I am developing an iOS application and am trying to integrate Typhoon into the testing. I am currently trying to mock out a dependency in a view controller that comes from the storyboard, so with in my assembly:
public dynamic var systemComponents: SystemComponents!
public dynamic func storyboard() -> AnyObject {
return TyphoonDefinition.withClass(TyphoonStoryboard.self) {
(definition) in
definition.useInitializer("storyboardWithName:factory:bundle:") {
(initializer) in
initializer.injectParameterWith("Main")
initializer.injectParameterWith(self)
initializer.injectParameterWith(NSBundle.mainBundle())
}
}
}
I want to create a CameraModeViewController (the class I am unit testing) with its dependency upon a system-camera-functions-providing protocol mocked out. The dependency is dynamic var cameraProvider: CameraAPIProvider?. I think I correctly created a replacement collaborating assembly to replace systemComponents; MockSystemComponents is a subclass of SystemComponents that overrides functions. This is where I inject the mock:
let assembly = ApplicationAssembly().activateWithCollaboratingAssemblies([
MockSystemComponents(camera: true)
])
let storyboard = assembly.storyboard()
subject = storyboard.instantiateViewControllerWithIdentifier("Camera-Mode") as! CameraModeViewController
The next line of code in the tests is let _ = subject.view, which I learned is a trick to call viewDidLoad and get all the storyboard-linked IBOutlets, one of which is required for this test.
However, I am getting very mysterious result: sometimes but not always, all the tests fail because in the viewDidLoad I make a call to the dependency (cameraProvider), and I get an "unrecognized message sent to class" error. The error seems to indicate that at the time the message is sent (which is a correct instance method in protocol CameraAPIProvider) the field is currently a CLASS and not an instance: it interprets the message as +[MockSystemCamera cameraStreamLayer] as reported in the error message.
~~~BUT~~~
Here's the kicker: if I add a breakpoint between the calls to assembly.storyboard() and subject.view, the tests always pass. Everything is set up correctly, and the message is correctly sent to an instance without this "class method" bogus interpretation. Therefore, I have to wonder if Typhoon does some kind of asynchronous procedure in the injection that I have to wait for? Possibly only when dealing with storyboard-delivered view controllers? And if so, is there any way to make sure it blocks?
After digging around in Typhoon's source for a while, I get the impression that in the TyphoonDefinition(Instance Builder) initializeInstanceWithArgs:factory: method there is an __block id instance that is temporarily a Class type, and then is replaced with an instance of that type; and possibly this can be called asynchronously without blocking, so the injected member is left as a Class type?
UPDATE: Adding the code for MockSystemComponents(camera:). Note that SystemComponents inherits from TyphoonAssembly.
#objc
public class MockSystemComponents: SystemComponents {
var cameraAvailable: NSNumber
init(camera: NSNumber) {
self.cameraAvailable = camera
super.init()
}
public override func systemCameraProvider() -> AnyObject {
return TyphoonDefinition.withClass(MockSystemCamera.self) {
(definition) in
definition.useInitializer("initWithAvailable:") {
(initializer) in
initializer.injectParameterWith(self.cameraAvailable)
}
}
}
}
UPDATE #2: I tried replacing the constructor injection in the MockSystemComponents.systemCameraProvider() with a property injection. Different issue, but I suspect it's equivalent in cause: now, the property that is injected (declared optional) is still nil some of the time when I go to unwrap it (but not always -- probably about 4/5 of test runs fail, about the same as before).
UPDATE #3: have tried using the following code block, using factory construction according to this answer (note that setting factory directly didn't work as that OP did, but I think I correctly used the feature added in response to Jasper's issue). The results are the same as when using property injection like Update #2 above), so no dice there.
This issue was in fact arising even before the call to the instantiation. In fact, the problem was assemblies aren't generally intended to be stateful. There are a few ways to get around this, but the one I used -- having a member variable and an initializer method -- is NOT recommended. The problem with doing this is that in the activateWithCollaboratingAssemblies method, all the instance methods of the assembly are enumerated for definitions, and initializers will actually get called on the collaborating assembly. Consequently, even if you create your assembly with an initializer, it may get called again with a bogus value.
Note that the reason there appeared to be async behavior is actually that there is nondeterministic order in which definitions are assembled (property of storing them in an NSDictionary). This means that if activateWithCollaboratingAssemblies happens to enumerate methods which depend on state first, they'll work fine; but if the initializer is enumerated first, and the state is destroyed, definitions that are created after will be borked.
Related
I have two frameworks A and B. I have a public function inside B called getMap() which returns a copy of a map(which is a private variable in B). So I call getMap() in A to get this value. This is fine because it's a copy so whatever I do to the returned value it doesn't affect the actual variable inside B.
Now I did some processing to this value, I need to pass it back to B. Here is the problem: In order to pass it back, it has to be a public function, but I don't want other frameworks or application to call this function because only A should be making changes to this map value.
Is there any way to specify in B that only if A is calling the function then the value should be set, otherwise ignoring anyone else who is using this function? I've heard you can use delegate/protocol to achieve this but I don't understand.
