Throw testing support for XCTest

use-sample.swift

import XCTest  
  
enum SampleError: ErrorType {case ItCouldBeWorse, ThisIsBad, ThisIsReallyBad}  
  
func sampleThrowingFunc(v: Int) throws -> Int  
{  
    if (v == 0) {throw SampleError.ItCouldBeWorse}  
    if (v < 0) {throw SampleError.ThisIsBad}  
    if (v > 255) {throw SampleError.ThisIsReallyBad}  
    return v  
}  
  
  
class SwiftErrorTestingSample: XCTestCase  
{  
    func test_Examples()  
    {  
        let a = -35  
         
        XCTempAssertThrowsError() {try sampleThrowingFunc(a)}  
         
        XCTempAssertThrowsSpecificError(SampleError.ThisIsBad) {try sampleThrowingFunc(a)}  
         
        XCTempAssertNoThrowError("customized failure message") {  
             
            let x = Int(arc4random() % 256)  
            let y = try sampleThrowingFunc(x)  
         
            XCTAssert(x == y, "")  
        }  
         
        XCTempAssertNoThrowSpecificError(SampleError.ThisIsReallyBad) {try sampleThrowingFunc(a)}  
    }  
  
}  

XCTAssertSwiftError.swift

//
//  XCTAssertSwiftError.swift
//
//  Created by LCS on 6/17/15.
//  Released into public domain; use at your own risk.
//

import XCTest

func XCTempAssertThrowsError(message: String = "", file: String = __FILE__, line: UInt = __LINE__, _ block: () throws -> ())
{
    do
    {
        try block()
        
        let msg = (message == "") ? "Tested block did not throw error as expected." : message
        XCTFail(msg, file: file, line: line)
    }
    catch {}
}


func XCTempAssertThrowsSpecificError(kind: ErrorType, _ message: String = "", file: String = __FILE__, line: UInt = __LINE__, _ block: () throws -> ())
{
    do
    {
        try block()
        
        let msg = (message == "") ? "Tested block did not throw expected \(kind) error." : message
        XCTFail(msg, file: file, line: line)
    }
    catch let error as NSError
    {
        let expected = kind as NSError
        if ((error.domain != expected.domain) || (error.code != expected.code))
        {
            let msg = (message == "") ? "Tested block threw \(error), not expected \(kind) error." : message
            XCTFail(msg, file: file, line: line)
        }
    }
}


func XCTempAssertNoThrowError(message: String = "", file: String = __FILE__, line: UInt = __LINE__, _ block: () throws -> ())
{
    do {try block()}
    catch
    {
        let msg = (message == "") ? "Tested block threw unexpected error." : message
        XCTFail(msg, file: file, line: line)
    }
}


func XCTempAssertNoThrowSpecificError(kind: ErrorType, _ message: String = "", file: String = __FILE__, line: UInt = __LINE__, _ block: () throws -> ())
{
    do {try block()}
    catch let error as NSError
    {
        let unwanted = kind as NSError
        if ((error.domain == unwanted.domain) && (error.code == unwanted.code))
        {
            let msg = (message == "") ? "Tested block threw unexpected \(kind) error." : message
            XCTFail(msg, file: file, line: line)
        }
    }
}