mockito mock private method without powermock

When users run Unit-Test on there local machine they will get the famous "Method not mocked" exception. E.g: I can see for myself that we add something like: mockStatic is already overloaded, I would like to avoid another overload to keep it synchronous with mock. I search this question on stack overflow, someone suggested me using powermockito, but I'm working on Junit5, which is not compatible with Junit5. The OP asked if you could mock() instead of spy(), and the answer is YES: you could do that to solve the same problem potentially. There has been talk about the temporal scope of the static mock, but I think that consideration also needs to be given to the caller scope: which classes will see the mocked method and which will see the original. Please, consider the legacy code issue. Should we also send out a Tweet to gather some community insights? ", returnValue); A similar process is applied to the private method. Mockito ... and Powermock. In most cases there isn’t time in current hectic agile world to make such class easy to unit test standard way. Also, Java 8 method references make a lot of sense in this context. The MockedStatic approach don't give you guarantees if the user doesn't use try-with resource like this: The mocking/stubbing/verifing will work as expected but leaves the Class in a mocked state. It's like "oooh, your code is using statics, so it can't be tested with Mockito". Dex method limit is not a huge problem anymore because now there is native platform support for multidex apps. Does it use the same set of dependencies and only those? As an exercise from time to time I'm trying to answer PowerMock questions on StackOverflow. We can always try it out with the new artifact and discontinue it later if it is significantly misused. The OP asked if you could mock() instead of spy(), and the answer is YES: you could do that to solve the same problem potentially. The access level modifier is omitted, so it is ‘protected’ by default. With Mockito, you cannot mock private method calls. @raphw glad you took some inspiration and motivation out of my attempt. They are many workarounds for this issue like PowerMock or Roboelectric. But sometimes we want to call it directly, for example in unit testing. : The Android SDK provides many static utility methods with classes like TextUtils. In my opinion, I shouldn't need to do that to test my code's ability to properly read some file. For stub methods call verification, use PowerMock.verify() method.. EasyMock Private Method – JUnit 4. Than it is possible to mock it standard way. PowerMock is not stable state to be used with Mockito 2. It is true that there are workarounds - someone wrote: "Every problem can be solved with a layer of abstraction" - but then there is the corollary that seems to be forgotten: "...except for the problem of too many layers of abstraction." After this refactoring, private method in TC becomes public in new dependency class. I still think we leave it out of the first version and consider it for later. In Mock JUnit tests with Mockito example post, I have shown how and why to use Mockito java mocking framework to create good unit tests. Before 3.4.0, Mockito could not mock static methods. @raphw I know I am a little late to the party. If you continue to use this site we will assume that you are happy with it. So, we will need to mock this private method. Required fields are marked *. We’ll occasionally send you account related emails. thenAnswer patterns In order to enable Mock and Spy injections, the service, which will inject them, has to be defined with the @InjectMock annotation I think at least that introducing it into the standard API should be another ticket, if accepted. Great feedback. I had quick look into your branch, looks like you are going full steam ahead. Consider moving this logic to TC or to separate module. PowerMock is a JUnit extension the leverages the possibilities of EasyMock and Mockito to mock static methods (and much more). Othewise, why did you provide private method mocking in the recent versions athough it's considered as a "bad" practice for TDD purists ? 4. I am not currently in a position to spend so much time to build this component, due to my personal situation, but please prototype away. The biggest downside of offering static mocking is making it too easy to test crappy, procedural code full of static methods. You don't even need to create any additional classes. This incentives Mockito to solve static mocking, if users opt-in for it. It's not perfect solution, but is educational - shows developers that writing too complex static util methods hurts and makes code hard to test. