diff --git a/Makefile b/Makefile
index e8b7658e8b..e1f547e175 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ TM_DEST = ~/Library/Application\ Support/TextMate/Bundles
 TM_BUNDLE = JavaScript\ mocha.tmbundle
 SRC = $(shell find lib -name "*.js" -type f | sort)
 SUPPORT = $(wildcard support/*.js)
+REPORTERS := $(shell bin/mocha --reporters | sed -e 's/ - .*//')
 
 all: mocha.js
 
@@ -33,7 +34,7 @@ lib-cov:
 
 test: test-unit
 
-test-all: test-bdd test-tdd test-qunit test-exports test-unit test-grep test-jsapi test-compilers test-glob
+test-all: test-bdd test-tdd test-qunit test-exports test-unit test-grep test-jsapi test-compilers test-glob test-reporter-output
 
 test-jsapi:
 	@node test/jsapi
@@ -104,6 +105,22 @@ test-async-only:
 test-glob:
 	@./test/acceptance/glob/glob.sh
 
+
+# The html reporter isn't supported at the command line
+TEST_REPORTERS := $(patsubst %,test-reporter-output-%,$(REPORTERS))
+TEST_REPORTERS := $(filter-out test-reporter-output-html,$(TEST_REPORTERS))
+
+.PHONY: $(REPORTERS)
+test-reporter-output: $(TEST_REPORTERS)
+test-reporter-output-%: %
+	@echo "Testing file output for reporter $<"
+	@./bin/mocha --no-color --reporter $< test/acceptance/interfaces/bdd 2>&1 > /tmp/$<.stdout
+	@./bin/mocha --no-color --reporter $< test/acceptance/interfaces/bdd -O /tmp/$<.file 2>&1 > /tmp/dot.file.stdout
+	@test -s /tmp/$<.file || \
+		(echo "ERROR: reporter $< does not support file output" && exit 1)
+	@test ! -s /tmp/$<.file.stdout || \
+		(echo "ERROR: reporter $< file output wrote to stdout" && exit 1)
+
 non-tty:
 	@./bin/mocha \
 		--reporter dot \
diff --git a/bin/_mocha b/bin/_mocha
index 7329505159..182c3db590 100755
--- a/bin/_mocha
+++ b/bin/_mocha
@@ -59,6 +59,7 @@ program
   .usage('[debug] [options] [files]')
   .option('-r, --require <name>', 'require the given module')
   .option('-R, --reporter <name>', 'specify the reporter to use', 'dot')
+  .option('-O, --output <file>', 'specify the output file', '-')
   .option('-u, --ui <name>', 'specify user-interface (bdd|tdd|exports)', 'bdd')
   .option('-g, --grep <pattern>', 'only run tests matching <pattern>')
   .option('-i, --invert', 'inverts --grep matches')
@@ -177,6 +178,10 @@ Error.stackTraceLimit = Infinity; // TODO: config
 
 mocha.reporter(program.reporter);
 
+// output
+
+mocha.output(program.output);
+
 // interface
 
 mocha.ui(program.ui);
diff --git a/lib/mocha.js b/lib/mocha.js
index cd3d303268..e52fde65df 100644
--- a/lib/mocha.js
+++ b/lib/mocha.js
@@ -27,6 +27,7 @@ exports.reporters = require('./reporters');
 exports.Runnable = require('./runnable');
 exports.Context = require('./context');
 exports.Runner = require('./runner');
+exports.output = require('./output');
 exports.Suite = require('./suite');
 exports.Hook = require('./hook');
 exports.Test = require('./test');
@@ -70,6 +71,7 @@ function Mocha(options) {
   this.ui(options.ui);
   this.bail(options.bail);
   this.reporter(options.reporter);
+  this.output(options.output);
   if (options.timeout) this.timeout(options.timeout);
   if (options.slow) this.slow(options.slow);
 }
@@ -121,6 +123,17 @@ Mocha.prototype.reporter = function(reporter){
   return this;
 };
 
+/**
+ * Set output to `output`.
+ *
+ * @param {stream|String} target output stream, filename, or "-" for stdout
+ * @api public
+ */
+
+Mocha.prototype.output = function(target) {
+    this._output = exports.output.initialize(target);
+};
+
 /**
  * Set test UI `name`, defaults to "bdd".
  *
@@ -306,11 +319,14 @@ Mocha.prototype.run = function(fn){
   var suite = this.suite;
   var options = this.options;
   var runner = new exports.Runner(suite);
-  var reporter = new this._reporter(runner);
+  var reporter = new this._reporter(runner, this._output);
   runner.ignoreLeaks = false !== options.ignoreLeaks;
   runner.asyncOnly = options.asyncOnly;
   if (options.grep) runner.grep(options.grep, options.invert);
   if (options.globals) runner.globals(options.globals);
   if (options.growl) this._growl(runner, reporter);
-  return runner.run(fn);
+  var self = this;
+  return runner.run(function(errCount) {
+      exports.output.end(errCount, fn);
+  });
 };
diff --git a/lib/output.js b/lib/output.js
new file mode 100644
index 0000000000..a6eb370d46
--- /dev/null
+++ b/lib/output.js
@@ -0,0 +1,78 @@
+var debug = require('debug')('mocha:output');
+var util = require('util');
+var fs = require('fs');
+var stream = require('stream');
+
+// Initialize in stdout mode
+var ostream = exports.ostream = process.stdout;
+
+/**
+ * Write preformatted output directly to the stream.
+ */
+exports.write = function(data) {
+    ostream.write(data);
+};
+
+
+/**
+ * Wrapper for log output.
+ */
+exports.log = function() {
+    if (ostream === process.stdout) {
+        console.log.apply(console, arguments);
+    } else {
+        ostream.write(util.format.apply(util, arguments) + "\n");
+    }
+};
+
+/**
+ * Wrapper for error output.
+ */
+exports.error = function() {
+    if (ostream === process.stdout) {
+        console.error.apply(console, arguments);
+    } else {
+        ostream.write(util.format.apply(util, arguments) + "\n");
+    }
+};
+
+/**
+ * Hook that's called when the test process is done to close the
+ * ostream ostream.
+ */
+exports.end = function(errCount, fn) {
+    if (ostream === process.stdout) {
+        // nothing to do
+        return fn(errCount);
+    }
+
+    ostream.end(function() { 
+        debug("ostream ended");
+        fn(errCount);
+
+        // Reset the ostream
+        ostream = process.stdout;
+    } );
+};
+
+/**
+ * Initialize the output module.
+ *
+ * If target is undefined or "-" then use stdout, otherwise open the
+ * target file.
+ */
+var initialize = exports.initialize = function(target) {
+    if (target === undefined) {
+        return ostream; // don't change
+    }
+
+    if (target === "-") {
+        ostream = exports.ostream = process.stdout;
+    } else if (target instanceof stream) {
+        ostream = exports.ostream = target;
+    } else {
+        ostream = exports.ostream = fs.createWriteStream(target);
+    }
+
+    return ostream;
+};
diff --git a/lib/reporters/base.js b/lib/reporters/base.js
index 215be4562c..1265bff7fa 100644
--- a/lib/reporters/base.js
+++ b/lib/reporters/base.js
@@ -5,7 +5,8 @@
 
