(String content, Iterable<AnsiCode> args) {
     return simpleOutput ? content : wrapWith(content, args);
   }

   String addEmoji(Emoji emoji) {
     return simpleOutput ? emoji.fallback : emoji.emoji;
   }

   /// Accepts a [TestEvent] and updates the output buffer.
   void update(TestEvent event) {
     if (event is TestInfo) {
       _infoEvents.add(event);
     } else if (event is TestStarted) {
       _testStartedEvents.add(event);
     } else if (event is TestResult) {
       _testResultEvents.add(event);
     }
     _updateAfterEvent(event);
   }

   void _updateAfterEvent(TestEvent event) {
     var _now = DateTime.now();
     if (event is BeginningTests) {
       _hasStartedTests = true;
       _testSuiteStartTime = _now;
     } else if (event is TestStarted) {
       _currentTestIsSlow = false;
       _lastTestStartTime = _now;
       _numRun += 1;
       _handleTestStarted(event);
     } else if (event is TestResult) {
       (event.isSuccess) ? _numPassed += 1 : _numFailed += 1;
       _handleTestResult(event);
     } else if (event is TestOutputEvent) {
       // This must always come before `TestInfo`, because it is a subclass
       _handleTestOutputEvent(event);
     } else if (event is TimeElapsedEvent) {
       // We do nothing with time events during realtime output -- the user is
       // already getting constant updates
       if (hasRealTimeOutput) return;
       if (event.timeElapsed >= slowTestThreshold) {
         if (!_currentTestIsSlow) {
           _currentTestIsSlow = true;
           _handleSlowTest(event);
         }
       }
       _handleTimeElapsedEvent(event);
     } else if (event is TestInfo) {
       _handleTestInfo(event);
     } else if (event is FatalError) {
       stderr.writeln(event.message);
       _finalizeOutput();
     } else if (event is AllTestsCompleted) {
       _finalizeOutput();
     }
   }

   /// Handles every [TimeElapsedEvent] instance, regardless of whether the test
   /// has yet been deemed "slow".
   void _handleTimeElapsedEvent(TimeElapsedEvent event);

   /// Handles only the first [TimeElapsedEvent] that passes the slow threshold.
   void _handleSlowTest(TimeElapsedEvent event) {
     var hint =
         colorize('(adjust this value with the -s|--slow flag)', [darkGray]);
     _buffer
       ..addLine(
         colorize(
             ' >> Runtime has exceeded ${slowTestThreshold.inSeconds} '
             'seconds $hint',
             [magenta]),
       )
       ..addLines(event.output);
   }

   /// Generic info events handler.
   void _handleTestInfo(TestInfo event);

   /// Handler for the stream of stdout and stderr content produced by running
   /// tests.
   void _handleTestOutputEvent(TestOutputEvent event) {
     if (_currentTestIsSlow || hasRealTimeOutput) {
       _lastTestHadOutput = true;
       return _handleTestInfo(event);
     }
   }

   /// Handles the event that fires as each test beings execution.
   void _handleTestStarted(TestStarted event);

   /// Handles the event that fires as each test completes execution.
   void _handleTestResult(TestResult event);

   /// Produces summarizing content for the user. Called once.
   void _finalizeOutput();

   void _reportSummary() {
     _buffer.reduceEmptyRowsTo(0);
     if (_testResultEvents.isEmpty) {
       _buffer.addLines(['Ran zero tests']);
       return;
     }
     String failures = numFailures != 1 ? 'failures' : 'failure';
     String verb = _testResultEvents.last.isDryRun ? 'Faked' : 'Ran';
     var verboseHint = !isVerbose && !cleanEndOfOutput
         ? wrapWith(' (use the -v flag to see each test)', [darkGray])
         : '';
     String summary =
         '$verb ${_testResultEvents.length} tests with $numFailures $failures$verboseHint';
     if (numFailures == 0) {
       summary = '${addEmoji(Emoji.party)}  ${colorize(summary, [
         green
       ])} ${addEmoji(Emoji.party)}';
     }
     _buffer.addLines([summary]);
   }

   bool get cleanEndOfOutput =>
       // Did the last test end with verbose output?
       !isVerbose &&
       !_currentTestIsSlow &&
       !hasRealTimeOutput &&
       // Did the last test fail?
       (_testResultEvents.isNotEmpty && _testResultEvents.last.isSuccess);
 }