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Find easier to mock boundaries for your integration test (you can find a clue in unit test for NDDC if exists). Personally, I am for clean tests and therefore consider static mocking very bad practice. Well structured Android app do not need mocking static methods, nor Roboelectric. The scope meant to automatically reset the static mock after usage, right? System.currentTimeMillis() is a classic example - there's no good way to reliably simulate code running at different system times without mocking this static method (you can use wrappers in your own code, but there's no guarantee that all the 3rd-party libraries you might want to use will). The text was updated successfully, but these errors were encountered: I am torn on this one. That's why I fully agree with @karollewandowski . There is no way to escape the scope. spy() is used when you want the real code of the class you are spying on to do its job, but be able to intercept method calls and return values. Book Review: Mastering Unit Testing Using Mockito and JUnit - Lubos Krnac, Package by layer for Spring project is obsolete, Aggregate Test Coverage Report for Gradle Multi-Module Project, Select Video.js subtitle track automatically, class that is not direct dependency of testing module. It wouldn't be a good idea to mock (eg). One of the challenges of unit testing is mocking private methods. If at least one is a "No" consider the alternatives: I agree with most of you and think that mocking static methods is not a good idea. It extends the existing mocking frameworks, such as EasyMock and Mockito, to add even more powerful features to them.PowerMock enables us to write good unit tests for even the most untestable code. You can decide later if integration test is needed for group of modules you trying to test. PowerMock is an open-source Java framework used for creating a mock object in unit testing. JBehave, JGiven for BDD style .... Then you can write all your testing stuf in Groovy and you only need ... Spock. That is why I decided to create and share refactoring considerations alongside with examples and workarounds for unusual mocking. Mock private method Refactoring considerations. solutions such as PowerMock". I'd say that the divide is between people who want to design their code properly and those who want to take the path of least resistance. It can really add a lot of confusion since not everybody expects it, for example when adjusting a build script. This would be useful, for example, for implementing spies in a situation like: With Mockito, I would like to see something like: What do you think? Unless I’m mistaken, the Mockito example’s are not private. Obviously yes; you could make a IFiles interface and then make a JREFilesImpl that passes the calls through to the static methods. Additionally, it is sometimes just not feasible to refactor code. It extends other mocking frameworks such as EasyMock and Mockito to enhance the capabilities. In the case of mocking statics, it is certainly possible to get around this problem (to an extent) by adding a new layer of abstraction - but this adds complexity. You can simply do: in a JUnit test when using the rule or extension and the same works in JUnit 5's extension for method parameters. I would like to be able to mock a private method in my code without actually invoking that private method during testing. If required users can call resetStatic(Class) in the test. Let’s say we’d like to test the “methodToTest” in isolation from the private “methodToMock” method … java - only - How to mock static method without powermock spring boot mock static method (2) (I assume you can use Mockito though) Nothing dedicated comes to my mind but i tend to use following strategy when it comes to situations like that: That's the first thing to figure out when working on this ticket :). As well, we should only use it in a test class. Through mocking you can explicitly define the return value of methods without actually executing the steps of the method. @ChristianSchwarz I do not agree, using Android static utils or Android framework in your business logic is a bad smell. Some of it was new code written by an inexperienced team (of which I was part of) and knowing that Mockito devs disapproved of our design patterns probably wouldn't have made any difference. We should probably find a better solution for this, potentially in Mockito 3. This extends Part 3: Mockito partially mocking with @Spy by making the method “processUser(int id)” as a private method. The first test testInitialize() behaves like any other Mockito test with the exception that we mock it using PowerMockito.mockStatic(IdentityUtilities.class) to initialize it. @dbacinski, I am not an expert on Android so bear with me, please :) Adding extra layer introduces more method calls which can be problematic on large apps that hit dex method limit, right? PowerMock has method . If the private method is in NDDC, you are probably creating integration test instead of unit test. Successfully merging a pull request may close this issue. Examples are using Mockito and PowerMock mocking frameworks and TestNG unit testing framework. Mockito#mock; I will share not only the source code, but also their advantage and inconvenience. PowerMock doesn’t support JUnit 5 as of now, so I will use JUnit 4 for writing test cases. (PowerMock indeed wraps the reflection for you) You can find the source code for this Mockito example on Github. So +1 for the ability to mock static methods. junit,mockito,powermock,easymock,powermockito. This site uses Akismet to reduce spam. One sidenote: putting everything in a new artifact would scatter the mockito ecosystem. I had asked about this at some point in the past and was told it was being considered. I was worried that such examples without any guidance can be widely used by teammates not deeply experienced in mocking frameworks. No mocking – In theory, static methods should be used only in small utility classes. Does mocking static methods fall nicely into the current design? Although we might need to mock private method to dissociate from whatever it does, all the complexity, just