Accessing readonly property in testing iOS Swift - objective-c

Question

I am pretty new to iOS and Swift and currently I'm facing a problem with writing a Unit Test. I have a class (let's suppose it is called A) which has (readonly property from Objective-C) and in my test I want to have object of this class to pass to the method which later does something with it. Oh, I don't have any initializers as well... My question is, how to test such think? Maybe I have to mock such object somehow?
------EDIT-----
Okay. My post wasn't quite precise. Okay, so I know only basics of Swift (unfortunately I don't have time now to learn Objective - C as I was asked to write sth in Swift). I have a class provided by some company in which I have a class (written in Objective-C) like:
#interface MainClassX : NSObject
#property (nonatomic, strong, readonly) NSString* code;
#property (nonatomic, strong, readonly) NSArray<XYZ*>* classification;
#end
And in my test want to create an object of this class and init at least 'code' property... but the setter is private so I can't do any 'inheritance trick'...? Is there any option to do it or should I do it another way? The problem is that I want to test a method which takes array of such objects and does sth with them.

Answer 1

It's pretty tricky because they wanted those properties to be readonly, why do you want to test them?
Regardless the purpose, you can do these steps:
1. Look into adding methods to that class using Category (in Objective C), or extension(in Swift).
2. Implement that new init method, set the code properpty using Key-Value Programming
I have managed to do it real quick in Objective C, it's pretty straight forward to convert to Swift.
#implementation MainClassX(Test)
-(instancetype)initWithCode:(NSString *)code {
self = [self init];
if (self) {
[self setValue:code forKey:#"code"];
}
return self;
}
#end
Test it:
MainClassX *test = [[MainClassX alloc] initWithCode:#"TEST"];
NSLog(#"code: %#", test.code); // Should print out "TEST" in the console
Swift:
extension MainClassX {
convenience init(_ code: String) {
self.init()
self.setValue(code, forKey: "code")
}
}
In the unit test:
import XCTest
#testable import YourAppModule
class YourAppModuleTests: XCTestCase {
override func setUp() {
super.setUp()
// Put setup code here. This method is called before the invocation of each test method in the class.
}
override func tearDown() {
// Put teardown code here. This method is called after the invocation of each test method in the class.
super.tearDown()
}
func testExample() {
// This is an example of a functional test case.
// Use XCTAssert and related functions to verify your tests produce the correct results.
let cls = MainClassX("TEST")
XCTAssert(cls.code == "TEST")
}
func testPerformanceExample() {
// This is an example of a performance test case.
self.measure {
// Put the code you want to measure the time of here.
}
}
}

Answer 2

You are likely looking for dependancy injection. This is a way that you can initialize a class with an optional value that can set values for testing, as you want to do.
The following is a simple example.
Create an optional initialize for your Objective-C class:
- (instancetype)initWithOption:(NSString *)option {
self = [super init];
if (self) {
self.option = option;
}
return self;
}
You can have it such that when you normally call the class, you call its default init. But for testing, initialize it with this function. Another thing to consider if you may want to have a protected header file (such as classname_protected.h) which you only use in your unit tests so that you do not expose this function to your application.
Without seeing more of your test, it is a bit difficult to add on to this, but DI is likely where you need to go for it.