Variable destroyed in unit test - ios

all:
I've the following unit tests class (implementation file shown):
#implementation SampleTests {
A* c;
NSString* token;
}
- (void)setUp
{
[super setUp];
// Set-up code here.
c = [[A alloc] init];
}
- (void)tearDown
{
// Tear-down code here.
[super tearDown];
}
- (void)testA
{
token = #"sample";
}
-(void)testB
{
[c method:token]; // <-- fails because token is nil, but c has a correct value. Why!
}
#end
When I run my tests, testB fails because token is nil, but c it's ok, so why is it token destroyed?

Every time you run your unit tests, each test case is invoked independently. Before each test case runs, the setUp method is called, and afterwards the tearDown method is called.
So if you want to share token among tests, you should add
token = #"sample"; // or smth else
to your setUp method.

As far as I know, the current implementation runs the test methods in their alphabetic order, so your example should run without problems.
Usually, if I want something to be tested first, I name the methods test1_criticalFeature, test2_dependentFeatures etc.

The order that test methods are executed in is not guaranteed, so it could be the case that testB is run before testA or even in the future that they are run in parallel.

Related

Use of undeclared identifier error in my case

My code invokes a C library function:
#implementation Store
...
-(void) doWork {
// this is a C function from a library
int data = getData();
...
}
end
I am unit testing the above function, I want to mock the C function getData() in my test, here is my test case:
#interface StoreTests : XCTestCase {
int mData;
Store *store;
}
#end
#implementation StoreTests
-(void) setUp {
[super setUp];
mData = 0;
store = [[Store alloc] init];
}
-(void) testDoWork {
// this call will use the mocked getData(), no problem here.
[store doWork];
}
// mocked getData()
int getData() {
mData = 10; // Use of undeclared identifier 'mData', why?
return mData;
}
...
#end
Why I get complier error:
Use of undeclared identifier 'mData' inside mocked getData() function?
You are misunderstanding how instance methods and variables work.
Every instance method has a variable self which references the current instance (or "current object") and a use of an instance variable, such as mData, is shorthand for accessing that variable using self, e.g self->mData, where -> is the (Objective-)C operator for field access. So your setup method written "long hand" is:
-(void) setUp {
[super setUp];
self->mData = 0;
self->store = [[Store alloc] init];
}
But where does self, the reference to the instance, itself come from? Well it's not magical, just hidden, it is passed to an instance method automatically as a hidden extra argument. At this point which switch to pseudo-code to show this. Your setup method is effectively compiled as:
-(void) setUp withSelf:(StoreTest *)self {
[super setUp];
self->mData = 0;
self->store = [[Store alloc] init];
}
and a call such as:
StoreTests *myStoreTests = ...
[myStoreTests setup];
is effectively compiled as something like:
[myStoreTests setup withSelf:myStoreTests];
automatically adding the extra self argument.
Now all the above only applies to methods, and enables them to access instance variables and methods, it does not apply to plain C functions - they have no hidden self argument and cannot access instance variables.
The solution you mention in the answer you added of declaring mData outside of the interface:
int mData;
#interface StoreTests : XCTestCase {
Store *store;
}
#end
changes mData into a global variable, instead of being an instance variable. C functions can access global variables. However this does mean that every instance of the class shares the same mData, there is only one mData in this case rather than one for every instance.
Making an instance variable into a global is therefore not a general solution to to issues like this, however as it is unlikely that you will have more than one instance of your StoreTests class it is a suitable solution in this case.
You should however make one change: you can only have one global variable with a given name with a program, so your mData must be unique and is accessible by any code within your program, not just the code of StoreTests. You can mitigate this my declaring the variable as static:
static int mData;
this keeps the variable as global but only makes it visible to code within the same file as the declaration, which is probably just the code of StoreTests.
HTH
I found one solution for my question, that is declare mData above #interface StoreTests : XCTestCase, something like this:
int mData;
#interface StoreTests : XCTestCase {
Store *store;
}
#end
...