 var tty = require('tty')
   , diff = require('diff')
-  , ms = require('../ms');
+  , ms = require('../ms')
+  , output = require('../output');
 
 /**
  * Save timer references to avoid Sinon interfering (see GH-237).
@@ -29,6 +30,12 @@ var isatty = tty.isatty(1) && tty.isatty(2);
 
 exports = module.exports = Base;
 
+/**
+ * Expose the output hooks
+ */
+exports.output = output;
+
+
 /**
  * Enable coloring by default.
  */
@@ -108,6 +115,7 @@ exports.window = {
     : 75
 };
 
+
 /**
  * Expose some basic cursor interactions
  * that are common among reporters.
@@ -144,7 +152,7 @@ exports.cursor = {
  */
 
 exports.list = function(failures){
-  console.error();
+  output.error();
   failures.forEach(function(test, i){
     // format
     var fmt = color('error title', '  %s) %s:\n')
@@ -206,7 +214,7 @@ exports.list = function(failures){
     stack = stack.slice(index ? index + 1 : index)
       .replace(/^/gm, '  ');
 
-    console.error(fmt, (i + 1), test.fullTitle(), msg, stack);
+    output.error(fmt, (i + 1), test.fullTitle(), msg, stack);
   });
 };
 
@@ -222,7 +230,7 @@ exports.list = function(failures){
  * @api public
  */
 
-function Base(runner) {
+function Base(runner, ostream) {
   var self = this
     , stats = this.stats = { suites: 0, tests: 0, passes: 0, pending: 0, failures: 0 }
     , failures = this.failures = [];
@@ -230,6 +238,9 @@ function Base(runner) {
   if (!runner) return;
   this.runner = runner;
 
+  if (!ostream) return;
+  this.ostream = ostream;
+
   runner.stats = stats;
 
   runner.on('start', function(){
@@ -288,14 +299,14 @@ Base.prototype.epilogue = function(){
   var tests;
   var fmt;
 
-  console.log();
+  output.log();
 
   // passes
   fmt = color('bright pass', ' ')
     + color('green', ' %d passing')
     + color('light', ' (%s)');
 
-  console.log(fmt,
+  output.log(fmt,
     stats.passes || 0,
     ms(stats.duration));
 
@@ -304,21 +315,21 @@ Base.prototype.epilogue = function(){
     fmt = color('pending', ' ')
       + color('pending', ' %d pending');
 
-    console.log(fmt, stats.pending);
+    output.log(fmt, stats.pending);
   }
 
   // failures
   if (stats.failures) {
     fmt = color('fail', '  %d failing');
 
-    console.error(fmt,
+    output.error(fmt,
       stats.failures);
 
     Base.list(this.failures);
-    console.error();
+    output.error();
   }
 
-  console.log();
+  output.log();
 };
 
 /**
diff --git a/lib/reporters/doc.js b/lib/reporters/doc.js
index 2e5bf57fc4..11e06a4311 100644
--- a/lib/reporters/doc.js
+++ b/lib/reporters/doc.js
@@ -4,6 +4,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , utils = require('../utils');
 
 /**
@@ -19,8 +20,8 @@ exports = module.exports = Doc;
  * @api public
  */
 
-function Doc(runner) {
-  Base.call(this, runner);
+function Doc(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -34,23 +35,23 @@ function Doc(runner) {
   runner.on('suite', function(suite){
     if (suite.root) return;
     ++indents;
-    console.log('%s<section class="suite">', indent());
+    output.log('%s<section class="suite">', indent());
     ++indents;
-    console.log('%s<h1>%s</h1>', indent(), utils.escape(suite.title));
-    console.log('%s<dl>', indent());
+    output.log('%s<h1>%s</h1>', indent(), utils.escape(suite.title));
+    output.log('%s<dl>', indent());
   });
 
   runner.on('suite end', function(suite){
     if (suite.root) return;
-    console.log('%s</dl>', indent());
+    output.log('%s</dl>', indent());
     --indents;
-    console.log('%s</section>', indent());
+    output.log('%s</section>', indent());
     --indents;
   });
 
   runner.on('pass', function(test){
-    console.log('%s  <dt>%s</dt>', indent(), utils.escape(test.title));
+    output.log('%s  <dt>%s</dt>', indent(), utils.escape(test.title));
     var code = utils.escape(utils.clean(test.fn.toString()));
-    console.log('%s  <dd><pre><code>%s</code></pre></dd>', indent(), code);
+    output.log('%s  <dd><pre><code>%s</code></pre></dd>', indent(), code);
   });
 }
diff --git a/lib/reporters/dot.js b/lib/reporters/dot.js
index 0c298ba71d..86d031ef5f 100644
--- a/lib/reporters/dot.js
+++ b/lib/reporters/dot.js
@@ -19,8 +19,8 @@ exports = module.exports = Dot;
  * @api public
  */
 
