add TAP support

cli.js

@@ -23,6 +23,7 @@ var updateNotifier = require('update-notifier');
 var chalk = require('chalk');
 var Promise = require('bluebird');
 var log = require('./lib/logger');
+var tap = require('./lib/tap');
 var Api = require('./api');
 
 // Bluebird specific
@@ -36,7 +37,8 @@ var cli = meow([
 	'  --init       Add AVA to your project',
 	'  --fail-fast  Stop after first test failure',
 	'  --serial     Run tests serially',
-	'  --require    Module to preload (Can be repeated)',
+	'  --require    Module to preload (Can be repeated)',,
+	'  --tap        Generate TAP output',
 	'',
 	'Examples',
 	'  ava',
@@ -54,7 +56,8 @@ var cli = meow([
 	],
 	boolean: [
 		'fail-fast',
-		'serial'
+		'serial',
+		'tap'
 	]
 });
 
@@ -65,7 +68,11 @@ if (cli.flags.init) {
 	return;
 }
 
-log.write();
+if (cli.flags.tap) {
+	tap.start();
+} else {
+	log.write();
+}
 
 var api = new Api(cli.input, {
 	failFast: cli.flags.failFast,
@@ -74,6 +81,11 @@ var api = new Api(cli.input, {
 });
 
 api.on('test', function (test) {
+	if (cli.flags.tap) {
+		tap.test(test);
+		return;
+	}
+
 	if (test.error) {
 		log.error(test.title, chalk.red(test.error.message));
 	} else {
@@ -92,12 +104,16 @@ api.on('error', function (data) {
 
 api.run()
 	.then(function () {
-		log.write();
-		log.report(api.passCount, api.failCount, api.rejectionCount, api.exceptionCount);
-		log.write();
-
-		if (api.failCount > 0) {
-			log.errors(api.errors);
+		if (cli.flags.tap) {
+			tap.finish(api.passCount, api.failCount);
+		} else {
+			log.write();
+			log.report(api.passCount, api.failCount, api.rejectionCount, api.exceptionCount);
+			log.write();
+
+			if (api.failCount > 0) {
+				log.errors(api.errors);
+			}
 		}
 
 		process.stdout.write('');

lib/tap.js

@@ -0,0 +1,46 @@
+'use strict';
+var format = require('util').format;
+
+// Parses stack trace and extracts original function name, file name and line.
+function getSourceFromStack(stack) {
+	return stack
+		.split('\n')
+		.slice(2, 3)
+		.join('')
+		.replace(/^\s+at /, '');
+}
+
+exports.start = function () {
+	console.log('TAP version 13');
+};
+
+var i = 0;
+
+exports.test = function (test) {
+	var output = [];
+
+	output.push('# ' + test.title);
+
+	if (test.error) {
+		output.push(format('not ok %d - %s', ++i, test.error.message));
+		output.push('  ---');
+		output.push('    operator: ' + test.error.operator);
+		output.push('    expected: ' + test.error.expected);
+		output.push('    actual: ' + test.error.actual);
+		output.push('    at: ' + getSourceFromStack(test.error.stack));
+		output.push('  ...');
+	} else {
+		output.push(format('ok %d - %s', ++i, test.title));
+	}
+
+	console.log(output.join('\n'));
+};
+
+exports.finish = function (passCount, failCount) {
+	console.log();
+	console.log('1..' + (passCount + failCount));
+	console.log('# tests ' + (passCount + failCount));
+	console.log('# pass ' + passCount);
+	console.log('# fail ' + failCount);
+	console.log();
+};