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Frequently Asked Questions
1. How to mock the fields initialized by @Autowired in the class under test?
Create the class under test object directly, and then use the ability of TestableMock to access private members to directly assign values to these fields.
2. Can TestableMock be used with other mock tools?
TestableMock can be safely used together with other mock tools based on dynamic proxy mechanism, such as Mockito, EasyMock, Spock, etc., all belong to this category.
For mock tools that modify the class loader or the bytecode of the class under test, such as PowerMock and JMockit, there is no yet case to prove that they will conflict with TestableMock, but in principle, there may be a risk of incompatibility between the two, Please use with caution.
3. Which test frameworks does TestableMock support?
The PrivateAccessor / OmniConstructor / OmniAccessor and basic functionality of TestableMock are theoretically test-frameworks-independent, and should work with any test frameworks out-of-box.
The only test-framework-related part is the mock invocation verifier, which currently supports JUnit 4 / JUnit 5 / TestNG and Spock appropriately.
If you encounter compatibility problem under a specific test framework, or want to add mock invocation verifier support for any other frameworks, please raise an issue to tell us.
4. How to implement the mock method when the parent class variable points to the child class object?
In the code, there are often cases of using interface variables or parent class variables to point to an instance of subclasses and calling methods provided by the parent class or subclass.
At this time, follow a principle that the type of the first parameter of the mock method is always the same as the type of the variable that initiated the call.
Therefore, regardless of whether the actually called method comes from the parent class or the subclass, and whether the subclass overrides the method. If the calling variable is of the parent type (or interface type), the first parameter type of the mock method should use the corresponding parent type (or interface) type.
See the use case of the DemoInheritTest test class in the Java and Kotlin examples.
5. How to mock generic methods (template methods)?
Just use the same generic parameters directly on the mock method.
See the use case of the DemoTemplateTest test class in the Java and Kotlin examples.
Because JVM has a generic erasure mechanism, you can also directly use the
Objecttype to replace generic parameters for Java projects, see the commented out "Second solution" example in the Java version of theDemoTemplateTesttest class.
6. How to mock invocation inside an inner class?
Just put mock methods in the mock container class of its outer class, it works for code in all inner classes.
See the use case of the DemoInnerClass test class in the Java and Kotlin examples.
7. Why mocking methods in the String class in the Kotlin project does not work?
The String type in Kotlin language is actually kotlin.String instead of java.lang.String. However, when this type is built from bytecode, it will be replaced with Java's java.lang.String class, so no matter if the mock target is written as kotlin.String or java.lang.String, it cannot match the original called method.
In actual scenarios, there are very few scenarios where methods in the String class need to be mocked, so TestableMock has not dealt with this situation specifically.
8. Can TestableMock be used for testing Android projects?
It can be used in combination with Roboelectric testing framework.
The Dalvik and ART virtual machines of the Android system use a bytecode system different from the standard JVM, which will affect the normal functionality of TestableMock. The Roboelectric framework can run Android unit tests on a standard JVM virtual machine, which is much faster than running unit tests through the Android virtual machine. Recently, most Android App unit tests are written with the Roboelectric framework.
9. Meet "Command Line is too Long. Shorten command line for ..." error when triggering test in IntelliJ IDE?
This problem is caused by the system Class Path content is too long, and has nothing to do with TestableMock. However, it should be noted that IntelliJ provides two auxiliary solutions: JAR manifest and classpath file. If TestableMock is used in the test, please select JAR manifest.
