This question is more like open discussion. I would like to start with an example. Suppose there is one service FooService
public interface IFooService { void Method1(){}}
public class FooService: IFooService { void Method1(){ ... }}
In order to test the service , we write the unit test code like below, no external services
public void TestMethod1(){ ... }
Then suppose in Method1 we need to use another class called AService which inherit from IAService
public interface IAService {void AMethod1(){}}
public class AService : IAService { void AMethod1() {}}
public class FooService : IFooService {
private IAService a;
public FooService (IAService a){ this.a = a;}
void Method1(){ a.AMethod1(); ..... business logic ..... }
}
Then we have to refactor the unit test to mock AService
public void TestMethod1(){
IMockAService aService = MockRepository.StrickMock<IAService>();
.....
}
So when need more external services, we have to add mock service, if some of services changed the logic or add or remove parameters, and so on. If there are 100 test cases, we have to modify all of test cases.
So what's the best solution for mocking increasing external services and effective way to handle any changes of external dependencies for example : add/remove parameters of methods.
thanks
Most times for me it's enough to create the class under test in a Setup method, leaving you with only one place to adapt when the constructor signature changes.
Alternatively you can move construction of the class under test to a private method.
Same goes for methods. Often you can wrap the call to a method under test in a private method. This is especially helpful, if you don't have to set up all passed parameters in every test, but can use defaults, which you might have prepared in your Setup method.
Related
Can I run a custom rule only for a particular test method in a test class?
public class TestClassExample
{
#Rule
public CustomRuleForOneEqualsOne customRuleForOneEqualsOne = new CustomRuleForOneEqualsOne();
#Test
public void test_OneEqualsOne()
{
assertEquals(1, 1);
}
#Test
public void test_TwoEqualsTwo()
{
assertEquals(2, 2);
}
}
In the above test class can I use my customRuleForOneEqualsOne rule be used only for test method test_OneEqualsOne and not for test_TwoEqualsTwo.
I've seen other solutions on Stack Overflow:
Move the two test methods into different class [say this option is not possible for particulr scenario] (or)
JUnit: #Before only for some test methods? as described by this post
I can somehow use the test method name and skip over the execution of the rule
but a drawback of this approach would be, each time I use the rule in a specific class for a specific set of methods, I need to add all those method names to a list to see if they are found, to determine the execution of the rest of the logic.
Is there any way to use a custom rule in a test class for a particular set of test methods while ignoring them for the other test methods in the same test class?
For the best of my knowledge, #Rule applies to all tests. Therefore, if you need #Rule to be used in a single #Test method only, don't use #Rule. In that case, your code would look like this:
public class TestClassExample {
#Test
public void test_OneEqualsOne() {
CustomRuleForOneEqualsOne customRuleForOneEqualsOne = new CustomRuleForOneEqualsOne();
// use customRuleForOneEqualsOne
}
#Test
public void test_TwoEqualsTwo() {
assertEquals(2, 2);
}
}
I am a Dagger newbie.
TL;DR:
If an Android Service has any fields injected into it using Dagger, then in order to actually perform the injection, I need to have an instance of that Service.
In Robolectric tests, this corresponds to MyService service = Robolectric.buildService(MyService.class).get(). And then, objectGraph.inject(service);
However, rest of the code that actually starts MyService still uses context.startService(context, MyService.class);.
Question: What is the idiomatic way in Dagger to address this mismatch?
Let's say I have a Service as follows:
public class MyService {
#Inject Parser parser;
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
String data = intent.getStringExtra("data_to_be_parsed");
parser.parse(data);
}
}
Elsewhere in my code, I have an ApiClient class that does this:
public class ApiClient{
public static void parseInBackground(Context context, String data){
//This service does not have its fields injected
context.startService(new Intent(context, MyService.class).putExtra("data_to_be_parsed", data));
}
}
That parseInBackground method will be called from an Activity in response to user interaction.
Now, I'm following TDD and hence, I haven't yet written the Application Module for this. Here's the test module:
#Module(injects = MyService.class)
public class TestModule {
#Provides #Singleton Parser provideParser(){
return new MockParser();
}
}
And finally, the test case:
#RunWith(Robolectric.class)
public class ApiTest {
#Test
public void parseInBackground_ParsesCorrectly(){
//This service has its fields injected
MyService service = Robolectric.buildService(MyService.class).get();
ObjectGraph.create(new TestModule()).inject(service);
ApiClient.parseInBackground(Robolectric.application, "<user><name>droid</name></user>");
//Asserts here
}
}
As you can see, in the test, I retrieve an instance of the service and then inject the MockParser into it. However, the ApiClient class directly starts the service using an Intent. I don't have a chance to perform the injection.
