Allow custom assert modules

index.js

@@ -96,3 +96,4 @@ module.exports = runner.addTest.bind(runner);
 module.exports.serial = runner.addSerialTest.bind(runner);
 module.exports.before = runner.addBeforeHook.bind(runner);
 module.exports.after = runner.addAfterHook.bind(runner);
+module.exports.setAssertModule = runner.setAssertModule.bind(runner);

lib/runner.js

@@ -24,27 +24,29 @@ function Runner(opts) {
 		before: [],
 		after: []
 	};
+
+	this._assertModule = null;
 }
 
 util.inherits(Runner, EventEmitter);
 module.exports = Runner;
 
 Runner.prototype.addTest = function (title, cb) {
 	this.stats.testCount++;
-	this.tests.concurrent.push(new Test(title, cb));
+	this.tests.concurrent.push(new Test(title, this._assertModule, cb));
 };
 
 Runner.prototype.addSerialTest = function (title, cb) {
 	this.stats.testCount++;
-	this.tests.serial.push(new Test(title, cb));
+	this.tests.serial.push(new Test(title, this._assertModule, cb));
 };
 
 Runner.prototype.addBeforeHook = function (title, cb) {
-	this.tests.before.push(new Test(title, cb));
+	this.tests.before.push(new Test(title, this._assertModule, cb));
 };
 
 Runner.prototype.addAfterHook = function (title, cb) {
-	this.tests.after.push(new Test(title, cb));
+	this.tests.after.push(new Test(title, this._assertModule, cb));
 };
 
 Runner.prototype.concurrent = function (tests) {
@@ -118,3 +120,8 @@ Runner.prototype.run = function () {
 			stats.passCount = stats.testCount - stats.failCount;
 		});
 };
+
+// Set custom assert module
+Runner.prototype.setAssertModule = function (assertModule) {
+	this._assertModule = assertModule;
+};

lib/test.js

@@ -4,14 +4,19 @@ var setImmediate = require('set-immediate-shim');
 var fnName = require('fn-name');
 var assert = require('./assert');
 
-function Test(title, fn) {
+function Test(title, assertModule, fn) {
 	if (!(this instanceof Test)) {
-		return new Test(title, fn);
+		return new Test(title, assertModule, fn);
 	}
 
-	if (typeof title !== 'string') {
-		fn = title;
-		title = null;
+	if (fn === undefined) {
+		if (typeof title === 'function') {
+			fn = title;
+			title = null;
+		} else if (typeof assertModule === 'function') {
+			fn = assertModule;
+			assertModule = null;
+		}
 	}
 
 	this.title = title || fnName(fn) || '[anonymous]';
@@ -23,6 +28,9 @@ function Test(title, fn) {
 	// store the time point before test execution
 	// to calculate the total time spent in test
 	this._timeStart = null;
+
+	// Set assert module
+	this._setAssertModule(assertModule);
 }
 
 module.exports = Test;
@@ -35,17 +43,28 @@ Test.prototype._assert = function () {
 	}
 };
 
-Object.keys(assert).forEach(function (el) {
-	Test.prototype[el] = function () {
-		this._assert();
+Test.prototype._setAssertModule = function (assertModule) {
+	var lib = assertModule || assert;
 
-		try {
-			assert[el].apply(assert, arguments);
-		} catch (err) {
-			this.assertError = err;
-		}
-	};
-});
+	if (typeof lib === 'function') {
+		setPrototype(lib.name, lib);
+	} else if (typeof lib === 'object') {
+		Object.keys(lib).forEach(function (el) {
+			setPrototype(el, lib[el]);
+		});
+	}
+
+	function setPrototype(el, method) {
+		Object.defineProperty(Test.prototype, el, {
+			get: function () {
+				this._assert();
+
+				return method;
+			},
+			configurable: true
+		});
+	}
+};
 
 Test.prototype.plan = function (count) {
 	if (typeof count !== 'number') {