-function Dot(runner) {
-  Base.call(this, runner);
+function Dot(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -28,29 +28,29 @@ function Dot(runner) {
     , n = 0;
 
   runner.on('start', function(){
-    process.stdout.write('\n  ');
+    ostream.write('\n  ');
   });
 
   runner.on('pending', function(test){
-    process.stdout.write(color('pending', Base.symbols.dot));
+    ostream.write(color('pending', Base.symbols.dot));
   });
 
   runner.on('pass', function(test){
-    if (++n % width == 0) process.stdout.write('\n  ');
+    if (++n % width == 0) ostream.write('\n  ');
     if ('slow' == test.speed) {
-      process.stdout.write(color('bright yellow', Base.symbols.dot));
+      ostream.write(color('bright yellow', Base.symbols.dot));
     } else {
-      process.stdout.write(color(test.speed, Base.symbols.dot));
+      ostream.write(color(test.speed, Base.symbols.dot));
     }
   });
 
   runner.on('fail', function(test, err){
-    if (++n % width == 0) process.stdout.write('\n  ');
-    process.stdout.write(color('fail', Base.symbols.dot));
+    if (++n % width == 0) ostream.write('\n  ');
+    ostream.write(color('fail', Base.symbols.dot));
   });
 
   runner.on('end', function(){
-    console.log();
+    ostream.write("\n");
     self.epilogue();
   });
 }
@@ -59,4 +59,4 @@ function Dot(runner) {
  * Inherit from `Base.prototype`.
  */
 
-Dot.prototype.__proto__ = Base.prototype;
\ No newline at end of file
+Dot.prototype.__proto__ = Base.prototype;
diff --git a/lib/reporters/html-cov.js b/lib/reporters/html-cov.js
index bfb27ffdf6..dc5a67d7e9 100644
--- a/lib/reporters/html-cov.js
+++ b/lib/reporters/html-cov.js
@@ -19,17 +19,17 @@ exports = module.exports = HTMLCov;
  * @api public
  */
 
-function HTMLCov(runner) {
+function HTMLCov(runner, ostream) {
   var jade = require('jade')
     , file = __dirname + '/templates/coverage.jade'
     , str = fs.readFileSync(file, 'utf8')
     , fn = jade.compile(str, { filename: file })
     , self = this;
 
-  JSONCov.call(this, runner, false);
+  JSONCov.call(this, runner, ostream, false);
 
   runner.on('end', function(){
-    process.stdout.write(fn({
+    ostream.write(fn({
         cov: self.cov
       , coverageClass: coverageClass
     }));
@@ -48,4 +48,4 @@ function coverageClass(n) {
   if (n >= 50) return 'medium';
   if (n >= 25) return 'low';
   return 'terrible';
-}
\ No newline at end of file
+}
diff --git a/lib/reporters/html.js b/lib/reporters/html.js
index f09279be20..ce679fc01c 100644
--- a/lib/reporters/html.js
+++ b/lib/reporters/html.js
@@ -42,8 +42,8 @@ var statsTemplate = '<ul id="mocha-stats">'
  * @api public
  */
 
-function HTML(runner, root) {
-  Base.call(this, runner);
+function HTML(runner, ostream, root) {
+  Base.call(this, ostream, runner);
 
   var self = this
     , stats = this.stats
diff --git a/lib/reporters/json-cov.js b/lib/reporters/json-cov.js
index 73d0009377..77ec2b273b 100644
--- a/lib/reporters/json-cov.js
+++ b/lib/reporters/json-cov.js
@@ -19,11 +19,11 @@ exports = module.exports = JSONCov;
  * @api public
  */
 
-function JSONCov(runner, output) {
+function JSONCov(runner, ostream, output) {
   var self = this
-    , output = 1 == arguments.length ? true : output;
+    , output = 2 == arguments.length ? true : output;
 
-  Base.call(this, runner);
+  Base.call(this, runner, ostream);
 
   var tests = []
     , failures = []
@@ -49,7 +49,7 @@ function JSONCov(runner, output) {
     result.failures = failures.map(clean);
     result.passes = passes.map(clean);
     if (!output) return;
-    process.stdout.write(JSON.stringify(result, null, 2 ));
+    ostream.write(JSON.stringify(result, null, 2 ));
   });
 }
 
diff --git a/lib/reporters/json-stream.js b/lib/reporters/json-stream.js
index 7cb8fbede7..fe18eefe78 100644
--- a/lib/reporters/json-stream.js
+++ b/lib/reporters/json-stream.js
@@ -19,27 +19,27 @@ exports = module.exports = List;
  * @api public
  */
 
-function List(runner) {
-  Base.call(this, runner);
+function List(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
     , total = runner.total;
 
   runner.on('start', function(){
-    console.log(JSON.stringify(['start', { total: total }]));
+    ostream.write(JSON.stringify(['start', { total: total }]) + "\n");
   });
 
   runner.on('pass', function(test){
-    console.log(JSON.stringify(['pass', clean(test)]));
+    ostream.write(JSON.stringify(['pass', clean(test)]) + "\n");
   });
 
   runner.on('fail', function(test, err){
-    console.log(JSON.stringify(['fail', clean(test)]));
+    ostream.write(JSON.stringify(['fail', clean(test)]) + "\n");
   });
 
   runner.on('end', function(){
-    process.stdout.write(JSON.stringify(['end', self.stats]));
+    ostream.write(JSON.stringify(['end', self.stats]) + "\n");
   });
 }
 
@@ -58,4 +58,4 @@ function clean(test) {
     , fullTitle: test.fullTitle()
     , duration: test.duration
   }
-}
\ No newline at end of file
+}
diff --git a/lib/reporters/json.js b/lib/reporters/json.js
index a699f5014a..674440bf25 100644
--- a/lib/reporters/json.js
+++ b/lib/reporters/json.js
@@ -20,9 +20,9 @@ exports = module.exports = JSONReporter;
  * @api public
  */
 
-function JSONReporter(runner) {
+function JSONReporter(runner, ostream) {
   var self = this;
-  Base.call(this, runner);
+  Base.call(this, runner, ostream);
 
   var tests = []
     , failures = []
@@ -48,7 +48,7 @@ function JSONReporter(runner) {
       , passes: passes.map(clean)
     };
 
-    process.stdout.write(JSON.stringify(obj, null, 2));
+    ostream.write(JSON.stringify(obj, null, 2));
   });
 }
 
@@ -67,4 +67,4 @@ function clean(test) {
     , fullTitle: test.fullTitle()
     , duration: test.duration
   }
-}
\ No newline at end of file
+}
diff --git a/lib/reporters/landing.js b/lib/reporters/landing.js
index bf064f64b2..8ece1cd2a4 100644
--- a/lib/reporters/landing.js
+++ b/lib/reporters/landing.js
@@ -38,14 +38,13 @@ Base.colors.runway = 90;
  * @api public
  */
 
