Make TAP reporter TAP13-capable (mochajs#3552)

* Refactored code to use `TAPProducer` objects to write output.
* Added TAP specification 13 output producer.
  * Version line
  * Errors and stacktraces inside YAML blocks
* Added TAP specification 12 output producer [default].
* Added `reporterOptions.tapVersion` to target TAP producer.
* Refactored to make use of `runner.stats`
* Refactored to use `process.stdout` stream exclusively.
* Updated to test against both specifications and incorporate work from PR mochajs#3528.
* Added integration tests for specification conformance.

lib/reporters/tap.js

@@ -6,7 +6,10 @@
  * Module dependencies.
  */
 
+var util = require('util');
 var Base = require('./base');
+var inherits = require('../utils').inherits;
+var sprintf = util.format;
 
 /**
  * Expose `TAP`.
@@ -15,65 +18,268 @@ var Base = require('./base');
 exports = module.exports = TAP;
 
 /**
- * Initialize a new `TAP` reporter.
+ * Constructs a new TAP reporter with runner instance and reporter options.
  *
  * @public
  * @class
- * @memberof Mocha.reporters
  * @extends Mocha.reporters.Base
- * @api public
- * @param {Runner} runner
+ * @memberof Mocha.reporters
+ * @param {Runner} runner - Instance triggers reporter actions.
+ * @param {Object} [options] - runner options
  */
-function TAP(runner) {
-  Base.call(this, runner);
+function TAP(runner, options) {
+  Base.call(this, runner, options);
 
+  var self = this;
   var n = 1;
-  var passes = 0;
-  var failures = 0;
 
-  runner.on('start', function() {
-    var total = runner.grepTotal(runner.suite);
-    console.log('%d..%d', 1, total);
+  var tapVersion = '12';
+  if (options && options.reporterOptions) {
+    if (options.reporterOptions.tapVersion) {
+      tapVersion = options.reporterOptions.tapVersion.toString();
+    }
+  }
+
+  this._producer = createProducer(tapVersion);
+
+  runner.once('start', function() {
+    var ntests = runner.grepTotal(runner.suite);
+    self._producer.writeVersion();
+    self._producer.writePlan(ntests);
   });
 
   runner.on('test end', function() {
     ++n;
   });
 
   runner.on('pending', function(test) {
-    console.log('ok %d %s # SKIP -', n, title(test));
+    self._producer.writePending(n, test);
   });
 
   runner.on('pass', function(test) {
-    passes++;
-    console.log('ok %d %s', n, title(test));
+    self._producer.writePass(n, test);
   });
 
   runner.on('fail', function(test, err) {
-    failures++;
-    console.log('not ok %d %s', n, title(test));
-    if (err.message) {
-      console.log(err.message.replace(/^/gm, '  '));
-    }
-    if (err.stack) {
-      console.log(err.stack.replace(/^/gm, '  '));
-    }
+    self._producer.writeFail(n, test, err);
   });
 
   runner.once('end', function() {
-    console.log('# tests ' + (passes + failures));
-    console.log('# pass ' + passes);
-    console.log('# fail ' + failures);
+    self._producer.writeEpilogue(runner.stats);
   });
 }
 
