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 config

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();
    }
}