-function Landing(runner) {
-  Base.call(this, runner);
+function Landing(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
     , width = Base.window.width * .75 | 0
     , total = runner.total
-    , stream = process.stdout
     , plane = color('plane', '✈')
     , crashed = -1
     , n = 0;
@@ -56,7 +55,7 @@ function Landing(runner) {
   }
 
   runner.on('start', function(){
-    stream.write('\n  ');
+    ostream.write('\n  ');
     cursor.hide();
   });
 
@@ -73,19 +72,19 @@ function Landing(runner) {
     }
 
     // render landing strip
-    stream.write('\u001b[4F\n\n');
-    stream.write(runway());
-    stream.write('\n  ');
-    stream.write(color('runway', Array(col).join('⋅')));
-    stream.write(plane)
-    stream.write(color('runway', Array(width - col).join('⋅') + '\n'));
-    stream.write(runway());
-    stream.write('\u001b[0m');
+    ostream.write('\u001b[4F\n\n');
+    ostream.write(runway());
+    ostream.write('\n  ');
+    ostream.write(color('runway', Array(col).join('⋅')));
+    ostream.write(plane);
+    ostream.write(color('runway', Array(width - col).join('⋅') + '\n'));
+    ostream.write(runway());
+    ostream.write('\u001b[0m');
   });
 
   runner.on('end', function(){
     cursor.show();
-    console.log();
+    ostream.write("\n");
     self.epilogue();
   });
 }
@@ -94,4 +93,4 @@ function Landing(runner) {
  * Inherit from `Base.prototype`.
  */
 
-Landing.prototype.__proto__ = Base.prototype;
\ No newline at end of file
+Landing.prototype.__proto__ = Base.prototype;
diff --git a/lib/reporters/list.js b/lib/reporters/list.js
index 3328e157a8..dcae654a33 100644
--- a/lib/reporters/list.js
+++ b/lib/reporters/list.js
@@ -4,6 +4,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , cursor = Base.cursor
   , color = Base.color;
 
@@ -20,25 +21,25 @@ exports = module.exports = List;
  * @api public
  */
 
-function List(runner) {
-  Base.call(this, runner);
+function List(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
     , n = 0;
 
   runner.on('start', function(){
-    console.log();
+    output.log();
   });
 
   runner.on('test', function(test){
-    process.stdout.write(color('pass', '    ' + test.fullTitle() + ': '));
+    output.write(color('pass', '    ' + test.fullTitle() + ': '));
   });
 
   runner.on('pending', function(test){
     var fmt = color('checkmark', '  -')
       + color('pending', ' %s');
-    console.log(fmt, test.fullTitle());
+    output.log(fmt, test.fullTitle());
   });
 
   runner.on('pass', function(test){
@@ -46,12 +47,12 @@ function List(runner) {
       + color('pass', ' %s: ')
       + color(test.speed, '%dms');
     cursor.CR();
-    console.log(fmt, test.fullTitle(), test.duration);
+    output.log(fmt, test.fullTitle(), test.duration);
   });
 
   runner.on('fail', function(test, err){
     cursor.CR();
-    console.log(color('fail', '  %d) %s'), ++n, test.fullTitle());
+    output.log(color('fail', '  %d) %s'), ++n, test.fullTitle());
   });
 
   runner.on('end', self.epilogue.bind(self));
diff --git a/lib/reporters/markdown.js b/lib/reporters/markdown.js
index 6383a64248..70f20e26ac 100644
--- a/lib/reporters/markdown.js
+++ b/lib/reporters/markdown.js
@@ -18,8 +18,8 @@ exports = module.exports = Markdown;
  * @api public
  */
 
-function Markdown(runner) {
-  Base.call(this, runner);
+function Markdown(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -84,8 +84,8 @@ function Markdown(runner) {
   });
 
   runner.on('end', function(){
-    process.stdout.write('# TOC\n');
-    process.stdout.write(generateTOC(runner.suite));
-    process.stdout.write(buf);
+    ostream.write('# TOC\n');
+    ostream.write(generateTOC(runner.suite));
+    ostream.write(buf);
   });
-}
\ No newline at end of file
+}
diff --git a/lib/reporters/min.js b/lib/reporters/min.js
index 1b6117d065..c495fc0fce 100644
--- a/lib/reporters/min.js
+++ b/lib/reporters/min.js
@@ -18,14 +18,14 @@ exports = module.exports = Min;
  * @api public
  */
 
-function Min(runner) {
-  Base.call(this, runner);
+function Min(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   runner.on('start', function(){
     // clear screen
-    process.stdout.write('\u001b[2J');
+    ostream.write('\u001b[2J');
     // set cursor position
-    process.stdout.write('\u001b[1;3H');
+    ostream.write('\u001b[1;3H');
   });
 
   runner.on('end', this.epilogue.bind(this));
diff --git a/lib/reporters/nyan.js b/lib/reporters/nyan.js
index b43e2440d0..099329e409 100644
--- a/lib/reporters/nyan.js
+++ b/lib/reporters/nyan.js
@@ -3,6 +3,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , color = Base.color;
 
 /**
@@ -18,8 +19,8 @@ exports = module.exports = NyanCat;
  * @api public
  */
 
-function NyanCat(runner) {
-  Base.call(this, runner);
+function NyanCat(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -239,11 +240,11 @@ NyanCat.prototype.rainbowify = function(str){
 };
 
 /**
- * Stdout helper.
+ * Output helper.
  */
 
 function write(string) {
-  process.stdout.write(string);
+  output.write(string);
 }
 
 /**
diff --git a/lib/reporters/progress.js b/lib/reporters/progress.js
index 59536386cb..19b40549f2 100644
--- a/lib/reporters/progress.js
+++ b/lib/reporters/progress.js
@@ -27,8 +27,8 @@ Base.colors.progress = 90;
  * @api public
  */
 
-function Progress(runner, options) {
-  Base.call(this, runner);
+function Progress(runner, ostream, options) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , options = options || {}
@@ -47,7 +47,7 @@ function Progress(runner, options) {
 
   // tests started
   runner.on('start', function(){
-    console.log();
+    ostream.write("\n");
     cursor.hide();
   });
 
