testing.m

#pragma mark - Simple Unit Test

- (void)test_callSomeoneWith_giveSomething_getSomething {
  MyClass *sut = [MyClass new];
  NSString *input = @„give something“;
  NSString *expectedResult = @„get something“;
  NSString *result = [sut callSomeoneWith:input];
  XCTAssertEqualObjects(result, expectedResult);
}

#pragma mark - Asynchronous unit test

- (void)test_eventuallyCallSomeoneWith_giveSomething_getSomething {
  MyClass *sut = [MyClass new];
  NSString *input = @„give something“;
  NSString *expectedResult = @„get something“;
  XCTestExpection *expectation = [self expectationWithDescription:@„calling someone“];
  [sut callSomeoneWith:input completion:^(NSString *result) {
    XCTAssertEqualObjects(result, expectedResult);
    [expectation fulfill];
  }];
  [self waitForExpectations: @[expectation] timeout:1.0];
}

#pragma mark - Mock test class

@interface TestableMyClass: MyClass 
@property (nonatomic) BOOL networkCalled;
@end

@implementation TestableMyClass
- (void)remoteCall {
  self.networkCalled = YES;
}
@end

- (void)test_callSomeplace_networkWasCalled {
  TestableMyClass *sut = [TestableMyClass new];
  [sut callSomeplace];
  XCTAssertTrue(sut.networkCalled);
}