I am aware that I can have MyService perform an injection on itself:
public void onCreate(){
ObjectGraph.create(new TestModule()).inject(this);
}
But then, I am hardcoding the TestModule here.
Is there an existing idiom in Dagger to set up dependencies for such situations?
It's the wrong way to hardcode your modules either in tests or in services. Better approach is to perform creation via your custom Application object which in turn will hold singleton ObjectGraph object. For example:
// in MyService class
#Override public void onCreate() {
super.onCreate();
MyApp.from(context).inject(this);
}
// in MyApp class
public static MyApp from(Context context) {
return (MyApp) context.getApplicationContext();
}
//...
private ObjectGraph objectGraph;
#Override public void onCreate() {
// Perform Injection
objectGraph = ObjectGraph.create(getModules());
objectGraph.inject(this);
}
public void inject(Object object) {
objectGraph.inject(object);
}
protected Object[] getModules() {
// return concrete modules based on build type or any other conditions.
}
Alternatively, you can refactor last method out into separate class and make different implementations for different flavors or build types. Also you may want to set overrides=true in your TestModule's annotation.
I am using PowerMock to mock static methods in junit tests, typically done as follows:
#RunWith(PowerMockRunner.class)
#PrepareForTest({Foo.class,Bar.class})
public class SomeUnitTest {
#Before
public void setUpTest() {
setUpFoo();
setUpBar();
}
private void setUpFoo() {
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private void setUpBar() {
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
#Test
public void someTestCase() {
...
}
}
This works fine, but I'm finding that specifying the #PrepareForTest annotation is preventing me from making my testing API flexible.
What I'd like to do is something like the following:
public class MockLibraryOne {
public static void setUpLibraryOne() {
setUpFoo();
setUpBar();
}
private static void setUpFoo() {
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private static void setUpBar() {
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
}
#RunWith(PowerMockRunner.class)
public class SomeUnitTest {
#Before
public void setUpTest() {
MockLibraryOne.setUpLibraryOne();
}
#Test
public void someTestCase() {
...
}
}
Here my unit test has a dependency on LibraryOne, but it does not know which classes LibraryOne depends on, so it does not know which classes to add to the #PrepareForTest annotation.
I could make SomeUnitTest extend MockLibraryOne and add the #PrepareForTest annotation to the MockLibraryOne class, but I will have dependencies on more than just MockLibraryOne in other unit tests, so inheritance is not a general solution.
Is there some way of programmatically preparing a class for testing under PowerMock, instead of using the #PrepareForTest annotation? For example, something like the following:
public class MockLibraryOne {
public static void setUpLibraryOne() {
setUpFoo();
setUpBar();
}
private static void setUpFoo() {
prepareForTest(Foo.class);
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private static void setUpBar() {
prepareForTest(Bar.class);
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
}
I guess it would be nice if PowerMockRunner processed the #PrepareForTest annotation a little differently: for each specified class, it should not only add that class (and its hierarchy) to the list of classes to prepare for mocking, but then examine that class to see if it has any #PrepareForTest annotations as well:
#RunWith(PowerMockRunner.class)
#PrepareForTest({MockLibraryOne.class})
public class SomeUnitTest {
...
}
#PrepareForTest({Foo.class,Bar.class})
public class MockLibraryOne {
...
}
}
So in this the #PrepareForTest annotation on SomeUnitTest would find MockLibraryOne, and the #PrepareForTest annotation there would drag in Foo.class and Bar.class as well.
So perhaps writing my own test runner to replace PowerMockRunner may be a solution.
Or perhaps there's a simpler solution, using PowerMockAgent class, for example?
edit: Mock Policies may be one solution: https://code.google.com/p/powermock/wiki/MockPolicies
edit: Mock Policies works with PowerMockRunner but not (it seems) with PowerMockRule (which I sometimes require due to class loader issues).
What you try to achieve will not work.
The problem is that powermock must rewrite the client class's code to intercept the static invocation and it can't do this after the class is loaded. Thus it can only prepare a class for test before it is loaded.
Let's assume you want to mock the System.currentTimeMillis invocation in the following simple class.
class SystemClock {
public long getTime() {
return System.currentTimeMillis();
}
}
Powermock will not change the code of java.lang.System.currentTimeMillis, because it can't. Instead it changes the SystemClock's byte code so that it does not invoke System.currentTimeMillis anymore. Instead it invokes some other object that belong to powermock.