@@ -60,13 +60,13 @@ function Progress(runner, options) {
       , i = width - n;
 
     cursor.CR();
-    process.stdout.write('\u001b[J');
-    process.stdout.write(color('progress', '  ' + options.open));
-    process.stdout.write(Array(n).join(options.complete));
-    process.stdout.write(Array(i).join(options.incomplete));
-    process.stdout.write(color('progress', options.close));
+    ostream.write('\u001b[J');
+    ostream.write(color('progress', '  ' + options.open));
+    ostream.write(Array(n).join(options.complete));
+    ostream.write(Array(i).join(options.incomplete));
+    ostream.write(color('progress', options.close));
     if (options.verbose) {
-      process.stdout.write(color('progress', ' ' + complete + ' of ' + total));
+      ostream.write(color('progress', ' ' + complete + ' of ' + total));
     }
   });
 
@@ -74,7 +74,7 @@ function Progress(runner, options) {
   // and the failures if any
   runner.on('end', function(){
     cursor.show();
-    console.log();
+    ostream.write("\n");
     self.epilogue();
   });
 }
diff --git a/lib/reporters/spec.js b/lib/reporters/spec.js
index cd97261c12..18d491fe26 100644
--- a/lib/reporters/spec.js
+++ b/lib/reporters/spec.js
@@ -4,6 +4,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , cursor = Base.cursor
   , color = Base.color;
 
@@ -20,8 +21,8 @@ exports = module.exports = Spec;
  * @api public
  */
 
-function Spec(runner) {
-  Base.call(this, runner);
+function Spec(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -33,26 +34,26 @@ function Spec(runner) {
   }
 
   runner.on('start', function(){
-    console.log();
+    output.log();
   });
 
   runner.on('suite', function(suite){
     ++indents;
-    console.log(color('suite', '%s%s'), indent(), suite.title);
+    output.log(color('suite', '%s%s'), indent(), suite.title);
   });
 
   runner.on('suite end', function(suite){
     --indents;
-    if (1 == indents) console.log();
+    if (1 == indents) output.log();
   });
 
   runner.on('test', function(test){
-    process.stdout.write(indent() + color('pass', '  ◦ ' + test.title + ': '));
+    output.write(indent() + color('pass', '  ◦ ' + test.title + ': '));
   });
 
   runner.on('pending', function(test){
     var fmt = indent() + color('pending', '  - %s');
-    console.log(fmt, test.title);
+    output.log(fmt, test.title);
   });
 
   runner.on('pass', function(test){
@@ -61,20 +62,20 @@ function Spec(runner) {
         + color('checkmark', '  ' + Base.symbols.ok)
         + color('pass', ' %s ');
       cursor.CR();
-      console.log(fmt, test.title);
+      output.log(fmt, test.title);
     } else {
       var fmt = indent()
         + color('checkmark', '  ' + Base.symbols.ok)
         + color('pass', ' %s ')
         + color(test.speed, '(%dms)');
       cursor.CR();
-      console.log(fmt, test.title, test.duration);
+      output.log(fmt, test.title, test.duration);
     }
   });
 
   runner.on('fail', function(test, err){
     cursor.CR();
-    console.log(indent() + color('fail', '  %d) %s'), ++n, test.title);
+    output.log(indent() + color('fail', '  %d) %s'), ++n, test.title);
   });
 
   runner.on('end', self.epilogue.bind(self));
diff --git a/lib/reporters/tap.js b/lib/reporters/tap.js
index 2bcd995baa..b2043a24ff 100644
--- a/lib/reporters/tap.js
+++ b/lib/reporters/tap.js
@@ -4,6 +4,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , cursor = Base.cursor
   , color = Base.color;
 
@@ -20,8 +21,8 @@ exports = module.exports = TAP;
  * @api public
  */
 
-function TAP(runner) {
-  Base.call(this, runner);
+function TAP(runner, ostream) {
+  Base.call(this, runner, ostream);
 
   var self = this
     , stats = this.stats
@@ -31,7 +32,7 @@ function TAP(runner) {
 
   runner.on('start', function(){
     var total = runner.grepTotal(runner.suite);
-    console.log('%d..%d', 1, total);
+    output.log('%d..%d', 1, total);
   });
 
   runner.on('test end', function(){
@@ -39,24 +40,24 @@ function TAP(runner) {
   });
 
   runner.on('pending', function(test){
-    console.log('ok %d %s # SKIP -', n, title(test));
+    output.log('ok %d %s # SKIP -', n, title(test));
   });
 
   runner.on('pass', function(test){
     passes++;
-    console.log('ok %d %s', n, title(test));
+    output.log('ok %d %s', n, title(test));
   });
 
   runner.on('fail', function(test, err){
     failures++;
-    console.log('not ok %d %s', n, title(test));
-    if (err.stack) console.log(err.stack.replace(/^/gm, '  '));
+    output.log('not ok %d %s', n, title(test));
+    if (err.stack) output.log(err.stack.replace(/^/gm, '  '));
   });
 
   runner.on('end', function(){
-    console.log('# tests ' + (passes + failures));
-    console.log('# pass ' + passes);
-    console.log('# fail ' + failures);
+    output.log('# tests ' + (passes + failures));
+    output.log('# pass ' + passes);
+    output.log('# fail ' + failures);
   });
 }
 
diff --git a/lib/reporters/teamcity.js b/lib/reporters/teamcity.js
index 032eea7d2b..1572e3efa5 100644
--- a/lib/reporters/teamcity.js
+++ b/lib/reporters/teamcity.js
@@ -3,7 +3,8 @@
  * Module dependencies.
  */
 
-var Base = require('./base');
+var Base = require('./base')
+  , output = Base.output;
 
 /**
  * Expose `Teamcity`.
@@ -18,32 +19,32 @@ exports = module.exports = Teamcity;
  * @api public
  */
 