Check argument value passed into function in unit test

I am using OCMock v3 do unit testing, I want to test the following piece of code:
#implementation School
-(void) handleStudent:(Student*) student{
Bool result = [self checkIdentityWithName:student.name age:student.age];
...
}
...
#end
In my following test case I created a student instance with name "John", age 23. and then I run the function under test:
-(void) testHandleStudent{
Student *student = [Student initWithName:#"John" age:23];
// function under test
[schoolPartialMock handleStudent:student];
// I want to not only verify checkIdentityWithName:age: get called,
// but also check the exact argument is passed in. that's John 23 in this case
// how to check argument ?
}
In my test case, I want to verify that the exact arguments values are passed into function checkIdentityWithName:age: . that's name "John" and age 23 are used. How to verify that in OCMock v3? (There is no clear example in its documentation how to do it.)
You can make it like that
-(void) testHandleStudent{
id studentMock = OCMClassMock([Student class]);
OCMStub([studentMock name]).andReturn(#"John");
OCMStub([studentMock age]).andReturn(23);
[schoolPartialMock handleStudent:studentMock];
OCMVerify([schoolPartialMock checkIdentityWithName:#"John" age:23]);
}
or
-(void) testHandleStudent{
id studentMock = OCMClassMock([Student class]);
OCMStub([studentMock name]).andReturn(#"John");
OCMStub([studentMock age]).andReturn(23);
OCMExpect([schoolPartialMock checkIdentityWithName:#"John" age:23]);
[schoolPartialMock handleStudent:studentMock];
OCMVerifyAll(schoolPartialMock);
}
Hope this help

Unit test a very simple method, but failed

I have a simple School class which defines a init method:
#implementation School
- (id) init {
self = [super init];
if (self) {
// call class method of MyHelper class
if ([MyHelper isWeekend]) {
[MyHelper doSomething];
}
}
}
#end
(MyHelper is a class contains only class methods, the isWeekend is a class method returns a boolean value)
I use OCMock to unit test this simple init method:
- (void)testInit {
// mock a school instance
id schoolMock = [OCMockObject partialMockForObject:[[School alloc] init]];
// mock class MyHelper
id MyHelperMock = OCMStrictClassMock([MyHelper class]);
// stub class method 'isWeekend()' to return true
OCMExpect([MyHelperMock isWeekend]).andReturn(true);
// run init method
[schoolMock init];
// verify
OCMVerify([MyHelperMock isWeekend]);
}
But when run it, I get error:
OCMockObject(MyHelper): Method isWeekend was not invoked. why?
You've created a mock for the MyHelper class, but this isn't going to be used within the implementation of your School object. You'd only get the mocked response if you wrote [MyHelperMock isWeekend], which you can't do inside the initialiser without rewriting it for tests.
To make your School class more testable you should be passing in any dependencies on initialisation. For example, you could pass in the isWeekend value as part of the initialiser, instead of obtaining it inside the method, or pass in the class object (MyHelper or MyHelperMock).
It's worth noting that finding certain classes or methods difficult to test because of things like this is often a good indicator that your code isn't structured very well.

stub function is not working in my test case [duplicate]

This question already has an answer here:
How to mock an object with OCMock which isn't passed as a parameter to method?
(1 answer)
Closed 6 years ago.
I am using OCMock 3 to write my unite tests in iOS project.
I have a foo method under School class:
#implementation School
-(NSString *)foo:
{
// I need to mock this MyService instance in my test
MyService *service = [[MyService alloc] init];
// I need to stub the function return for [service getStudent]
Student *student = [service getStudent];
if (student.age == 12) {
//log the age is 12
} else {
//log the age is not 12
}
...
}
The Student looks like this:
#interface Student : NSObject
#property NSInteger age;
...
#end
In my test case, I want to stub the method call [service getStudent] to return a Student instance with age value 12 I defined:
// use mocked service
id mockService = OCMClassMock([MyService class]);
OCMStub([[mockService alloc] init]).andReturn(mockService);
// create a student instance (with age=12) which I want to return by function '-(Student*) getStudent:'
Student *myStudent = [[Student alloc] init];
myStudent.age = 12;
// stub function to return 'myStudent'
OCMStub([mockService getStudent]).andReturn(myStudent);
// execute foo method
id schoolToTest = [OCMockObject partialMockForObject:[[School alloc] init]];
[schoolToTest foo];
When I run my test case, however, the student returned by -(Student*)getStudent: method is not with age 12, why?
===== UPDATE ====
I noticed in internet, somebody suggested to separate the alloc and init to stub. I also tried it but it doesn't work as it says:
// use mocked service
id mockService = OCMClassMock([MyService class]);
OCMStub([mockService alloc]).andReturn(mockService);
OCMStub([mockService init]).andReturn(mockService);
// stub function to return 'myStudent'
OCMStub([mockService getStudent]).andReturn(myStudent);
When I do this & run my test case, the real implementation of -(Student*)getStudent: method get called... I can't understand why people says it works.
You cannot mock the init method. This is stated in the documentation (Section 9.3), but maybe it's too hidden.

