 		}
 	}
 
-	func test_ShouldPerforlBlockAfterInvalidDelay() {
+	func test_ShouldPerformBlockAfterInvalidDelay() {
 		let startDate = NSDate()
 		let expectation = expectationWithDescription("execute block after delay")
 		self.performBlockAfterDelay(-2) {
+			XCTAssert(NSThread.isMainThread() == true)
 			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(3) == false)
 			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(2) == false)
 			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(1) == false)

		}
	}

	func test_ShouldPerforlBlockAfterZeroDelay() {
		let startDate = NSDate()
		let expectation = expectationWithDescription("execute block after delay")
		self.performBlockAfterDelay(0) {
			XCTAssert(startDate.stringValue() == NSDate().stringValue())
			expectation.fulfill()
		}

		let startDate = NSDate()
		let expectation = expectationWithDescription("execute block after delay")
		self.performBlockAfterDelay(2) {
			XCTAssert(NSThread.isMainThread() == true)
			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(3) == false)
			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(2) == true)
			XCTAssert(startDate.isOlderOrEqualThanSecondInterval(1) == true)
