I'm struggling with providing instances of Beans for SpringBoot tests, can anyone see what I'm doing...

# spring

[dr.dreigh]

I'm struggling with providing instances of Beans for SpringBoot tests, can anyone see what I'm doing wrong please:

@SpringBootApplication
class DemoApplication

fun main(args: Array<String>) {
    runApplication<DemoApplication>(*args)
}

@Component
class NormalComponent() {
    fun value() = "Hi"
}

Test:

@TestConfiguration
class TestConfig {

	@Bean
	fun normalComponentMock(): NormalComponent {
		val mock =  mock(NormalComponent::class.java)
		`when`(mock.value()).thenReturn("I AM A MOCK!")
		return mock
	}
}

@SpringBootTest
@Import(TestConfig::class)
class DemoApplicationTests(
	@Autowired val norm: NormalComponent
) {
	@Test
	fun normInjectedIntoTest() {
		assertEquals("I AM A MOCK!", norm.value())
	}
}

The error:

org.junit.jupiter.api.extension.ParameterResolutionException: Failed to resolve parameter [com.example.demo.NormalComponent norm] in constructor [public com.example.demo.DemoApplicationTests(com.example.demo.NormalComponent)]: No qualifying bean of type 'com.example.demo.NormalComponent' available: expected single matching bean but found 2: normalComponent,normalComponentMock

I know I could use @MockBean - this is just a simple example where the bean I want to inject to the instance.

Bit confused why the mock conflict is happening when I have using the @TestConfiguration and the @Import annotation - thanks in advance 🙏

[kqr]

does not @SpringBootApplication componentScan, so that in your test you have your normal and mock beans?

[thanksforallthefish]

yes, you also get the same message from the exception No qualifying bean of type 'com.example.demo.NormalComponent' available: expected single matching bean but found 2: normalComponent,normalComponentMock

[thanksforallthefish]

`TestConfiguration`s are not picked by component scan (I think)

[thanksforallthefish]

one workaround could be to use `@Primary`on `normalComponentMock`(again, I think, I would just have gone with mockbean), or if you need the same mockbean in multiple test you can use `@ConditionalOnXYZ`and disable class NormalComponent .eg

@Component
@ConditionalOnProperty(...)
class NormalComponent()

[dr.dreigh]

does not @SpringBootApplication componentScan, so that in your test you have your normal and mock beans?

Yeah I think that is happening.

If I put @Primary in the non-test Bean we don't get the test Mockbean injected into the test

[dr.dreigh]

yeah, with @Primary...
expected: <I AM A MOCK!> but was: <Hi>

[dr.dreigh]

So I guess that's the crux of my problem, I want the test bean injecting into the test

[Jukka Siivonen]

You should put @Primary to your mock bean, and also set

spring:
  main:
    allow-bean-definition-overriding: true

[Jukka Siivonen]

this way your mock overrides the actual bean

[thanksforallthefish]

yep, @Primary goes on your test bean

[dr.dreigh]

gotcha!

[dr.dreigh]

tests pass!

[dr.dreigh]

so in this article (which may be a bit old)
how did they get it work without using primary:
https://mkyong.com/spring-boot/spring-boot-how-to-init-a-bean-for-testing/

[Jukka Siivonen]

probably because they introduce RestTemplateBuilder as a bean which "overrides" the one that is used under the hood, and what is injected to tests is actually TestRestTemplate (which was created by RestTemplateBuilder)

[dr.dreigh]

I see

[dr.dreigh]

Cool, think this give me enough to be getting on with. ^ Thank you all for your help! :)

[thanksforallthefish]

they leveraged @Conditional . there is a RestTemplateAutoConfiguration that creates a default RestTemplateBuilder, but that default one is annotated with @ConditionalOnMissingBean. that means that if your application defines another RestTemplateBuilder the one in your application is preferred

[dr.dreigh]

oh I see, thanks I've not used the conditional anotations

[thanksforallthefish]

if I am not wrong, you cannot do the same in your case, as both beans are defined by your application. maybe you can if both have the same name