use an output it … It could only mock non-static methods. Also, for now, we're using Powermock as a workaround for this need but it's not compliant with the last versions of Mockito. This is a placeholder ticket for enabling mocking static methods in Mockito. When you are trying to unit test such class you often realize that unusual mocking is needed. If we would return a special interaction method, where you later have to call close() yourself, then you can assign this to any variable/field and make it longlived. +1. Though, PowerMock could. Therefore, for me, one requirement for static method mocking is that it is explicitly limited to scope and can't escape that scope. Private method that is needed to be mocked can be in: This is my preferred technique when I need to mock private method. You can pass, a) a path that exists - to test the positive scenario Once it's there in the library users will require it to be there. However Junit would not allow me to write a test case for a private method. Thank Rafael you for the constuctive discussion and considering other opinions and approches. Not all of the code we were using PowerMock for was legacy. Mocking static method with Mockito in older versions 2.x. (Not to mention that some people would like to have nice unclebobish tests but aren't allowed to refactor the code they have to maintain. Why shall I do it – its private, not exposed and tend to change or disappear at all during some code refactoring. Either it's there or not. I think we all agree that mocking statics is a bad practice and an anti-pattern in general. The Android community would like mock static methods, well at least me. That means to mock all direct dependencies (sometimes it’s easier to test with real objects when they are simple and independent enough). Hi Rafael, I like the scoping of the mock via Closable interface. I think for now, we leave it this way; it would however not be difficult to add a MockSettings option to include additional threads or to even make the mock global. Therefore, I would vouch for a different artifact (probably called mockito-legacy), which offers static mocking. @szczepiq you are right that you need additional methods to abstract Android apis, but this is a cost of good architecture. Static members aren't something good, I hope it's quite obvious. The use of static methods in Java can be seen as somewhat controversial. offer the feature). In my current project we used to use PowerMockito to mock static methods and after some time our tests started to fail because of concurrency issues: We ended up with wrapping static methods in injectable objects and removed PowerMockito from project dependencies. However, the workaround could be cumbersome and can spoil the clarity of codebase. expacted behavior is donothing when calling getService(), but when I debug my code, is still go into the method getService(), so I'm wondering if there is anyway to mock a static method with Mockito. powermock-api-mockito2: This is the core PowerMock dependency and used to extend Mockito2 mocking framework. Either the code is not yours or you cannot change a legacy code base (immediately). Sign in This document presents two Maven example projects for mocking final and static methods using PowerMockito for Java unit testing. Do you want to support a double tool in the long term? Static methods mocking with Mockito. PowerMock integrates with mocking frameworks like EasyMock and Mockito and is meant to add additional functionality to these – such as mocking private methods, final classes, and final methods,etc. We would remove a motivation to refactor the code into clean OO / DI. Thanks @raphw for that and glad to see some progress on it. It could only mock non-static methods. Also we can mock selected method of object with PowerMock.createPartialMock(ClassUnderTest.class, methodName) and it works for simple private … But that's a bunch of extra effort, it adds complexity to your code, and obscures the methods that are actually being called. Refactor NDDC according refactoring practises mentioned for TC and DDC above, update it’s unit test (also all tests affected by refactoring), and use created public method as boundary for your integration test. So far in my blog, I have written a lot for PowerMock. It's fully working and I am only waiting for the Mockito team members to return from their vacations to get some feedback from them before merging. In these cases, it is very convenient to have the possibility to mock static methods, also to give you safety if you are changing code in intermediate steps to finally remove them. It does that by relying on bytecod… Some people are willing to experiment together with you, others will be pissed off when you quit support after they have heavily used it. Having the construct available for example allows for the use in Junit extensions and rules. spy() is used when you want the real code of the class you are spying on to do its job, but be able to intercept method calls and return values. Replacing Mockito.mockStatic(klass, () -> { … }) with the fluent Mockito.mockStatic(klass).scope(() -> { … }) may look nice (to others, not necessarily to me :-)), but then the compiler won't complain when the scope is missing. Your response a) does not address the call to readAllLines(), and b) does not address either of the issues I raised in #1013 (comment), @rdicroce I haven't explicitly but the answer is simple. We're blocked