Spring

Kotest offers a Spring extension that allows you to test code that uses the Spring framework for dependency injection.

tip

If you prefer to see an example rather than read docs, then there is a sample project using spring webflux here

In order to use this extension, you need to add io.kotest.extensions:kotest-extensions-spring module to your test compile path. The latest version can always be found on maven central here.

Note: The maven group id differs from the core test framework (io.kotest.extensions).

The Spring extension requires you to activate it for all test classes, or per test class. To activate it globally, register the SpringExtension in project config:

class ProjectConfig : AbstractProjectConfig() {
   override fun extensions() = listOf(SpringExtension)
}

To activate it per test class:

class MyTestSpec : FunSpec() {
   override fun extensions() = listOf(SpringExtension)
}

In order to let Spring know which configuration class to use, you must annotate your Spec classes with @ContextConfiguration. This should point to a class annotated with the Spring @Configuration annotation. Alternatively, you can use @ActiveProfiles to point to a specific application context file.

note

In Kotest 4.3 and earlier, the Spring extension was called SpringListener. This extension has now been deprecated in favour of SpringExtension. The usage is the same, but the SpringExtension has more functionality.

Constructor Injection

For constructor injection, Kotest automatically registers a SpringAutowireConstructorExtension when the spring module is added to the build, assuming auto scan is enabled (see Project Config). If Auto scan is disabled, you will need to manually load the extension in your Project config.

This extension will intercept each call to create a Spec instance and will autowire the beans declared in the primary constructor.

The following example is a test class which requires a service called UserService in its primary constructor. This service class is just a regular spring bean which has been annotated with @Component.

@ContextConfiguration(classes = [(Components::class)])
class SpringAutowiredConstructorTest(service: UserService) : WordSpec() {
  init {
    "SpringExtension" should {
      "have autowired the service" {
        service.repository.findUser().name shouldBe "system_user"
      }
    }
  }
}

TestContexts

The Spring extensions makes available the TestContextManager via the coroutine context that tests execute in. You can gain a handle to this instance through the testContextManager() extension method.

From this you can get the testContext that Spring is using.

class MySpec(service: UserService) : WordSpec() {
  init {
    "SpringExtension" should {
      "provide the test context manager" {
         println("The context is " + testContextManager().testContext)
      }
    }
  }
}

Test Method Callbacks

Spring has various test callbacks such as beforeTestMethod that are based around the idea that tests are methods. This assumption is fine for legacy test frameworks like JUnit but not applicable to modern test frameworks like Kotest where tests are functions.

Therefore, when using a spec style that is nested, you can customize when the test method callbacks are fired. By default, this is on the leaf node. You can set these to fire on the root nodes by passing a SpringTestLifecycleMode argument to the extension:

class ProjectConfig : AbstractProjectConfig() {
   override fun extensions() = listOf(SpringTestExtension(SpringTestLifecycleMode.Root))
}

Final Classes

When using a final class, you may receive a warning from Kotest:

Using SpringListener on a final class. If any Spring annotation fails to work, try making this class open

If you wish, you can disable this warning by setting the system property kotest.listener.spring.ignore.warning to true.