Chapter 7. Mocking CDI beans

Quarkus allows you to mock certain CDI beans for specific tests.

You can mock an object using one of the following methods:

  • Override the bean you that you want to mock with a class in the src/test/java directory, and put the @Alternative and @Priority(1) annotations on the bean.
  • Use the io.quarkus.test.Mock stereotype annotation. The @Mock annotation contains the @Alternative, @Priority(1) and @Dependent annotations.

The following procedure shows how to mock an external service using the @Alternative annotation. Note, that this approach does not work with native image testing because the native image does not include the test alternatives.

Procedure

  1. Create the ExternalService in the src/main/java directory similar to the following example: 

    package org.acme.quickstart;

import javax.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class ExternalService {

    public String service() {
        return "external";
    }

}

  2. Create a class UsesExternalService that uses ExternalService in the src/main/java directory: 

    package org.acme.quickstart;

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;

@ApplicationScoped
public class UsesExternalService {

    @Inject
    ExternalService externalService;

    public String doSomething() {
        return externalService.service();
    }
}

  3. Create a test in the src/test/java directory similar to the following example: 

    package org.acme.quickstart;

import javax.inject.Inject;

import io.quarkus.test.junit.QuarkusTest;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

@QuarkusTest
class UsesExternalServiceTest {

    @Inject
    UsesExternalService usesExternalService;

    @Test
    public void testDoSomething() {
        Assertions.assertEquals("external", usesExternalService.doSomething());
    }
}

  4. Create the MockExternalService in the src/test/java that uses the @Alternative annotation: 

    package org.acme.quickstart;

import javax.annotation.Priority;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.inject.Alternative;

@Alternative
@Priority(1)
@ApplicationScoped
public class MockExternalService extends ExternalService { 1

    @Override
    public String service() {
        return "mock";
    }
}
    1
    The MockExternalService is injected wherever the ExternalService is being used. In this example, MockExternalService will be used in UsesExternalService.
    Note

    You can use the @Mock annotation instead of the @Alternative,@Priority(1) and @Dependent annotations.

    The following example shows how to create MockExternalService class that uses the @Mock annotation: 

    import javax.enterprise.context.ApplicationScoped;

import io.quarkus.test.Mock;

@Mock
@ApplicationScoped
public class MockExternalService extends ExternalService {

    @Override
    public String service() {
        return "mock";
    }
}

  5. Change the asserted string from "external" to "mock" in the test: 

    package org.acme.quickstart;

import javax.inject.Inject;

import io.quarkus.test.junit.QuarkusTest;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

@QuarkusTest
class UsesExternalServiceTest {

    @Inject
    UsesExternalService usesExternalService;

    @Test
    public void testDoSomething() {
        Assertions.assertEquals("mock", usesExternalService.doSomething());
    }
}