 /// Default output wrapper inspired by both Dart's test runner and fx build's
 /// standard output.
 ///
 /// Aims to print something like this (when no tests fail):
 /// ```txt
 ///  $ fx test --limit 2 -v
 ///    Found N total tests in //out/default/tests.json
 ///    Will run 2 tests
 ///
 ///    [2/2] 00:01 √ All tests completed
 ///
 ///    🎉  Ran 2 tests with 0 failures 🎉
 /// ```
 class StandardOutputFormatter extends OutputFormatter {
   StandardOutputFormatter({
     @required bool hasRealTimeOutput,
     bool simpleOutput = true,
     Duration slowTestThreshold,
     OutputBuffer buffer,
     bool isVerbose,
   }) : super(
           isVerbose: isVerbose,
           hasRealTimeOutput: hasRealTimeOutput,
           simpleOutput: simpleOutput,
           slowTestThreshold: slowTestThreshold,
           buffer: buffer,
         );

   @override
   void _handleTestInfo(TestInfo event) {
     _buffer.addLines([
       // Padding for info events that appear in the middle of the result stream
       if (hasStartedTests && event.requiresPadding)
         ' ',
       // The message itself
       event.message,
       // Padding for info events that appear in the middle of the result stream
       if (hasStartedTests && event.requiresPadding)
         ' ',
     ]);
   }

   @override
   void _handleTimeElapsedEvent(TimeElapsedEvent event) {}

   @override
   void _handleTestStarted(TestStarted event) {
     String testName = colorize(event.testName, [cyan]);
     // Add some padding for our first test event
     if (_testStartedEvents.length == 1) {
       _buffer.addLine('');
     }
     _lastTestHadOutput = false;

     var output =
         '$ratioDisplay $testExecutionTime ${addEmoji(Emoji.thinking)}  $testName';
     if (isVerbose) {
       _buffer.addLine(output);
     } else {
       // Add some more padding for our first test event
       if (_testStartedEvents.length == 1) {
         _buffer.addLine('');
       }
       _buffer.updateLines([output]);
     }
   }

   /// Prints something like "[numPassed/numRun] TT:TT <emoji> <test-name>"
   @override
   void _handleTestResult(TestResult event) {
     if (_lastTestHadOutput) _buffer.addLines(['']);

     String testName = colorize(event.testName, [cyan]);
     String emoji = event.isDryRun
         ? colorize('(dry run)', [darkGray])
         : event.isSuccess
             ? '${addEmoji(Emoji.check)} '
             : '${addEmoji(Emoji.x)} ';

     var output = '$ratioDisplay $testExecutionTime $emoji $testName';

     // When piping realtime output to the user, we don't want to remove the
     // last line. Usually, the last line is what indicates a new test is underway,
     // which we replace in favor of the results line, but in this scenario,
     // it's likely some output from the test.
     // We do the same for slow tests because we print realtime output for them.
     if (hasRealTimeOutput || _currentTestIsSlow) {
       _buffer.addLines([output]);
     } else {
       _buffer.updateLines([output]);
     }

     // Report for failed messages
     if (!event.isSuccess && event.message != null) {
       // But only if not already doing realtime
       if (!hasRealTimeOutput && !_currentTestIsSlow) {
         _buffer.addLines([event.message, '']);
       }
     }
   }

   void _finalizeLastTestLine() {
     if (!cleanEndOfOutput) return;
     var verboseHint = wrapWith(
       ' (use the -v flag to see each test)',
       [darkGray],
     );
     _buffer.updateLines([
       '$ratioDisplay $suiteExecutionTime All tests completed$verboseHint',
     ]);
   }

