How to unit test throwing functions in Swift?

Question

How to test wether a function in Swift 2.0 throws or not? How to assert that the correct ErrorType is thrown?

Answer 1

Swift 4.1 Error throwing Test for associated values

enum ParseError: Error, Equatable {
    case unexpectedArgument(String)
}

func testWithNoSchemaButWithOneArgument() {
    XCTAssertThrowsError(try Args(withSchema: "", andArguments: ["-x"])) { error in
        XCTAssertEqual(error as? ParseError, ParseError.unexpectedArgument("Argument(s) -x unexpected."))
    }
}