Different mocks are used for @Mock and @InjectMock when using @TestInstance(TestInstance.Lifecycle.PER_CLASS) of jUnit5

Hi,

I have a problem which seems to be very similar to this one https://github.com/mockito/mockito/issues/1346 but it is happening when I run test with @TestInstance(TestInstance.Lifecycle.PER_CLASS) (which is a better thing to do in Kotlin).

For the following code, the first iteration is working and the following are not because the behavior of another mock is changed 😰(foo.bar isn’t the same as bar)

class Bar {
    fun call() = 42
}

class Foo(val bar: Bar) {
    fun call() = bar.call() + 23
}

@TestInstance(TestInstance.Lifecycle.PER_CLASS) // If this is remove, all is ok
@ExtendWith(MockitoExtension::class)
class HelloTest {

    @Mock lateinit var bar: Bar
    @InjectMocks lateinit var foo: Foo

    @RepeatedTest(4)
    fun `should return 24`() {
        /* Given */
        whenever(bar.call()).thenReturn(1)
        /* When */
        val r = foo.call()
        /* Then */
        assertThat(r).isEqualTo(24)
    }

    @RepeatedTest(4)
    fun `@InjectMocked foo should have same bar as bar`() {
        assertThat(foo.bar).isSameAs(bar)
    }
}

We can also see this in the IDE :

First time:

Second time:

Of course, if I remove the @TestInstance(TestInstance.Lifecycle.PER_CLASS), all is now OK.

I’m running on the last version 2.19.1 with jUnit 5.2.0. You can see the full example here :

https://github.com/davinkevin/issue-mockito-junit5-kotlin

[vghero]

Hey, today we also ran into this, being confused why it works for the test in isolation but not when running all test together. Then we saw that setting @TestInstance(TestInstance.Lifecycle.PER_METHOD) makes it work. Finally ending up here. Is there any progress on this? We also have just ctor injection and in there we set the value into a final field. So code-wise it’s a common case. Also if not fixable in the near future, should Mockito better fail on such situations (if detectable) or at least adding a hint to @InjectMocks javadoc could help?

[slawekjaranowski]

Last time I did some refresh and refactor in mockito-testng project.

Now mockito-testng simply call Mockito.mockitoSession()....startMocking();

There are no any manual management for mocks and other injections.

TestNG has by design one instance of test class.

In similar case @InjectMocks inject correct mock into annotated class.

One case where class with @InjectMocks has old value is when we have class with constructor and value is stored in final field.

final field are not refreshed before next test.

Another workaround can be set null to field which should have injected mock in some of after method, so class will be created with corrected injections.