This is how powermock get's full control over the return value and allows you to write a test like this:
#RunWith(PowerMockRunner.class)
#PrepareForTest({ SystemClock.class })
public class PowerMockitoTest {
#Test
public void systemTimeMillis() {
SystemClock systemClock = new SystemClock();
PowerMockito.mockStatic(System.class);
PowerMockito.when(System.currentTimeMillis()).thenReturn(12345L);
long time = systemClock.getTime();
assertEquals(12345L, time);
}
}
You can see that powermock has rewritten the client class in the stacktrace of your debugger. Set a breakpoint at SystemClock.getTime and step into the invoked method.
As you can see SystemClock invokes a MockGateway.
If you take a look at the variables on the stack of the MockGateway invocation, you can see how the original System.currentTimeMillis method is handled.
Perhaps you're looking for a mock policy?
Could you help this (taken from documentation)?
You can also prepare whole packages for test by using wildcards:
#PrepareForTest(fullyQualifiedNames="com.mypackage.*")
So you can add the whole library to your prepare...
Why do you even want to mock static methods? Why not wrap those static methods in a class that you can mock with mockito?
class FooWraper {
void someMethod() {
Foo.someStaticMethod()
}
}
and then you can create a mock of your FooWraper. No need to use Powermock at all...
I have a public method that uses a local private method to get data from the Db.
private string SomeMethod(string)
{
...
Doing some operations
...
string data = GetDBData(string);
Doing some operations
...
}
I want to divert/isolate the private method GetDBData(string) using moles so my test will not require the DB.
Obviously, my question is: how to do it?
thank you
Uria
EDIT
Additional information:
i tried to change the method accessors both to public and internal protected,
in both cases i can now see the methods as moles.
BUT when running the test, the original method is still being used and not the detour I've implemented in the PexMethod.
You can try any of the following.
Make the method internal and add an attribute like this to the assembly:
[assembly: InternalsVisibleTo("<corresponding-moles-assembly-name>")]
Change the method access to protected virtual and then use a stub.
Refactor your class so that it gets an interface (IDataAccessObject) as a constructor parameter, SomeMethod being one of the methods of that interface, and then pass a stub of that interface to your class in test methods.
I figured it out
If i have the public MyClass with private SomeMethod
public class MyClass
{
private string SomeMethod(string str){}
}
if you want to mole the SomeMethod method you need to use AllInstances in the test method:
[PexMethod]
SomeMethod(string str)
{
MMyClass.AllInstances.SomeMethod = (instance, str) => { return "A return string"; };
}
notice that the lambda receives an instance parameter as the first parameter. I'm not sure what it's function is.
I'm trying to start using Unit Testing on my current project in Visual Studio 2010. My class structure, however, contains a number of interface and abstract class inheritance relationships.
If two classes are derived from the same abstract class, or interface I'd like to be able to share the testing code between them. I'm not sure how to do this exactly. I'm thinking I create a test class for each interface I want to test, but I'm not sure the correct way to feed my concrete classes into the applicable unit tests.
Update
OK here's an example. Say I have an interface IEmployee , which is implemented by an abstract class Employee, which is then inherited by the two concrete classes Worker and Employee. (Code show below)
Now say I want to create tests that apply to all IEmployees or Employees. Or alternatively create specific tests for specific types of Employees. For example I may want to assert that setting IEmployee.Number to a number less then zero for any implementation of IEmployee throws an exception. I'd prefer to write the tests from the perspective of any IEmployee and then be able to use the tests on any implementation of IEmployee.
Here's another example. I may also want to assert that setting the vacation time for any employee to a value less then zero throws and error. Yet I may also want to have different tests that apply to a specific concrete version of Employee. Say I want to test that Worker throws an exception if they are provided more then 14 days vacation, but a manager can be provided up to 36.
public interface IEmployee
{
string Name {get; set;}
int Number {get; set;}
}
public abstract class Employee:IEmploee
{
string Name {get; set;}
int Number {get;set;}
public abstract int VacationTime(get; set;)
}
public abstract class Worker:IEmployee
{
private int v;
private int vTime;
public abstract int VacationTime
{
get
{
return VTime;
}
set
{
if(value>36) throw new ArgumentException("Exceeded allowed vaction");
if(value<0)throw new ArgumentException("Vacation time must be >0");
vTime= value;
}
}
public void DoSomWork()
{
//Work
}
}
public abstract class Manager:IEmployee
{
public abstract int VacationTime
{
get
{
return VTime;
}
set
{
if(value>14) throw new ArgumentException("Exceeded allowed vaction");
if(value<0)throw new ArgumentException("Vacation time must be >0");
vTime= value;
}
}
public void DoSomeManaging()
{
//manage
}
}
So I guess what I'm looking for is a work flow that will allow me to nest unit tests. So for example when I test the Manager class I want to first test that it passes the Employee and IEmployee tests, and then test specific members such as DoSomeManaging().