 /**
- * Return a TAP-safe title of `test`
+ * Inherit from `Base.prototype`.
+ */
+inherits(TAP, Base);
+
+/**
+ * Returns a TAP-safe title of `test`.
  *
- * @api private
- * @param {Object} test
- * @return {String}
+ * @private
+ * @param {Test} test - Test instance.
+ * @return {String} title with any hash character removed
  */
 function title(test) {
   return test.fullTitle().replace(/#/g, '');
 }
+
+/**
+ * Writes newline-terminated formatted string to reporter output stream.
+ *
+ * @private
+ * @param {string} format - `printf`-like format string
+ * @param {...*} [varArgs] - Format string arguments
+ */
+function println(format, varArgs) {
+  var vargs = Array.from(arguments);
+  vargs[0] += '\n';
+  process.stdout.write(sprintf.apply(null, vargs));
+}
+
+/**
+ * Returns a `tapVersion`-appropriate TAP producer instance, if possible.
+ *
+ * @private
+ * @param {string} tapVersion - Version of TAP specification to produce.
+ * @returns {TAPProducer} specification-appropriate instance
+ * @throws {Error} if specification version has no associated producer.
+ */
+function createProducer(tapVersion) {
+  var producers = {
+    '12': new TAP12Producer(),
+    '13': new TAP13Producer()
+  };
+  var producer = producers[tapVersion];
+
+  if (!producer) {
+    throw new Error(
+      'invalid or unsupported TAP version: ' + JSON.stringify(tapVersion)
+    );
+  }
+
+  return producer;
+}
+
+/**
+ * @summary
+ * Constructs a new TAPProducer.
+ *
+ * @description
+ * <em>Only</em> to be used as an abstract base class.
+ *
+ * @private
+ * @constructor
+ */
+function TAPProducer() {}
+
+/**
+ * Writes the TAP version to reporter output stream.
+ *
+ * @abstract
+ */
+TAPProducer.prototype.writeVersion = function() {};
+
+/**
+ * Writes the plan to reporter output stream.
+ *
+ * @abstract
+ * @param {number} ntests - Number of tests that are planned to run.
+ */
+TAPProducer.prototype.writePlan = function(ntests) {
+  println('%d..%d', 1, ntests);
+};
+
+/**
+ * Writes that test passed to reporter output stream.
+ *
+ * @abstract
+ * @param {number} n - Index of test that passed.
+ * @param {Test} test - Instance containing test information.
+ */
+TAPProducer.prototype.writePass = function(n, test) {
+  println('ok %d %s', n, title(test));
+};
+
+/**
+ * Writes that test was skipped to reporter output stream.
+ *
+ * @abstract
+ * @param {number} n - Index of test that was skipped.
+ * @param {Test} test - Instance containing test information.
+ */
+TAPProducer.prototype.writePending = function(n, test) {
+  println('ok %d %s # SKIP -', n, title(test));
+};
+
+/**
+ * Writes that test failed to reporter output stream.
+ *
+ * @abstract
+ * @param {number} n - Index of test that failed.
+ * @param {Test} test - Instance containing test information.
+ * @param {Error} err - Reason the test failed.
+ */
+TAPProducer.prototype.writeFail = function(n, test, err) {
+  println('not ok %d %s', n, title(test));
+};
+
+/**
+ * Writes the summary epilogue to reporter output stream.
+ *
+ * @abstract
+ * @param {Object} stats - Object containing run statistics.
+ */
+TAPProducer.prototype.writeEpilogue = function(stats) {
+  // :TBD: Why is this not counting pending tests?
+  println('# tests ' + (stats.passes + stats.failures));
+  println('# pass ' + stats.passes);
+  // :TBD: Why are we not showing pending results?
+  println('# fail ' + stats.failures);
+};
+
+/**
+ * @summary
+ * Constructs a new TAP12Producer.
+ *
+ * @description
+ * Produces output conforming to the TAP12 specification.
+ *
+ * @private
+ * @constructor
+ * @extends TAPProducer
+ * @see {@link https://testanything.org/tap-specification.html|Specification}
+ */
+function TAP12Producer() {
+  /**
+   * Writes that test failed to reporter output stream, with error formatting.
+   * @override
+   */
+  this.writeFail = function(n, test, err) {
+    TAPProducer.prototype.writeFail.call(this, n, test, err);
+    if (err.message) {
+      println(err.message.replace(/^/gm, '  '));
+    }
+    if (err.stack) {
+      println(err.stack.replace(/^/gm, '  '));
+    }
+  };
+}
+
+/**
+ * Inherit from `TAPProducer.prototype`.
+ */
+inherits(TAP12Producer, TAPProducer);
+
+/**
+ * @summary
+ * Constructs a new TAP13Producer.
+ *
+ * @description
+ * Produces output conforming to the TAP13 specification.
+ *
+ * @private
+ * @constructor
+ * @extends TAPProducer
+ * @see {@link https://testanything.org/tap-version-13-specification.html|Specification}
+ */
+function TAP13Producer() {
+  /**
+   * Writes the TAP version to reporter output stream.
+   * @override
+   */
+  this.writeVersion = function() {
+    println('TAP version 13');
+  };
+
+  /**
+   * Writes that test failed to reporter output stream, with error formatting.
+   * @override
+   */
+  this.writeFail = function(n, test, err) {
+    TAPProducer.prototype.writeFail.call(this, n, test, err);
+    var emitYamlBlock = err.message != null || err.stack != null;
+    if (emitYamlBlock) {
+      println(indent(1) + '---');
+      if (err.message) {
+        println(indent(2) + 'message: |-');
+        println(err.message.replace(/^/gm, indent(3)));
+      }
+      if (err.stack) {
+        println(indent(2) + 'stack: |-');
+        println(err.stack.replace(/^/gm, indent(3)));
+      }
+      println(indent(1) + '...');
+    }
+  };
+
+  function indent(level) {
+    return Array(level + 1).join('  ');
+  }
+}
+
+/**
+ * Inherit from `TAPProducer.prototype`.
+ */
+inherits(TAP13Producer, TAPProducer);

test/integration/fixtures/reporters.fixture.js

@@ -0,0 +1,63 @@
+'use strict';
+
+/**
+ * This file generates a wide range of output to test reporter functionality.
+ */
+
+describe('Animals', function() {
+
+  it('should consume organic material', function(done) { done(); });
+  it('should breathe oxygen', function(done) {
+    // we're a jellyfish
+    var actualBreathe = 'nothing';
+    var expectedBreathe = 'oxygen';
+    expect(actualBreathe, 'to equal', expectedBreathe);
+    done();
+  });
+  it('should be able to move', function(done) { done(); });
+  it('should reproduce sexually', function(done) { done(); });
+  it('should grow from a hollow sphere of cells', function(done) { done(); });
+
+  describe('Vertebrates', function() {
+    describe('Mammals', function() {
+      it('should give birth to live young', function(done) {
+        var expectedMammal = {
+          consumesMaterial: 'organic',
+          breathe: 'oxygen',
+          reproduction: {
+            type: 'sexually',
+            spawnType: 'live',
+          }
+        };
+        var platypus = JSON.parse(JSON.stringify(expectedMammal));
+        platypus['reproduction']['spawnType'] = 'hard-shelled egg';
+
+        expect(platypus, 'to equal', expectedMammal);
+        done();
+      });
+
+      describe('Blue Whale', function() {
+        it('should be the largest of all mammals', function(done) { done(); });
+        it('should have a body in some shade of blue', function(done) {
+          var bodyColor = 'blueish_grey';
+          var shadesOfBlue = ['cyan', 'light_blue', 'blue', 'indigo'];
+          expect(bodyColor, 'to be one of', shadesOfBlue);
+
+          done();
+        });
+      });
+    });
+    describe('Birds', function() {
+      it('should have feathers', function(done) { done(); });
+      it('should lay hard-shelled eggs', function(done) { done(); });
+    });
+  });
+
+  describe('Tardigrades', function() {
+    it('should answer to "water bear"', function(done) { done(); });
+    it('should be able to survive global mass extinction events', function(done) {
+      throw new Error("How do we even test for this without causing one?")
+      done();
+    });
+  });
+});