Test if a function is called in Unit Testing for Objective C

Question

In the implementation file (.mm) I have a function that calls different APIs depending on the value of a boolean isTrue which is set in other APIs

@implementation Controller

-(void) setProperty:(Id)Id value:(NSObject*)value
{
   if(value) {
      if(self.isTrue) {
         [self function1]
      } else {
         [self function2]
      }
   }
}

Now I need to write a test where for different values of isTrue, I need to test if the correct function is being called.

I wrote something like:

-(void) testCaseforProperty
{
   _controller.isTrue = true;
   _controller setProperty:0 value:@YES];
  // I need to check if function1 is called here
}

Can anyone please tell me how to write a test here in place of the comment in order to test that function1 is called here either with OCMock or XCTest or any other way?

Answer 1

Use a protocol

@protocol FunctionsProviding
- (void)function1;
- (void)function2;
@end

Your object being tested could look like this:

@interface Controller: NSObject<FunctionsProviding>
@end

@interface Controller ()

@property (nonatomic, weak) id<FunctionsProviding> functionsProvider;
@property (nonatomic, assign) BOOL isTrue;
- (void)function1;
- (void)function2;
@end

@implementation ViewController
- (void)function1 {
    //actual function1 implementation
}

- (void)function2 {
    //actual function2 implementation
}

-(void) setProperty:(id)Id value:(NSObject*)value
{
   if(value) {
      if(self.isTrue) {
          [self.functionsProvider function1];
      } else {
          [self.functionsProvider function1];
      }
   }
}

- (instancetype)init {
    self = [super init];
    if (self) {
        self.functionsProvider = self;
        return self;
    }
    return nil;
}

- (instancetype)initWithFunctionsProvider:(id<FunctionsProviding> )functionsProvider {
    self = [super init];
    if (self) {
        self.functionsProvider = functionsProvider;
        return self;
    }
    return nil;
}
@end

You would use a mock to check whether a function gets called

@interface FunctionsProviderMock: NSObject<FunctionsProviding>
- (void)function1;
- (void)function2;

@property (nonatomic, assign) NSUInteger function1NumberOfCalls;
@property (nonatomic, assign) NSUInteger function2NumberOfCalls;
@end

@implementation FunctionsProviderMock
- (void)function1 {
    self.function1NumberOfCalls += 1;
}
- (void)function2 {
    self.function2NumberOfCalls += 1;
}
@end

The test could look like this:

 - (void)test {
     FunctionsProviderMock *mock = [FunctionsProviderMock new];
     Controller *sut = [[Controller alloc] initWithFunctionsProvider: mock]];

     sut.isTrue = true;
     [sut setProperty:0 value:@YES];

     XCTAssertTrue( mock.function1NumberOfCalls, 1);
     XCTAssertTrue( mock.function2NumberOfCalls, 1);

}