How can I mock db connection in Spring Boot for testing purpose?

Question

Situation:

1. I am using Spring Cloud with Spring Boot in a microservice, that microservice is loading a DB config information to configure a connection.
2. I created a test to get the rest interfaces using Swagger for documentation.
3. I want to disable the loading of DB configuration because is not necessary.

Here is the code:

@WebAppConfiguration
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {Application.class, Swagger2MarkupTest.class}, loader = SpringApplicationContextLoader.class)
@ActiveProfiles("test")

public class Swagger2MarkupTest {

    @Autowired
    private WebApplicationContext context;

    private MockMvc mockMvc;

    @Autowired
    protected Environment env;

    @Before
    public void setUp() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context).build();
    }

    @Test
    public void convertSwaggerToAsciiDoc() throws Exception {
        this.mockMvc.perform(get("/v2/api-docs").accept(MediaType.APPLICATION_JSON))
                .andDo(Swagger2MarkupResultHandler.outputDirectory("target/docs/asciidoc/generated")
                        .withExamples("target/docs/asciidoc/generated/exampless").build())
                .andExpect(status().isOk());
    }
}

How can I run the test without loading the database configuration? Is this possible?

Answer 1

There is an option to fake Spring bean with just plain Spring features. You need to use @Primary, @Profile and @ActiveProfiles annotations for it.

I wrote a blog post on the topic.

You can use in memory DB (e.g. H2) to replace real data source. Something like this:

@Configuration
public class TestingDataSourceConfig {

    @Bean
    @Primary
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .generateUniqueName(true)
            .setType(H2)
            .setScriptEncoding("UTF-8")
            .ignoreFailedDrops(true)
            .addScript("schema.sql")
            .addScripts("user_data.sql", "country_data.sql")
            .build();
    }
}