   @override
   void _finalizeOutput() {
     _finalizeLastTestLine();
     _reportSummary();
   }
 }

 /// Special formatter for when the caller is only using this tool to translate
 /// shorthand test invocation patterns into fully-formed patterns.
 ///
 /// This formatter is not intended to be paired with an actual test suite
 /// execution, and as such, ignores all events except `TestStarted`, which it
 /// uses to print a fully hydrated test invocation pattern.
 class InfoFormatter extends OutputFormatter {
   InfoFormatter()
       : super(
           buffer: OutputBuffer.realIO(cursorStartsOnNewLine: true),
           hasRealTimeOutput: false,
           slowTestThreshold: Duration(seconds: 0),
           isVerbose: false,
         );

   @override
   void _handleTestInfo(TestInfo event) {}
   @override
   void _handleTestStarted(TestStarted event) {
     _buffer.addLines([
       ...infoPrint(event.testDefinition),
       '',
     ]);
   }

   @override
   void _handleTestResult(TestResult event) {}
   @override
   void _finalizeOutput() {}
   @override
   void _handleTimeElapsedEvent(TimeElapsedEvent event) {}
 }

 List<String> infoPrint(TestDefinition testDefinition) {
   var command =
       testDefinition.executionHandle.getInvocationTokens(const []).toString();
   return <String>[
     _isTruthy(command) ? 'command: $command' : null,
     _isTruthy(testDefinition.cpu) ? 'cpu: ${testDefinition.cpu}' : null,
     _isTruthy(testDefinition.depsFile)
         ? 'depsFile: ${testDefinition.depsFile}'
         : null,
     _isTruthy(testDefinition.name) ? 'name: ${testDefinition.name}' : null,
     _isTruthy(testDefinition.os) ? 'os: ${testDefinition.os}' : null,
     _isTruthy(testDefinition.packageUrl)
         ? 'package_url: ${testDefinition.packageUrl}'
         : null,
     _isTruthy(testDefinition.label) ? 'label: ${testDefinition.label}' : null,
     _isTruthy(testDefinition.path) ? 'path: ${testDefinition.path}' : null,
   ].where((_val) => _val != null).toList()
     ..sort();
 }

 bool _isTruthy(String val) => val != null && val != '';
	// Copyright 2019 The Fuchsia 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:fxtest/fxtest.dart';
	import 'package:io/ansi.dart';
	import 'package:meta/meta.dart';

	class Emoji {
	final String emoji;
	final String fallback;
	Emoji(this.emoji, this.fallback);

	static final Emoji party = Emoji('🎉', '!');
	static final Emoji thinking = Emoji('🤔', '?');
	static final Emoji check = Emoji('✅', '√');
	static final Emoji x = Emoji('❌', 'F');
	}

	abstract class OutputFormatter {
	final bool isVerbose;
	final bool simpleOutput;
	final bool hasRealTimeOutput;
	final Duration slowTestThreshold;
	final List<TestInfo> _infoEvents;
	final List<TestStarted> _testStartedEvents;
	final List<TestResult> _testResultEvents;
	final OutputBuffer _buffer;
	DateTime _testSuiteStartTime;
	DateTime _lastTestStartTime;
	bool _hasStartedTests;
	bool _currentTestIsSlow;
	bool _lastTestHadOutput;
	int _numPassed;
	int _numRun;
	int _numFailed;

	OutputFormatter({
	@required this.isVerbose,
	@required this.hasRealTimeOutput,
	@required this.slowTestThreshold,
	this.simpleOutput = false,
	OutputBuffer buffer,
	}) : _testResultEvents = [],
	_infoEvents = [],
	_testStartedEvents = [],
	_numPassed = 0,
	_numRun = 0,
	_numFailed = 0,
	_buffer = buffer ?? OutputBuffer.realIO(),
	_currentTestIsSlow = false,
	_hasStartedTests = false,
	_lastTestHadOutput = false;

