@InjectMocks ignores @Mock's name of generic type

When injecting two fields of the same type with @InjectMocks, the @Mock’s name is not taken into account.

public class Foo {
    Bar<Integer> f1;
    Bar<Boolean> f2;

    public Foo(Bar<Integer> f1, Bar<Boolean> f2) {
        this.f1 = f1;
        this.f2 = f2;
    }
}

interface Bar<T> {
}

@RunWith(MockitoJUnitRunner.class)
public class FooTest {

    @Mock(name = "f1")
    Bar<Integer> f1;

    @Mock(name = "f2")
    Bar<Boolean> f2;

    @InjectMocks
    Foo foo;

    @Test
    public void test() {
        System.out.println(foo.f1);
        System.out.println(foo.f2);
    }
}

Expected result: f1 mock --> f1, and f2 mock --> f2. Actual result: f1 mock is getting injected into both fields.

Version: mockito-core:2.7.22

[ChristianSchwarz]

Indeed it would be nice if Mockito would support construtor injection by parameter name! Constructor injection is different beast that field injection. For field injection the name of the target field can be used to match to the mock of the same name. For parameters this is not always possible, it depends on how the code was compiled and on the java version that run the code:

• till Java 8 there was no API to retrieve the parameter name, all parameters are named “arg0”,arg1",…
• It is possible retrive the name via ASM in case the code was compiled with debug infos otherwise it returns the “argN”-pattern , Spring does it in there LocalVariableTableParameterNameDiscoverer
• in Java 8 Executable.getParameters was introduced, that allow to retrieve the parameter name with limitations:

Method Parameter Reflection (RFE: JDK-8004841): You can obtain the names of the formal parameters of any method or constructor with the method java.lang.reflect.Executable.getParameters. However, .class files do not store formal parameter names by default. To store formal parameter names in a particular .class file, and thus enable the Reflection API to retrieve formal parameter names, compile the source file with the -parameters option of the javac compiler.

---

Long story short: It is possibe to implement construtor injection via parameter names. But your tests may break if they are not compiled or run with the same setup.

This limitation should be documented. A workaround would be to name the mock “argN” to indicate the parameter index for injection, but this has many other downsides.

[ubhide]

Just to keep this bug alive, I am definitely having this issue in v1.10.19

My workaround was to not use InjectMocks and create the object manually in the setup. Kinda messy but it gets around this issue.