Chapter 6. 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.

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());
    }
}