	factory OutputFormatter.fromConfig(
	TestsConfig testsConfig, {
	OutputBuffer buffer,
	}) {
	if (testsConfig.flags.infoOnly) {
	return InfoFormatter();
	}
	var slowTestThreshold = testsConfig.flags.slowThreshold > 0
	? Duration(seconds: testsConfig.flags.slowThreshold)
	: null;
	return StandardOutputFormatter(
	buffer: buffer,
	hasRealTimeOutput: testsConfig.flags.allOutput,
	isVerbose: testsConfig.flags.isVerbose \|\| testsConfig.flags.allOutput,
	simpleOutput: testsConfig.flags.simpleOutput,
	slowTestThreshold: slowTestThreshold,
	);
	}

	bool get hasStartedTests => _hasStartedTests;
	int get numFailures => _numFailed;

	String get testExecutionTime => _getExecutionTime(_lastTestStartTime);
	String get suiteExecutionTime => _getExecutionTime(_testSuiteStartTime);

	String _getExecutionTime(DateTime _startTime) {
	Duration elapsedTime = DateTime.now().difference(_startTime);
	String minutes = elapsedTime.inMinutes.toString().padLeft(2, '0');
	String seconds = (elapsedTime.inSeconds % 60).toString().padLeft(2, '0');
	return '$minutes:$seconds';
	}

	String get ratioDisplay {
	var passed = colorize(_numPassed.toString(), [green]);
	var run = colorize(_numRun.toString(), [numFailures == 0 ? green : red]);
	return '[$passed/$run]';
	}

	/// Future that resolves when the stdout closes for any reason
	Future get stdOutClosedFuture => _buffer.stdOutClosedFuture();

	/// Pass-thru to the actual buffer's close method
	void close() => _buffer.close();

	void forcefullyClose() => _buffer.forcefullyClose();

	String colorize(String content, Iterable<AnsiCode> args) {
	return simpleOutput ? content : wrapWith(content, args);
	}

	String addEmoji(Emoji emoji) {
	return simpleOutput ? emoji.fallback : emoji.emoji;
	}

	/// Accepts a [TestEvent] and updates the output buffer.
	void update(TestEvent event) {
	if (event is TestInfo) {
	_infoEvents.add(event);
	} else if (event is TestStarted) {
	_testStartedEvents.add(event);
	} else if (event is TestResult) {
	_testResultEvents.add(event);
	}
	_updateAfterEvent(event);
	}

	void _updateAfterEvent(TestEvent event) {
	var _now = DateTime.now();
	if (event is BeginningTests) {
	_hasStartedTests = true;
	_testSuiteStartTime = _now;
	} else if (event is TestStarted) {
	_currentTestIsSlow = false;
	_lastTestStartTime = _now;
	_numRun += 1;
	_handleTestStarted(event);
	} else if (event is TestResult) {
	(event.isSuccess) ? _numPassed += 1 : _numFailed += 1;
	_handleTestResult(event);
	} else if (event is TestOutputEvent) {
	// This must always come before `TestInfo`, because it is a subclass
	_handleTestOutputEvent(event);
	} else if (event is TimeElapsedEvent) {
	// We do nothing with time events during realtime output -- the user is
	// already getting constant updates
	if (hasRealTimeOutput) return;
	if (event.timeElapsed >= slowTestThreshold) {
	if (!_currentTestIsSlow) {
	_currentTestIsSlow = true;
	_handleSlowTest(event);
	}
	}
	_handleTimeElapsedEvent(event);
	} else if (event is TestInfo) {
	_handleTestInfo(event);
	} else if (event is FatalError) {
	stderr.writeln(event.message);
	_finalizeOutput();
	} else if (event is AllTestsCompleted) {
	_finalizeOutput();
	}
	}

	/// Handles every [TimeElapsedEvent] instance, regardless of whether the test
	/// has yet been deemed "slow".
	void _handleTimeElapsedEvent(TimeElapsedEvent event);