Yes you should be able to achieve this using delegate/protocols. The protocol will still have to be public which means any class could implement the protocol but the simple solution to this would be to just not implement it any other class.
You would create the the protocol in framework B like this:
protocol FrameworkBDelegate {
func sendMapChanges(map: Map)
}
Then call the delegate method when you're ready send it back to the other framework:
func changeMap() {
var map = frameworkA.getMap()
// Do stuff to map...
delegate.sendMapChanges(map: map)
}
I don't want to write a whole tutorial on how implement delegation so here's a good one from Swift by Sundell: here
Let me know if you need any help.
This is not possible out of the box.
If you create a Framework than you have to decide if a method/class needs to be public or not. If a method is public than there isn't an out of the box solution which delivers a bullet proof solution which solves your requirement. In the end the method is public to ALL consumers of Framework B.
So, you will end up implementing some kind of access control mechanisms within Framework B. This means that Framework A needs to authenticate itself in some way (access code etc.).
The delegate pattern will not solve your issue as well, hence it also has to be public, so that Framework A can use it. However, if it's public than all consumers of Framework B can use it.
Edit: So far it looks like the answer to my question is, "You can't do that in Swift." I currently have a solution whereby the subclass names are listed in an array and I loop around and instantiate them to trigger the process I'm describing below. If this is the best that can be done, I'll switch it to a plist so that least it's externally defined. Another option would be to scan a directory and load all files found, then I would just need to make sure the compiler output for certain classes is put into that directory...
I'm looking for a way to do something that I've done in C++ a few times. Essentially, I want to build a series of concrete classes that implement a particular protocol, and I want to those classes to automatically register themselves such that I can obtain a list of all such classes. It's a classic Prototype pattern (see GoF book) with a twist.
Here's my approach in C++; perhaps you can give me some ideas for how to do this in Swift 4? (This code is grossly simplified, but it should demonstrate the technique.)
class Base {
private:
static set<Base*> allClasses;
Base(Base &); // never defined
protected:
Base() {
allClasses.put(this);
}
public:
static set<Base*> getAllClasses();
virtual Base* clone() = 0;
};
As you can see, every time a subclass is instantiated, a pointer to the object will be added to the static Base::allClasses by the base class constructor.
This means every class inherited from Base can follow a simple pattern and it will be registered in Base::allClasses. My application can then retrieve the list of registered objects and manipulate them as required (clone new ones, call getter/setter methods, etc).
class Derived: public Base {
private:
static Derived global; // force default constructor call
Derived() {
// initialize the properties...
}
Derived(Derived &d) {
// whatever is needed for cloning...
}
public:
virtual Derived* clone() {
return new Derived(this);
}
};
My main application can retrieve the list of objects and use it to create new objects of classes that it knows nothing about. The base class could have a getName() method that the application uses to populate a menu; now the menu automatically updates when new subclasses are created with no code changes anywhere else in the application. This is a very powerful pattern in terms of producing extensible, loosely coupled code...
I want to do something similar in Swift. However, it looks like Swift is similar to Java, in that it has some kind of runtime loader and the subclasses in this scheme (such as Derived) are not loaded because they're never referenced. And if they're not loaded, then the global variable never triggers the constructor call and the object isn't registered with the base class. Breakpoints in the subclass constructor shows that it's not being invoked.
Is there a way to do the above? My goal is to be able to add a new subclass and have the application automatically pick up the fact that the class exists without me having to edit a plist file or doing anything other than writing the code and building the app.
Thanks for reading this far — I'm sure this is a bit of a tricky question to comprehend (I've had difficulty in the past explaining it!).
I'm answering my own question; maybe it'll help someone else.
My goal is to auto initialize subclasses such that they can register with a central authority and allow the application to retrieve a list of all such classes. As I put in my edited question, above, there doesn't appear to be a way to do this in Swift. I have confirmed this now.
I've tried a bunch of different techniques and nothing seems to work. My goal was to be able to add a .swift file with a class in it and rebuild, and have everything automagically know about the new class. I will be doing this a little differently, though.
I now plan to put all subclasses that need to be initialized this way into a particular directory in my application bundle, then my AppDelegate (or similar class) will be responsible for invoking a method that scans the directory using the filenames as the class names, and instantiating each one, thus building the list of "registered" subclasses.
When I have this working, I'll come back and post the code here (or in a GitHub project and link to it).
Same boat. So far the solution I've found is to list classes manually, but not as an array of strings (which is error-prone). An a array of classes such as this does the job:
class AClass {
class var subclasses: [AClass.Type] {
return [BClass.self, CClass.self, DClass.self]
}
}
As a bonus, this approach allows me to handle trees of classes, simply by overriding subclasses in each subclass.
I'm a seasoned Objective-c programmer but I can't say the same for Swift, I'm having a hard time unit testing a class in swift without using frameworks like OCMock.
The Problem: I'm integrating Firebase into a mixed Objective-C/Swift project, and I need to configure it based on the build configuration of the app.