I guess I know what you mean. I had the same issue.
My solution was to create a hierarchy also for testing. I'll use the same example you show.
First, have an abstract test class for the base IEmployee.
It has two main things:
i. All the test methods you want.
ii. An abstract method that returns the desired instance of the IEmployee.
[TestClass()]
public abstract class IEmployeeTests
{
protected abstract GetIEmployeeInstance();
[TestMethod()]
public void TestMethod1()
{
IEmployee target = GetIEmployeeInstance();
// do your IEmployee test here
}
}
Second, you have a test class for each implementation of IEmployee, implementing the abstract method and providing appropriate instances of IEmployee.
[TestClass()]
public class WorkerTests : IEmployeeTests
{
protected override GetIEmployeeInstance()
{
return new Worker();
}
}
[TestClass()]
public class ManagerTests : IEmployeeTests
{
protected override GetIEmployeeInstance()
{
return new Manager();
}
}
You can see everything works as expected and VS gives you the expected test methods for each WorkerTests and ManagerTests classes in the TestView window.
You can run them and have the test results for each implementation of the IEmployee interface, having to create the tests only in the base IEmployeeTests class.
You can always add specific test for the derived WorkerTests and ManagerTests classes.
The question would be now, what about classes that implement multiple interfaces, let's say EmployedProgrammer?
public EmployedProgrammer : IEmployee, IProgrammer
{
}
We don't have multiple inheritance in C#, so this is not an option:
[TestClass()]
public EmployedProgrammerIEmployeeTests : IEmployeeTests, IProgrammerTests
{
// this doesn't compile as IEmployeeTests, IProgrammerTests are classes, not interfaces
}
For this scenario, a solution is to have the following test classes:
[TestClass()]
public EmployedProgrammerIEmployeeTests : IEmployeeTests
{
protected override GetIEmployeeInstance()
{
return new EmployedProgrammer();
}
}
[TestClass()]
public EmployedProgrammerIProgrammerTests : IProgrammerTests
{
protected override GetIProgrammerInstance()
{
return new EmployedProgrammer();
}
}
with
[TestClass()]
public abstract class IProgrammerTests
{
protected abstract GetIProgrammerInstance();
[TestMethod()]
public void TestMethod1()
{
IProgrammer target = GetIProgrammerInstance();
// do your IProgrammerTest test here
}
}
I'm using this with good results.
Hope it helps.
Regards,
Jose
What I think you want to do is create unit tests for methods in abstract classes.
I'm not sure it makes sense to want to test a protected method on an abstract class, but if you insist simply extend the class in a class used exclusively for unittesting. That way you can expose the protected methods on the abstract class you want to test through public methods on the extending class that simply call through to the method on the abstract class.
If you have methods in abstract classes that you want unittested, I suggest refactoring them into separate classes and simply expose them as public methods and put those under test. Try looking at your inheritance tree from a 'test-first' perspective and I'm pretty sure you'll come up with that solution (or a similar one) as well.
It seems that you have described "composite unit testing" which is not supported by Visual Studio 2010 unit tests. Such things can be done in MbUnit according to this article. It is possible to create abstract tests in Visual Studio 2010 which is probably not exactly what you want. Here is description how to implement abstract tests in VS (Inheritance Example section).
Use microsoft moles for better testing. so you can mock the abstract base class / static methods etc easily. Please refer the following post for more info
detouring-abstract-base-classes-using-moles
BenzCar benzCar = new BenzCar();
new MCar(benzCar)
{
Drive= () => "Testing"
}.InstanceBehavior = MoleBehaviors.Fallthrough;
var hello = child.Drive();
Assert.AreEqual("Benz Car driving. Testing", hello);
The desire to run the same test against multiple classes usually means you have an opportunity to extract the behavior you want to test into a single class (whether it's the base class or an entirely new class you compose into your existing classes).
Consider your example: instead of implementing vacation limits in Worker and Manager, add a new member variable to Employee, 'MaximumVacationDays', implement the limit in the employee class' setter, and check the limit there:
abstract class Employee {
private int maximumVacationDays;
protected Employee(int maximumVacationDays) {
this.maximumVacationDays = maximumVacationDays
}
public int VacationDays {
set {
if (value > maximumVacationDays)
throw new ArgumentException("Exceeded maximum vacation");
}
}
}
class Worker: Employee {
public Worker(): Employee(14) {}
}
class Manager: Employee {
public Manager(): Employee(36) {}
}
Now you have only one method to test and less code to maintain.