-function Teamcity(runner) {
-  Base.call(this, runner);
+function Teamcity(runner, ostream) {
+  Base.call(this, runner, ostream);
   var stats = this.stats;
 
   runner.on('start', function() {
-    console.log("##teamcity[testSuiteStarted name='mocha.suite']");
+    output.log("##teamcity[testSuiteStarted name='mocha.suite']");
   });
 
   runner.on('test', function(test) {
-    console.log("##teamcity[testStarted name='" + escape(test.fullTitle()) + "']");
+    output.log("##teamcity[testStarted name='" + escape(test.fullTitle()) + "']");
   });
 
   runner.on('fail', function(test, err) {
-    console.log("##teamcity[testFailed name='" + escape(test.fullTitle()) + "' message='" + escape(err.message) + "']");
+    output.log("##teamcity[testFailed name='" + escape(test.fullTitle()) + "' message='" + escape(err.message) + "']");
   });
 
   runner.on('pending', function(test) {
-    console.log("##teamcity[testIgnored name='" + escape(test.fullTitle()) + "' message='pending']");
+    output.log("##teamcity[testIgnored name='" + escape(test.fullTitle()) + "' message='pending']");
   });
 
   runner.on('test end', function(test) {
-    console.log("##teamcity[testFinished name='" + escape(test.fullTitle()) + "' duration='" + test.duration + "']");
+    output.log("##teamcity[testFinished name='" + escape(test.fullTitle()) + "' duration='" + test.duration + "']");
   });
 
   runner.on('end', function() {
-    console.log("##teamcity[testSuiteFinished name='mocha.suite' duration='" + stats.duration + "']");
+    output.log("##teamcity[testSuiteFinished name='mocha.suite' duration='" + stats.duration + "']");
   });
 }
 
diff --git a/lib/reporters/xunit.js b/lib/reporters/xunit.js
index 702aa3cee2..6871e03e09 100644
--- a/lib/reporters/xunit.js
+++ b/lib/reporters/xunit.js
@@ -4,6 +4,7 @@
  */
 
 var Base = require('./base')
+  , output = Base.output
   , utils = require('../utils')
   , escape = utils.escape;
 
@@ -30,8 +31,8 @@ exports = module.exports = XUnit;
  * @api public
  */
 
-function XUnit(runner) {
-  Base.call(this, runner);
+function XUnit(runner, ostream) {
+  Base.call(this, runner, ostream);
   var stats = this.stats
     , tests = []
     , self = this;
@@ -45,7 +46,7 @@ function XUnit(runner) {
   });
 
   runner.on('end', function(){
-    console.log(tag('testsuite', {
+    output.log(tag('testsuite', {
         name: 'Mocha Tests'
       , tests: stats.tests
       , failures: stats.failures
@@ -56,7 +57,7 @@ function XUnit(runner) {
     }, false));
 
     tests.forEach(test);
-    console.log('</testsuite>');
+    output.log('</testsuite>');
   });
 }
 
@@ -80,11 +81,11 @@ function test(test) {
   if ('failed' == test.state) {
     var err = test.err;
     attrs.message = escape(err.message);
-    console.log(tag('testcase', attrs, false, tag('failure', attrs, false, cdata(err.stack))));
+    output.log(tag('testcase', attrs, false, tag('failure', attrs, false, cdata(err.stack))));
   } else if (test.pending) {
-    console.log(tag('testcase', attrs, false, tag('skipped', {}, true)));
+    output.log(tag('testcase', attrs, false, tag('skipped', {}, true)));
   } else {
-    console.log(tag('testcase', attrs, true) );
+    output.log(tag('testcase', attrs, true) );
   }
 }
 
diff --git a/mocha.js b/mocha.js
index 2b35a88302..ee972135d6 100644
--- a/mocha.js
+++ b/mocha.js
@@ -672,8 +672,14 @@ exports.isatty = function(){
 };
 
 exports.getWindowSize = function(){
-  return [window.innerHeight, window.innerWidth];
+  if ('innerHeight' in global) {
+    return [global.innerHeight, global.innerWidth];
+  } else {
+    // In a Web Worker, the DOM Window is not available.
+    return [640, 480];
+  }
 };
+
 }); // module: browser/tty.js
 
 require.register("context.js", function(module, exports, require){
@@ -1225,6 +1231,17 @@ module.exports = function(suite){
       return suite;
     };
 
+    /**
+     * Pending suite.
+     */
+    context.suite.skip = function(title, fn) {
+      var suite = Suite.create(suites[0], title);
+      suite.pending = true;
+      suites.unshift(suite);
+      fn.call(suite);
+      suites.shift();
+    };
+
     /**
      * Exclusive test-case.
      */
@@ -1241,8 +1258,10 @@ module.exports = function(suite){
      */
 
     context.test = function(title, fn){
+      var suite = suites[0];
+      if (suite.pending) var fn = null;
       var test = new Test(title, fn);
-      suites[0].addTest(test);
+      suite.addTest(test);
       return test;
     };
 
@@ -1297,6 +1316,7 @@ exports.reporters = require('./reporters');
 exports.Runnable = require('./runnable');
 exports.Context = require('./context');
 exports.Runner = require('./runner');
+exports.output = require('./output');
 exports.Suite = require('./suite');
 exports.Hook = require('./hook');
 exports.Test = require('./test');
@@ -1340,6 +1360,7 @@ function Mocha(options) {
   this.ui(options.ui);
   this.bail(options.bail);
   this.reporter(options.reporter);
+  this.output(options.output);
   if (options.timeout) this.timeout(options.timeout);
   if (options.slow) this.slow(options.slow);
 }
@@ -1391,6 +1412,19 @@ Mocha.prototype.reporter = function(reporter){
   return this;
 };
 
+/**
+ * Set output to `output`, defaults to "-".
+ *
+ * @param {String} target file name
+ * @api public
+ */
+
+Mocha.prototype.output = function(target) {
+    if (target !== undefined) {
+        exports.output.initialize(target);
+    }
+};
+
 /**
  * Set test UI `name`, defaults to "bdd".
  *
@@ -1582,7 +1616,10 @@ Mocha.prototype.run = function(fn){
   if (options.grep) runner.grep(options.grep, options.invert);
   if (options.globals) runner.globals(options.globals);
   if (options.growl) this._growl(runner, reporter);
-  return runner.run(fn);
+  var self = this;
+  return runner.run(function(errCount) {
+      exports.output.end(errCount, fn);
+  });
 };
 
 }); // module: mocha.js
@@ -1671,6 +1708,74 @@ function format(ms) {
 }
 }); // module: ms.js
 