I've written a Swift class for that (that will be used by the obj-c app delegate), however since the firebase framework is configured trough a static class method, precisely FIRApp.configure(with: FIROptions), I need to mock this method somehow in order to unit test it.
My code, without any handle for Dependency Injection, looks like that:
#objc class FirebaseConfigurator: NSObject{
func configureFirebase(){
let config = configManager.buildConfiguration
var optionsPlistBaseName = getPlistName()
let optionsFile = Bundle.main.path(forResource: optionsPlistBaseName, ofType: "plist")
guard let opts = FIROptions(contentsOfFile: optionsFile) else{
assert(false, "fatal: unable to load \(optionsFile)")
return
}
FIRApp.configure(with: opts)
}
func getPlistName() -> String{
// retrieves correct plist name and returns it
}
}
I've done some research but so far I didn't find nothing that fits my solution, however I was thinking of one of the following:
I could pass a function that defaults to FIRApp.configure(with:) however I should do this from objective-c and the function also accepts a parameter, I was struggling with the syntax
I could use a wrapper around FIRApp, but I wanted to avoid it unless the only viable clean solution.
I could keep on playing with protocols and do dependency inversion, however being the method static I was struggling with the syntax again, I can't find an easy way to do DI with a mock class with a static method.
As a reference (both personal and for who might need it) these are some of the resources I found useful and upon which I will keep on digging:
Dealing with static cling in Swift
This Question
This article about generic unit testing
In the meanwhile, every help would be really appreciated.
As a sidenote, there are many ways I can solve this problem without struggling with mocking a static class method, but my aim here is to find out a way of mocking it in order to have a better understanding of the best practices when testing more complex situations.
You can indeed do any of those.
Closure Argument
You can have your configureFirebase function take an "applier" closure that defaults to what you originally used:
func configureFirebase(
using apply: (_ options: FIROptions) -> Void
= { opts in FIRApp.configure(opts) }
) {
// building |opts| as before
// Now replace this: FIRApp.configure(with: opts)
apply(opts)
}
Protocols
You need a Configurable protocol, and then to conform FIRApp to it for the default case:
protocol Configurable {
static func configure(with options: FIROptions)
}
extension FIRApp: Configurable {}
class FirebaseConfigurator {
var configurable: Configurable
init(configurable: Configurable = FIRApp) {
self.configurable = configurable
}
func configureFirebase() {
//load |opts|…
configurable.configure(with: opts)
}
}
If you're just going to use this in one method, though, it's merely transient state, and it should probably be a function argument rather than stored property.
(If it's unclear whether it's persistent or transient state because the whole point of the class is to call a single function, perhaps you don't even need a class, just a function.)
Am having a little trouble understanding what and what cannot be done using FakeItEasy. Suppose I have a class
public class ToBeTested{
public bool MethodToBeTested(){
SomeDependentClass dependentClass = new SomeDependentClass();
var result = dependentClass.DoSomething();
if(result) return "Something was true";
return "Something was false";
}
}
And I do something like below to fake the dependent class
var fakedDepClass = A.Fake<DependentClass>();
A.CallTo(fakedDepClass).WithReturnType<bool>().Returns(true);
How can i use this fakedDepClass when am testing MethodToBeTested. If DependentClass was passed as argument, then I can pass my fakedDepClass, but in my case it is not (also this is legacy code that I dont control).
Any ideas?
Thanks
K
Calling new SomeDependentClass() inside MethodToBeTested means that you get a concrete actual SomeDependentClass instance. It's not a fake, and cannot be a FakeItEasy fake.
You have to be able to inject the fake class into the code to be tested, either (as you say) via an argument to MethodToBeTested or perhaps through one of ToBeTested's constructors or properties.
If you can't do that, FakeItEasy will not be able to help you.
If you do not have the ability to change ToBeTested (and I'd ask why you're writing tests for it, but that's an aside), you may need to go with another isolation framework. I have used TypeMock Isolator for just the sort of situation you describe, and it did a good job.
I've seen this question regarding partial stubs, but it does not quite tell me what I need to know.
I understand that, if I am using a Moles stub for a class (let's say, for DataService, I'm using SDataService), I can set the CallBase property to true so that, if there is no delegate for a particular method, the base implementation's method will be called. Great, but how do I assign a delegate to a particular method in this case?
If there is no way to do that, say I have an interface IDataService that I stub using SIDataService. I can easily assign a delegate to a method here. But, how do I tell it to call the corresponding method on DataService (an implementation of IDataService) if there is no delegate for a given method?
Thank you!
Edit:
I see now that the method needs to be virtual to be overridden in the first scenario above. I don't think that makes a whole lot of sense, but it is what it is.
So, focusing on the second scenario, would I have to create a Behavior? (And why isn't there one already for stubs like there is for moles?) Or is there a simpler way?
Delegates (detours) are set to stubs types the same way as mole types. For example, SIDataService.GetMemberProfile() is configured to return a mock object like this:
var memberMock = new Member() { Firstname="Joe", LastName="Schmoe" };
var stub = new SIDataService();
stub.GetMemberProfileMember = i => memberMock;