	/// Handles only the first [TimeElapsedEvent] that passes the slow threshold.
	void _handleSlowTest(TimeElapsedEvent event) {
	var hint =
	colorize('(adjust this value with the -s\|--slow flag)', [darkGray]);
	_buffer
	..addLine(
	colorize(
	' >> Runtime has exceeded ${slowTestThreshold.inSeconds} '
	'seconds $hint',
	[magenta]),
	)
	..addLines(event.output);
	}

	/// Generic info events handler.
	void _handleTestInfo(TestInfo event);

	/// Handler for the stream of stdout and stderr content produced by running
	/// tests.
	void _handleTestOutputEvent(TestOutputEvent event) {
	if (_currentTestIsSlow \|\| hasRealTimeOutput) {
	_lastTestHadOutput = true;
	return _handleTestInfo(event);
	}
	}

	/// Handles the event that fires as each test beings execution.
	void _handleTestStarted(TestStarted event);

	/// Handles the event that fires as each test completes execution.
	void _handleTestResult(TestResult event);

	/// Produces summarizing content for the user. Called once.
	void _finalizeOutput();

	void _reportSummary() {
	_buffer.reduceEmptyRowsTo(0);
	if (_testResultEvents.isEmpty) {
	_buffer.addLines(['Ran zero tests']);
	return;
	}
	String failures = numFailures != 1 ? 'failures' : 'failure';
	String verb = _testResultEvents.last.isDryRun ? 'Faked' : 'Ran';
	var verboseHint = !isVerbose && !cleanEndOfOutput
	? wrapWith(' (use the -v flag to see each test)', [darkGray])
	: '';
	String summary =
	'$verb ${_testResultEvents.length} tests with $numFailures $failures$verboseHint';
	if (numFailures == 0) {
	summary = '${addEmoji(Emoji.party)} ${colorize(summary, [
	green
	])} ${addEmoji(Emoji.party)}';
	}
	_buffer.addLines([summary]);
	}

	bool get cleanEndOfOutput =>
	// Did the last test end with verbose output?
	!isVerbose &&
	!_currentTestIsSlow &&
	!hasRealTimeOutput &&
	// Did the last test fail?
	(_testResultEvents.isNotEmpty && _testResultEvents.last.isSuccess);
	}

	/// Default output wrapper inspired by both Dart's test runner and fx build's
	/// standard output.
	///
	/// Aims to print something like this (when no tests fail):
	/// ```txt
	/// $ fx test --limit 2 -v
	/// Found N total tests in //out/default/tests.json
	/// Will run 2 tests
	///
	/// [2/2] 00:01 √ All tests completed
	///
	/// 🎉 Ran 2 tests with 0 failures 🎉
	/// ```
	class StandardOutputFormatter extends OutputFormatter {
	StandardOutputFormatter({
	@required bool hasRealTimeOutput,
	bool simpleOutput = true,
	Duration slowTestThreshold,
	OutputBuffer buffer,
	bool isVerbose,
	}) : super(
	isVerbose: isVerbose,
	hasRealTimeOutput: hasRealTimeOutput,
	simpleOutput: simpleOutput,
	slowTestThreshold: slowTestThreshold,
	buffer: buffer,
	);

	@override
	void _handleTestInfo(TestInfo event) {
	_buffer.addLines([
	// Padding for info events that appear in the middle of the result stream
	if (hasStartedTests && event.requiresPadding)
	' ',
	// The message itself
	event.message,
	// Padding for info events that appear in the middle of the result stream
	if (hasStartedTests && event.requiresPadding)
	' ',
	]);
	}

	@override
	void _handleTimeElapsedEvent(TimeElapsedEvent event) {}

	@override
	void _handleTestStarted(TestStarted event) {
	String testName = colorize(event.testName, [cyan]);
	// Add some padding for our first test event
	if (_testStartedEvents.length == 1) {
	_buffer.addLine('');
	}
	_lastTestHadOutput = false;

	var output =
	'$ratioDisplay $testExecutionTime ${addEmoji(Emoji.thinking)} $testName';
	if (isVerbose) {
	_buffer.addLine(output);
	} else {
	// Add some more padding for our first test event
	if (_testStartedEvents.length == 1) {
	_buffer.addLine('');
	}
	_buffer.updateLines([output]);
	}
	}