+require.register("output.js", function(module, exports, require){
+var debug = require('browser/debug')('mocha:output');
+var fs = require('browser/fs');
+
+// Initialize to be in stdout mode
+var stream = process.stdout;
+var _console = console;
+
+/**
+ * Write preformatted output directly to the stream.
+ */
+var write = exports.write = function(data) {
+    stream.write(data);
+};
+
+
+/**
+ * Wrapper for console.log output.
+ */
+var log = exports.log = function() {
+    _console.log.apply(_console, arguments);
+};
+
+/**
+ * Wrapper for console.error output.
+ */
+var error = exports.error = function() {
+    _console.error.apply(_console, arguments);
+};
+
+/**
+ * Hook that's called when the test process is done to close the
+ * output stream.
+ */
+var end = exports.end = function(errCount, fn) {
+    if (stream === process.stdout) {
+        // nothing to do
+        return fn(errCount);
+    }
+
+    stream.end(function() { 
+        debug("stream ended");
+        fn(errCount);
+
+        // Reset the stream
+        stream = process.stdout;
+    } );
+};
+
+/**
+ * Initialize the output layer.
+ *
+ * If target is undefined or "-" then use stdout, otherwise open the
+ * target file.
+ */
+var initialize = exports.initialize = function(target) {
+    if (target === undefined || target === "-") {
+        return; // nothing to do - stay in stdout mode
+    }
+
+    stream = fs.createWriteStream(target);
+    _console = new console.Console(stream);
+};
+
+
+
+}); // module: output.js
+
 require.register("reporters/base.js", function(module, exports, require){
 
 /**
@@ -1679,7 +1784,8 @@ require.register("reporters/base.js", function(module, exports, require){
 
 var tty = require('browser/tty')
   , diff = require('browser/diff')
-  , ms = require('../ms');
+  , ms = require('../ms')
+  , output = require('../output');
 
 /**
  * Save timer references to avoid Sinon interfering (see GH-237).
@@ -1703,6 +1809,12 @@ var isatty = tty.isatty(1) && tty.isatty(2);
 
 exports = module.exports = Base;
 
+/**
+ * Expose the output hooks
+ */
+exports.output = output;
+
+
 /**
  * Enable coloring by default.
  */
@@ -1782,6 +1894,7 @@ exports.window = {
     : 75
 };
 
+
 /**
  * Expose some basic cursor interactions
  * that are common among reporters.
@@ -1818,7 +1931,7 @@ exports.cursor = {
  */
 
 exports.list = function(failures){
-  console.error();
+  output.error();
   failures.forEach(function(test, i){
     // format
     var fmt = color('error title', '  %s) %s:\n')
@@ -1835,6 +1948,11 @@ exports.list = function(failures){
       , expected = err.expected
       , escape = true;
 
+    // uncaught
+    if (err.uncaught) {
+      msg = 'Uncaught ' + msg;
+    }
+
     // explicitly show diff
     if (err.showDiff) {
       escape = false;
@@ -1875,7 +1993,7 @@ exports.list = function(failures){
     stack = stack.slice(index ? index + 1 : index)
       .replace(/^/gm, '  ');
 
-    console.error(fmt, (i + 1), test.fullTitle(), msg, stack);
+    output.error(fmt, (i + 1), test.fullTitle(), msg, stack);
   });
 };
 
@@ -1953,51 +2071,41 @@ function Base(runner) {
  */
 
 Base.prototype.epilogue = function(){
-  var stats = this.stats
-    , fmt
-    , tests;
-
-  console.log();
-
-  function pluralize(n) {
-    return 1 == n ? 'test' : 'tests';
-  }
-
-  // failure
-  if (stats.failures) {
-    fmt = color('bright fail', '  ' + exports.symbols.err)
-      + color('fail', ' %d of %d %s failed')
-      + color('light', ':')
+  var stats = this.stats;
+  var tests;
+  var fmt;
 
-    console.error(fmt,
-      stats.failures,
-      this.runner.total,
-      pluralize(this.runner.total));
+  output.log();
 
-    Base.list(this.failures);
-    console.error();
-    return;
-  }
-
-  // pass
+  // passes
   fmt = color('bright pass', ' ')
-    + color('green', ' %d %s complete')
+    + color('green', ' %d passing')
     + color('light', ' (%s)');
 
-  console.log(fmt,
-    stats.tests || 0,
-    pluralize(stats.tests),
+  output.log(fmt,
+    stats.passes || 0,
     ms(stats.duration));
 
   // pending
   if (stats.pending) {
     fmt = color('pending', ' ')
-      + color('pending', ' %d %s pending');
+      + color('pending', ' %d pending');
+
+    output.log(fmt, stats.pending);
+  }
 
-    console.log(fmt, stats.pending, pluralize(stats.pending));
+  // failures
+  if (stats.failures) {
+    fmt = color('fail', '  %d failing');
+
+    output.error(fmt,
+      stats.failures);
+
+    Base.list(this.failures);
+    output.error();
   }
 
-  console.log();
+  output.log();
 };
 
 /**
@@ -2120,6 +2228,7 @@ require.register("reporters/dot.js", function(module, exports, require){
  */
 
 var Base = require('./base')
+  , output = Base.output
   , color = Base.color;
 
 /**
@@ -2144,29 +2253,29 @@ function Dot(runner) {
     , n = 0;
 
   runner.on('start', function(){
-    process.stdout.write('\n  ');
+    output.write('\n  ');
   });
 
   runner.on('pending', function(test){
-    process.stdout.write(color('pending', Base.symbols.dot));
+    output.write(color('pending', Base.symbols.dot));
   });
 
   runner.on('pass', function(test){
-    if (++n % width == 0) process.stdout.write('\n  ');
+    if (++n % width == 0) output.write('\n  ');
     if ('slow' == test.speed) {
-      process.stdout.write(color('bright yellow', Base.symbols.dot));
+      output.write(color('bright yellow', Base.symbols.dot));
     } else {
-      process.stdout.write(color(test.speed, Base.symbols.dot));
+      output.write(color(test.speed, Base.symbols.dot));
     }
   });
 
   runner.on('fail', function(test, err){
-    if (++n % width == 0) process.stdout.write('\n  ');
-    process.stdout.write(color('fail', Base.symbols.dot));
+    if (++n % width == 0) output.write('\n  ');
+    output.write(color('fail', Base.symbols.dot));
   });
 
   runner.on('end', function(){
-    console.log();
+    output.writeln();
     self.epilogue();
   });
 }
@@ -2180,6 +2289,7 @@ F.prototype = Base.prototype;
 Dot.prototype = new F;
 Dot.prototype.constructor = Dot;
 
