Close #125 PR: Add string support to throws.

lib/assert.js

@@ -90,6 +90,13 @@ x.throws = function (fn, err, msg) {
 	}
 
 	try {
+		if (typeof err === 'string') {
+			var errMsg = err;
+			err = function (err) {
+				return err.message === errMsg;
+			};
+		}
+
 		assert.throws(fn, err, msg);
 	} catch (err) {
 		test(false, create(err.actual, err.expected, err.operator, err.message, x.throws));

readme.md

@@ -423,7 +423,7 @@ Assert that `value` is not deep equal to `expected`.
 
 Assert that `function` throws an error or `promise` rejects.
 
-`error` can be a constructor, regex or validation function.
+`error` can be a constructor, regex, error message or validation function.
 
 ### .doesNotThrow(function|promise, [message])
 

test/test.js

@@ -240,6 +240,18 @@ test('handle throws with regex', function (t) {
 	});
 });
 
+test('handle throws with string', function (t) {
+	ava(function (a) {
+		a.plan(1);
+
+		var promise = Promise.reject(new Error('abc'));
+		a.throws(promise, 'abc');
+	}).run().then(function (a) {
+		t.false(a.assertionError);
+		t.end();
+	});
+});
+
 test('handle throws with false-positive promise', function (t) {
 	ava(function (a) {
 		a.plan(1);