I have 2 microservices:

Service A has an endpoint to create Article entities. This entity has a property Supplier among others. When creating an Article, the corresponding method calls (using Feign) an endpoint from Service B which returns the Supplier if it exists.

@Getter
@Setter
@NoArgsConstructor
@Entity
@EqualsAndHashCode
@Table(name = "article")
public class ArticleDAO {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @Column(name = "name")
    private String name;

    ...

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "supplier_id", referencedColumnName = "id")
    private SupplierDAO supplier;
}

Code to create an Article:

@Override
    public Article createArticle(final Article article, final String usuario) {
        final List<ArticleDAO> articleDAOS;
        
        if(this.suppliersFeignClient.getSupplier(article.getSupplier().getId().getBody() == null)
                // do something
        this.checkArticleDontExistByName(article);
        articles.forEach(article -> article.setUser(usuario));
        articleDAOS = this.modelMapper.map(articles, new TypeToken<List<ArticleDAO>>(){}.getType());
        this.articleRepository.saveAll(articleDAOS);
        return this.modelMapper.map(articleDAOS, new TypeToken<List<Article>>(){}.getType());
    }

Here, I am not finding a way to connect Service A with Service B whith both running a database for integration tests since both use mysql. I would need Service A to run a mysql container using TestContainers and also to run Service B which also needs its own mysql container.

I am learning about Integration Tests with microservices and on my journey I found the TestContainers library which I managed to write tests using a mysql image but without having interaction with other microservices. Now that I have 2 microservices I have no idea at all about how to write the tests for this since Service B also uses mysql.

Can anyone give me any guidance on how to achieve this? Is TestContainers not good for integration tests when there’s more than one service?

I know this question could be a bit tangly, I will add more info or code if needed but so far I just have this in my integration test which works perfectly if I comment this.suppliersFeignClient.getSupplier(article.getSupplier().getId().getBody() == null:

    @ServiceConnection
    @Container
    private static final MySQLContainer<?> mySQLContainer = new MySQLContainer<>(ContainersConstants.MYSQL_CONTAINER_TAG);
    @Autowired
    private TestRestTemplate restTemplate;
    @Autowired
    private ArticlesService articlesService;
    @Autowired
    private ModelMapper modelMapper;
    @Autowired
    private ArticleRepository articleRepository;

    @BeforeAll
    static void beforeAll() {
        mySQLContainer.start();
    }



    @AfterAll
        static void afterAll() {
            mySQLContainer.stop();
        }

    @Test
    @DisplayName("Create articles /articles")
    void WHEN_calling_create_articles_THEN_status_is_200() {
        final List<ArticleDTO> articleDTOS = Instancio.ofList(ArticleDTO.class).size(3)
                .ignore(field(ArticleDTO::getId))
                .ignore(field(ArticleDTO::getCategory))
                .ignore(field(ArticleDTO::getSupplier))
                .create();
        final CreateArticlesRequest createArticlesRequest = CreateArticlesRequest.builder()
                .articles(articleDTOS)
                .user(Instancio.create(String.class))
                .build();
        final ResponseEntity<CreateArticlesResponse> response = restTemplate.exchange(restTemplate.getRootUri() + URIConstants.ARTICLES_URI,
                HttpMethod.POST, new HttpEntity<>(createArticlesRequest), new ParameterizedTypeReference<>() {});
        final List<ArticleDTO> articles = Objects.requireNonNull(response.getBody()).getArticles();

        articles.forEach(article -> article.setId(null));

        assertEquals(articles.size(), articleDTOS.size() , "articles.size() should be " + articleDTOS.size());
        assertTrue(articles.containsAll(articleDTOS), "articles should contain the same elements as articulosDTOS");
        assertEquals(HttpStatus.OK, response.getStatusCode(), "Status Code should be " + HttpStatus.OK);
    }

Thanks