TyphoonPatcher for mocking in unit tests

I have Assembly:
#interface MDUIAssembly : TyphoonAssembly
#property (nonatomic, strong, readonly) MDServiceAssembly *services;
#property (nonatomic, strong, readonly) MDModelAssembly *models;
- (id)choiceController;
#end
#implementation MDUIAssembly
- (void)resolveCollaboratingAssemblies
{
_services = [TyphoonCollaboratingAssemblyProxy proxy];
_models = [TyphoonCollaboratingAssemblyProxy proxy];
}
- (id)choiceController
{
return [TyphoonDefinition withClass:[MDChoiceViewController class]
configuration: ^(TyphoonDefinition *definition) {
[definition useInitializer:#selector(initWithAnalytics:diary:)
parameters: ^(TyphoonMethod *initializer) {
[initializer injectParameterWith:[_services analytics]];
[initializer injectParameterWith:[_models diary]];
}];
}];
}
#end
Here what I'm trying to do in tests:
- (void)setUp
{
patcher = [TyphoonPatcher new];
MDUIAssembly *ui = (id) [TyphoonComponentFactory defaultFactory];
[patcher patchDefinition:[ui choiceController] withObject:^id{
return mock([MDChoiceViewController class]);
}];
[[TyphoonComponentFactory defaultFactory] attachPostProcessor:patcher];
}
- (void) tearDown
{
[super tearDown];
[patcher rollback];
}
Unfortunately my setUp fails with next message:
-[MDChoiceViewController key]: unrecognized selector sent to instance 0xbb8aaf0
What I'm doing wrong?
You've encountered a poor design choice on Typhoon's part, but there's an easy work-around.
You're using this method:
[patcher patchDefinition:[ui choiceController] withObject:^id{
return mock([MDChoiceViewController class]);
}];
. . which is expecting a TyphoonDefinition as argument. When bootstrapping Typhoon:
We start with one ore more TyphoonAssembly subclasses, which Typhoon instruments to obtain recipes for building components. These TyphoonAssembly sub-clases are then discarded.
We now have a TyphoonComponentFactory that will allow any of your TyphoonAssembly interfaces to pose in front of it. (This is so you can have multiple configs of the same class, while still avoiding magic strings, allows auto-completion in your IDE, etc).
When the TyphoonPatcher was written it was designed for the case where you obtain a new TyphoonComponentFactory for your tests (recommended), like this:
//This is an actual TyphoonAssembly not the factory posing as an assembly
MiddleAgesAssembly* assembly = [MiddleAgesAssembly assembly];
TyphoonComponentFactory* factory = [TyphoonBlockComponentFactory factoryWithAssembly:assembly];
TyphoonPatcher* patcher = [[TyphoonPatcher alloc] init];
[patcher patchDefinition:[assembly knight] withObject:^id
{
Knight* mockKnight = mock([Knight class]);
[given([mockKnight favoriteDamsels]) willReturn:#[
#"Mary",
#"Janezzz"
]];
return mockKnight;
}];
[factory attachPostProcessor:patcher];
Knight* knight = [(MiddleAgesAssembly*) factory knight];
What happened:
So the problem is that the TyphoonPatcher is expecting TyphoonDefinition from the TyphoonAssembly and instead it is getting an actual component from a TyphoonComponentFactory.
Very confusing, and that way of obtaining a patcher should be deprecated.
Solution:
Use the following instead:
[patcher patchDefinitionWithSelector:#selector(myController) withObject:^id{
return myFakeController;
}];
Here's some extra advice to go along with the main answer . . .
Unit Tests vs Integration Tests:
In Typhoon we adhere to the traditional terms:
Unit Tests : Testing your class in isolation from collaborators. This is where you inject test doubles like mocks or stubs in place of all of the real dependencies.
Integration Tests: Testing your class using real collaborators. Although you may patch our a component in order to put the system in the required state for that test.
So any test that uses TyphoonPatcher would probably be an integration test.
More info here: Typhoon Integration Testing
Resolve Collaborating Assemblies:
This was required in earlier version of Typhoon, but is not longer needed. Any properties that are are sub-class of TyphoonAssembly will be treated as collaborating assemblies. Remove the following:
- (void)resolveCollaboratingAssemblies
{
_services = [TyphoonCollaboratingAssemblyProxy proxy];
_models = [TyphoonCollaboratingAssemblyProxy proxy];
}
Tests instantiate their own assembly:
We recommend that tests instantiate and tear down their on TyphoonComponentFactory. The advantages are:
[TyphoonComponentFactory defaultFactory] is a global and has some drawbacks.
Integration tests can define their own patches without having to worry about putting the system back in the original state.
In addition to using TyphoonPatcher, if you wish you can create an assembly where the definitions for some components are overridden.

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