	/// Prints something like "[numPassed/numRun] TT:TT <emoji> <test-name>"
	@override
	void _handleTestResult(TestResult event) {
	if (_lastTestHadOutput) _buffer.addLines(['']);

	String testName = colorize(event.testName, [cyan]);
	String emoji = event.isDryRun
	? colorize('(dry run)', [darkGray])
	: event.isSuccess
	? '${addEmoji(Emoji.check)} '
	: '${addEmoji(Emoji.x)} ';

	var output = '$ratioDisplay $testExecutionTime $emoji $testName';

	// When piping realtime output to the user, we don't want to remove the
	// last line. Usually, the last line is what indicates a new test is underway,
	// which we replace in favor of the results line, but in this scenario,
	// it's likely some output from the test.
	// We do the same for slow tests because we print realtime output for them.
	if (hasRealTimeOutput \|\| _currentTestIsSlow) {
	_buffer.addLines([output]);
	} else {
	_buffer.updateLines([output]);
	}

	// Report for failed messages
	if (!event.isSuccess && event.message != null) {
	// But only if not already doing realtime
	if (!hasRealTimeOutput && !_currentTestIsSlow) {
	_buffer.addLines([event.message, '']);
	}
	}
	}

	void _finalizeLastTestLine() {
	if (!cleanEndOfOutput) return;
	var verboseHint = wrapWith(
	' (use the -v flag to see each test)',
	[darkGray],
	);
	_buffer.updateLines([
	'$ratioDisplay $suiteExecutionTime All tests completed$verboseHint',
	]);
	}

	@override
	void _finalizeOutput() {
	_finalizeLastTestLine();
	_reportSummary();
	}
	}

	/// Special formatter for when the caller is only using this tool to translate
	/// shorthand test invocation patterns into fully-formed patterns.
	///
	/// This formatter is not intended to be paired with an actual test suite
	/// execution, and as such, ignores all events except `TestStarted`, which it
	/// uses to print a fully hydrated test invocation pattern.
	class InfoFormatter extends OutputFormatter {
	InfoFormatter()
	: super(
	buffer: OutputBuffer.realIO(cursorStartsOnNewLine: true),
	hasRealTimeOutput: false,
	slowTestThreshold: Duration(seconds: 0),
	isVerbose: false,
	);

	@override
	void _handleTestInfo(TestInfo event) {}
	@override
	void _handleTestStarted(TestStarted event) {
	_buffer.addLines([
	...infoPrint(event.testDefinition),
	'',
	]);
	}

	@override
	void _handleTestResult(TestResult event) {}
	@override
	void _finalizeOutput() {}
	@override
	void _handleTimeElapsedEvent(TimeElapsedEvent event) {}
	}

	List<String> infoPrint(TestDefinition testDefinition) {
	var command =
	testDefinition.executionHandle.getInvocationTokens(const []).toString();
	return <String>[
	_isTruthy(command) ? 'command: $command' : null,
	_isTruthy(testDefinition.cpu) ? 'cpu: ${testDefinition.cpu}' : null,
	_isTruthy(testDefinition.depsFile)
	? 'depsFile: ${testDefinition.depsFile}'
	: null,
	_isTruthy(testDefinition.name) ? 'name: ${testDefinition.name}' : null,
	_isTruthy(testDefinition.os) ? 'os: ${testDefinition.os}' : null,
	_isTruthy(testDefinition.packageUrl)
	? 'package_url: ${testDefinition.packageUrl}'
	: null,
	_isTruthy(testDefinition.label) ? 'label: ${testDefinition.label}' : null,
	_isTruthy(testDefinition.path) ? 'path: ${testDefinition.path}' : null,
	].where((_val) => _val != null).toList()
	..sort();
	}

	bool _isTruthy(String val) => val != null && val != '';