Testing for XCTAssertThrows in Swift

TestCase.swift

class ExceptionTestCase: XCTestCase {
  func raisesException() {
    var exception = NSException(name: NSInternalInconsistencyException, reason: "Testing exceptions", userInfo: nil)
    XCTAssertThrows({ exception.raise() }, "Should raise an exception)
    XCTAssertThrowsSpecific({ exception.raise() }, NSInternalInconsistencyException, "Should raise NSInternalInconsistencyException")
  }
}

Tests-Bridging-Header.h

#import "XCTestCase+Exceptions.h"

XCTestCase+Exceptions.h

@import Foundation;
@import XCTest;

@interface XCTestCase (Exceptions)

- (void)XCTAssertThrows:(void (^)(void))block :(NSString *)message;
- (void)XCTAssertThrowsSpecific:(void (^)(void))block :(NSString *)name :(NSString *)message;

@end

XCTestCase+Exceptions.m

#import "XCTestCase+Exceptions.h"

@implementation XCTestCase (Exceptions)

- (void)XCTAssertThrows:(void (^)(void))block :(NSString *)message {
  XCTAssertThrows(block(), @"%@", message);
}

- (void)XCTAssertThrowsSpecific:(void (^)(void))block :(NSString *)exceptionName :(NSString *)message {
  BOOL __didThrow = NO;
  @try {
    block();
  }
  @catch (NSException *exception) {
    __didThrow = YES;
    XCTAssertEqualObjects(exception.name, exceptionName, @"%@", message);
  }
  @catch (...) {
    __didThrow = YES;
    XCTFail(@"%@", message);
  }

  if (!__didThrow) {
    XCTFail(@"%@", message);
  }
}

@end

Thanks. I ran into a problem when my block in Swift doesn't have a return value of Void (to match the Obj-C definition).

In particular: my block had a single expression whose type was "String!", and I was getting "error: 'String!' is not a subtype of 'Void'"

It was quickly solved by changing the return type of the block to 'id', but then it's incompatible with blocks that don't return anything. I haven't needed to go any farther, so I'm not sure what the best solution is.

Thanks. I got a little confused with the example that was shown, to use your solution I had to code something like this:

func testSomething () {
    var exception = NSException(
        name: NSInvalidArgumentException,
        reason: "some reason",
        userInfo: nil
    )

    XCTAssertThrowsSpecific(
        {
            var object =  Object ()
        },
        NSInvalidArgumentException,
        "some message"
    )
}