+
 }); // module: reporters/dot.js
 
 require.register("reporters/html-cov.js", function(module, exports, require){
@@ -3729,6 +3839,7 @@ require.register("reporters/xunit.js", function(module, exports, require){
  */
 
 var Base = require('./base')
+  , output = Base.output
   , utils = require('../utils')
   , escape = utils.escape;
 
@@ -3770,7 +3881,7 @@ function XUnit(runner) {
   });
 
   runner.on('end', function(){
-    console.log(tag('testsuite', {
+    output.writeln(tag('testsuite', {
         name: 'Mocha Tests'
       , tests: stats.tests
       , failures: stats.failures
@@ -3781,7 +3892,7 @@ function XUnit(runner) {
     }, false));
 
     tests.forEach(test);
-    console.log('</testsuite>');
+    output.writeln('</testsuite>');
   });
 }
 
@@ -3809,11 +3920,11 @@ function test(test) {
   if ('failed' == test.state) {
     var err = test.err;
     attrs.message = escape(err.message);
-    console.log(tag('testcase', attrs, false, tag('failure', attrs, false, cdata(err.stack))));
+    output.writeln(tag('testcase', attrs, false, tag('failure', attrs, false, cdata(err.stack))));
   } else if (test.pending) {
-    console.log(tag('testcase', attrs, false, tag('skipped', {}, true)));
+    output.writeln(tag('testcase', attrs, false, tag('skipped', {}, true)));
   } else {
-    console.log(tag('testcase', attrs, true) );
+    output.writeln(tag('testcase', attrs, true) );
   }
 }
 
@@ -3983,16 +4094,14 @@ Runnable.prototype.inspect = function(){
  */
 
 Runnable.prototype.resetTimeout = function(){
-  var self = this
-    , ms = this.timeout();
+  var self = this;
+  var ms = this.timeout() || 1e9;
 
   this.clearTimeout();
-  if (ms) {
-    this.timer = setTimeout(function(){
-      self.callback(new Error('timeout of ' + ms + 'ms exceeded'));
-      self.timedOut = true;
-    }, ms);
-  }
+  this.timer = setTimeout(function(){
+    self.callback(new Error('timeout of ' + ms + 'ms exceeded'));
+    self.timedOut = true;
+  }, ms);
 };
 
 /**
@@ -4073,7 +4182,6 @@ Runnable.prototype.run = function(fn){
 }); // module: runnable.js
 
 require.register("runner.js", function(module, exports, require){
-
 /**
  * Module dependencies.
  */
@@ -4119,6 +4227,7 @@ module.exports = Runner;
  *   - `hook end`  (hook) hook complete
  *   - `pass`  (test) test passed
  *   - `fail`  (test, err) test failed
+ *   - `pending`  (test) test pending
  *
  * @api public
  */
@@ -4311,6 +4420,7 @@ Runner.prototype.hook = function(name, fn){
   function next(i) {
     var hook = hooks[i];
     if (!hook) return fn();
+    if (self.failures && suite.bail()) return fn();
     self.currentRunnable = hook;
 
     self.emit('hook', hook);
@@ -5252,16 +5362,18 @@ exports.highlightTags = function(name) {
 };
 
 }); // module: utils.js
+// The global object is "self" in Web Workers.
+global = (function() { return this; })();
 
 /**
  * Save timer references to avoid Sinon interfering (see GH-237).
  */
 
-var Date = window.Date;
-var setTimeout = window.setTimeout;
-var setInterval = window.setInterval;
-var clearTimeout = window.clearTimeout;
-var clearInterval = window.clearInterval;
+var Date = global.Date;
+var setTimeout = global.setTimeout;
+var setInterval = global.setInterval;
+var clearTimeout = global.clearTimeout;
+var clearInterval = global.clearInterval;
 
 /**
  * Node shims.
@@ -5275,7 +5387,6 @@ var clearInterval = window.clearInterval;
 var process = {};
 process.exit = function(status){};
 process.stdout = {};
-global = window;
 
 /**
  * Remove uncaughtException listener.
@@ -5283,7 +5394,7 @@ global = window;
 
 process.removeListener = function(e){
   if ('uncaughtException' == e) {
-    window.onerror = null;
+    global.onerror = function() {};
   }
 };
 
@@ -5293,7 +5404,7 @@ process.removeListener = function(e){
 
 process.on = function(e, fn){
   if ('uncaughtException' == e) {
-    window.onerror = function(err, url, line){
+    global.onerror = function(err, url, line){
       fn(new Error(err + ' (' + url + ':' + line + ')'));
     };
   }
@@ -5303,8 +5414,8 @@ process.on = function(e, fn){
  * Expose mocha.
  */
 
-var Mocha = window.Mocha = require('mocha'),
-    mocha = window.mocha = new Mocha({ reporter: 'html' });
+var Mocha = global.Mocha = require('mocha'),
+    mocha = global.mocha = new Mocha({ reporter: 'html' });
 
 var immediateQueue = []
   , immediateTimeout;
@@ -5339,7 +5450,7 @@ Mocha.Runner.immediately = function(callback) {
 
 mocha.ui = function(ui){
   Mocha.prototype.ui.call(this, ui);
-  this.suite.emit('pre-require', window, null, this);
+  this.suite.emit('pre-require', global, null, this);
   return this;
 };
 
@@ -5361,12 +5472,15 @@ mocha.run = function(fn){
   var options = mocha.options;
   mocha.globals('location');
 
-  var query = Mocha.utils.parseQuery(window.location.search || '');
+  var query = Mocha.utils.parseQuery(global.location.search || '');
   if (query.grep) mocha.grep(query.grep);
   if (query.invert) mocha.invert();
 
   return Mocha.prototype.run.call(mocha, function(){
-    Mocha.utils.highlightTags('code');
+    // The DOM Document is not available in Web Workers.
+    if (global.document) {
+      Mocha.utils.highlightTags('code');
+    }
     if (fn) fn();
   });
 };