with 1.9.x version of Mockito. Even though I inherently disagree with static mocking, I think it is only fair that we as Mockito developers offer users the option to opt-in a less intrusive and upgrade-compatible solution. Developers practicing TDD or BDD should be aware of testability problems behind these constructs and try to avoid them when designing their tests and modules. That is the reason why you probably wouldn’t be facing such unusual mocking often on project using these great programming methodologies. This is a placeholder ticket for enabling mocking static methods in Mockito. I'm thinking here in particular the case of mocking methods of common classes (eg, JDK classes) that might also be in use by the test framework. Example #2 – Mock private methods (partial mocking) Partial mocking of both static and instance methods works in PowerMock regardless if the method or class is final or private. However, In JUnit 5, the annotation @ExtendWith is repeatable, so you can use it without worrying about the exclusivity.. After each test case, Mockito extension validates the framework state to detect invalid use of Mockito. spy() and mock() are two different things. Changing private access modifier to default, Partially mock testing object by using spy, Mocking of changed default method with return value, Mocking of changed changed default void method, Verifying of changed default method calls, Mocking of private method with return value. Examples are using Mockito and PowerMock mocking frameworks and TestNG unit testing framework. spy() and mock() are two different things. Java actually provides ways to call private method with the help of reflection, java.lang.reflect.Method PowerMock, a widely used mock library also provide helper class to make it easy in JUnit test cases. Before usage of this example, please carefully consider if it is worth to bring bytecode  manipulation risks into your project. Alternatively, you can use Mockito to do steps #2 & #3 for you, if you’ve done step #1 already. . It helped me to put the last bits of the puzzle on its place. We may often decide the trade-off is worth it to make our code testable, but wouldn't it be better if you didn't have to make the trade-off? It doesn't seem like the real private method should be invoked at all. If you could mock statics without paying the price of adding an extra level of indirection? After that, use PowerMock.expectPrivate() method to stub the private method behavior.. Make sure to call PowerMock.replay() before writing the test code that uses the stubbed methods. The main use cases for mocking statics I see are: Without addressing above 2 use cases, developers around the world will be looking for help in tools like Powermockito, and such. I realize the latter is an esoteric use case, but I actually am working on a project that is developed on Windows but runs exclusively on Linux. When you use the lambda you will be safe, the static mock will only life in the scope of the lambda. The private methods are designed not accessible from outside. Most of the mocking frameworks in Java cannot mock static methods or final classes. Every time a developer uses this feature, it should be very explicit that it is bad practice imo. Not sure if I like the lambda syntax. We don't want the real HTTP request made for the unit test. You signed in with another tab or window. Mockito alone cannot stub this method, that is why we have used PowerMock along with Mockito. How to mock a void private method to throw Abstract Exception with Powermock? Feedback welcome! I think the recurring theme right now is: either you are pro or you are strictly against it. Mocking multiple classes for static methods is fully possible: The only thing that is not allowed is to mock the same class twice but Mockito will detect this and throw an exception. It was not a repeatable annotation. The downside is that there implementation is only provided on the device or emulator. @rdicroce I completely disagree with this statement: You could via a constructor inject myFilePath to point to your test resources. Prerequisites. It's another good reason to get this feature: Limit dependencies. I suggest we stick to it for the first release. What always bothered me about static mocks was their potential inferrence with parallel test cases and so forth, but all of this is solvable. In my opinion in general testing static methods is a bad idea and it would be better to refactor the code, however, sometimes it's something that is needed. In my opinion it should be used only in very rare and non-avoidable cases. The question I often ask to those people is "Why are you doing this?". Given that these users opt for such solutions signals that the other solution would be no tests at all, and that is probably what we would never want. The "test1" method initiated a Mockito mock for the "RegularClass" and assigned it to the instance variable "instance"; The "test2" simply uses the "instance" for the testing without re-initiating the mock. If you want to force a scope, please make it a parameter of (all overloaded) mockStatic. I used to work on several large codebases that made extensive use of static methods and used PowerMock (and PowerMockito) heavily for testing. Have fun mocking static method calls with Mockito, Philip In the end, no matter which outcome, there will always be disappointed developers. I'll clean it up and add documentation. One project is