Improve YAML blocks in TAP reporter (#1301)

* Properly dump errors
* Only print actual and expected values if they're present, and strings.
This assumes they're serialized in the test workers
* Strip ANSI from actual and expected values
* Print additional name & message properties
* Determine 'at' value similar to serialize-error.js. Recompute since
here we want the full line
* Print unhandled errors using the same logic

lib/reporters/tap.js

@@ -1,14 +1,37 @@
 'use strict';
 const format = require('util').format;
+const indentString = require('indent-string');
 const stripAnsi = require('strip-ansi');
+const yaml = require('js-yaml');
+const extractStack = require('../extract-stack');
 
 // Parses stack trace and extracts original function name, file name and line
-function getSourceFromStack(stack, index) {
-	return stack
-		.split('\n')
-		.slice(index, index + 1)
-		.join('')
-		.replace(/^\s+ /, '');
+function getSourceFromStack(stack) {
+	return extractStack(stack).split('\n')[0];
+}
+
+function dumpError(error, includeMessage) {
+	const obj = {};
+	if (error.name) {
+		obj.name = error.name;
+	}
+	if (includeMessage && error.message) {
+		obj.message = error.message;
+	}
+	if (error.operator) {
+		obj.operator = error.operator;
+	}
+	if (typeof error.actual === 'string') { // Be sure to print empty strings, which are falsy
+		obj.actual = stripAnsi(error.actual);
+	}
+	if (typeof error.expected === 'string') { // Be sure to print empty strings, which are falsy
+		obj.expected = stripAnsi(error.expected);
+	}
+	if (error.stack) {
+		obj.at = getSourceFromStack(error.stack);
+	}
+
+	return `  ---\n${indentString(yaml.safeDump(obj).trim(), 4)}\n  ...`;
 }
 
 class TapReporter {
@@ -36,12 +59,7 @@ class TapReporter {
 			output = [
 				'# ' + title,
 				format('not ok %d - %s', ++this.i, title),
-				'  ---',
-				'    operator: ' + test.error.operator,
-				'    expected: ' + test.error.expected,
-				'    actual: ' + test.error.actual,
-				'    at: ' + getSourceFromStack(test.error.stack, 1),
-				'  ...'
+				dumpError(test.error, true)
 			];
 		} else {
 			output = [
@@ -59,12 +77,7 @@ class TapReporter {
 		];
 		// AvaErrors don't have stack traces
 		if (err.type !== 'exception' || err.name !== 'AvaError') {
-			output.push(
-				'  ---',
-				'    name: ' + err.name,
-				'    at: ' + getSourceFromStack(err.stack, 1),
-				'  ...'
-			);
+			output.push(dumpError(err, false));
 		}
 
 		return output.join('\n');

package.json

@@ -134,6 +134,7 @@
     "is-observable": "^0.2.0",
     "is-promise": "^2.1.0",
     "jest-snapshot": "^18.1.0",
+    "js-yaml": "^3.8.2",
     "last-line-stream": "^1.0.0",
     "lodash.debounce": "^4.0.3",
     "lodash.difference": "^4.3.0",

test/reporters/tap.js

@@ -34,24 +34,69 @@ test('failing test', t => {
 	const actualOutput = reporter.test({
 		title: 'failing',
 		error: {
+			name: 'AssertionError',
 			message: 'false == true',
 			operator: '==',
-			expected: true,
-			actual: false,
+			expected: 'true',
+			actual: 'false',
 			stack: ['', 'Test.fn (test.js:1:2)'].join('\n')
 		}
 	});
 
-	const expectedOutput = [
-		'# failing',
-		'not ok 1 - failing',
-		'  ---',
-		'    operator: ==',
-		'    expected: true',
-		'    actual: false',
-		'    at: Test.fn (test.js:1:2)',
-		'  ...'
-	].join('\n');
+	const expectedOutput = `# failing
+not ok 1 - failing
+  ---
+    name: AssertionError
+    message: false == true
+    operator: ==
+    actual: 'false'
+    expected: 'true'
+    at: 'Test.fn (test.js:1:2)'
+  ...`;
+
+	t.is(actualOutput, expectedOutput);
+	t.end();
+});
+
+test('multiline strings in YAML block', t => {
+	const reporter = new TapReporter();
+
+	const actualOutput = reporter.test({
+		title: 'multiline',
+		error: {
+			actual: 'hello\nworld'
+		}
+	});
+
+	const expectedOutput = `# multiline
+not ok 1 - multiline
+  ---
+    actual: |-
+      hello
+      world
+  ...`;
+
+	t.is(actualOutput, expectedOutput);
+	t.end();
+});
+
+test('strips ANSI from actual and expected values', t => {
+	const reporter = new TapReporter();
+
+	const actualOutput = reporter.test({
+		title: 'strip ansi',
+		error: {
+			actual: '\u001b[31mhello\u001b[39m',
+			expected: '\u001b[32mworld\u001b[39m'
+		}
+	});
+
+	const expectedOutput = `# strip ansi
+not ok 1 - strip ansi
+  ---
+    actual: hello
+    expected: world
+  ...`;
 
 	t.is(actualOutput, expectedOutput);
 	t.end();
@@ -66,14 +111,12 @@ test('unhandled error', t => {
 		stack: ['', 'Test.fn (test.js:1:2)'].join('\n')
 	});
 
-	const expectedOutput = [
-		'# unhandled',
-		'not ok 1 - unhandled',
-		'  ---',
-		'    name: TypeError',
-		'    at: Test.fn (test.js:1:2)',
-		'  ...'
-	].join('\n');
+	const expectedOutput = `# unhandled
+not ok 1 - unhandled
+  ---
+    name: TypeError
+    at: 'Test.fn (test.js:1:2)'
+  ...`;
 
 	t.is(actualOutput, expectedOutput);
 	t.end();