for JUnit, the other project is for TestNG.. Background. This also allows to simplify futher by obmitting the try-with-resource. Download JUnit Example Download TestNG Example. March 22, 2010 Introduction. I was asked to put together examples how to mock Java constructs well know for their testability issues: I am calling these techniques unusual mocking. Try PowerMockito with which you can mock any kinds of methods like static methods, private methods, local method instantiations and so on. Using @MockitoJUnitRunner means you cannot use other runners anymore. If the explicit model is used and the mock is not closed, it is currently unsafe. The following output shows that the test is successfully running using PowerMock with Mockito. Or does it work out the the same thing (w/ the Java compiler handing Mockito a Function to mock, either way)? and i shouldn't mention other peripheral libraries: privacy statement. After this refactoring, private method in TC becomes public in new dependency class. Simplicity should be a goal of code - we shouldn't add complexity without good reason, and layers of abstraction add complexity at all levels (in development and at runtime). If the private method is in TC, it is a good sign that TC has low cohesion (has too many responsibilities) and logic behind private method should be extracted into separate class. When “privateMethod” is called with whatever object then return mockPoint which is actually a mocked … Evidence yet again we can be lucky we have you on our side working on these problems . Then you can map the Dummy.class to the corresponding MockedStatic object. You can use java reflection to access private fields in test classes. Is this possible? I wanted to write test cases for both the method. Also, adding a layer of abstraction is only possible in code that I have control over. Mockito is really a nice framework. ex: ReflectionUtils.setField(status, this.myClass, true); Your email address will not be published. Mockito.mockStatic(Dummy.class).scope(() -> { ... }); The mock is generated when you call the scope(..) method, then the lambda/scope is executed.After that the mock will be closed/reset. I search this question on stack overflow, someone suggested me using powermockito, but I'm working on Junit5, which is not compatible with Junit5. I put the working prototype on a branch and suggest this API: https://github.com/mockito/mockito/blob/static-mock/subprojects/inline/src/test/java/org/mockitoinline/StaticMockTest.java. Answer the following questions (to yourself): If you answer all 3 with "Yes", then go ahead. You can however easily mock Instant.now(). You'll have to support that feature etc. But PowerMock did it slowly: it replaced a classloader for every test, and executed the whole test within this classloader. Than it is possible to mock it standard way. Their functionality should be simple enough. Rarely should you call static methods directly and if you do, most likely these are utils that you don't want to stub. You should encapsulate the logic of a static method in an object that makes business sense to use it. I also adjusted the JUnit integration to make the ceremony superfluous. DBUnit, This annotation is a shorthand for the Mockito.mock() method. Well, in my opinion file name/path from your example is good candidate for passing it to method/setter/constructor instead of hardcoding it and you can just create test file in filesystem. The test framework will rely on the normal behaviour of the mocked class while you will want the class-under-test (and its dependencies) to see the mocked behaviour. @TimvdLippe you're mentioning this " However, our users apparently have usecases that require (intrusive?) What if I am testing a larger component that runs code in multiple threads, how to do that? For instance, testing a default method given() in mockito-java8 interface delegating to a static method in BDDMockito.given() the easiest solution I see is to generate in runtime a list of static methods in BDDMockito and execute parameterized test for every of them verifying that a corresponding method in WithBDDMockito interface delegates to it with proper parameters. the way I saw mocking of static methods for myself was to only mock calls to static methods that happen within a mock. Please! I.e. If you want to read a file using that API, you might do something like: Now, is there a way to test this without mocking static methods? Finally note that Mockito forbids mocking the static methods of System (and Thread). The refactored example should give you valuable hints on how to work around mocking static calls. If you want to test view layer then go with Instrumentation tests and Espresso. Not sure if I like the lambda syntax. Graceful. to your account. The try-solution addresses this point, but the lambda return call does not. I’m using JUnit 4 with Mockito 2.28.2. The mocking of the private method is done with following code: PowerMockito.doReturn(mockPoint).when(powerMockDemoSpy, “privateMethod”, anyObject()). Examples are using Mockito and PowerMock mocking frameworks and TestNG unit testing framework. You can have a look at my open PRs if you want to give it a test run. We can always iterate based on feedback :). Talking about the scope: An other option is to enable static mocks via@StaticMock or staticMock(Class) and then reset/disable them automatically after each test.

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