feat: Use Testcontainers for controller tests (#38)

[Testcontainers](https://github.com/testcontainers) allow us to spin up a temporary Docker image during tests. For this project, we will spin up a temporary PostgreSQL database to run the controller tests against a real PostgreSQL database instead of an in-memory H2 database. There are differences between PostgreSQL and H2 databases so if you plan to use a PostgreSQL database in production, it also makes sense to mimic this by using a PostgreSQL database in the tests. H2 databases are useful for quickly testing and running the system locally, but it is better to use Testcontainers to run a real PostgreSQL database for the controller tests.

Use Testcontainers for controller tests:
- Add `Testcontainers` annotation in controller tests.
- Define a `PostgreSQLContainer` which will be used for the tests.
- Add `application-postgres.yml` with connection settings for PostgreSQL.
- Add `ActiveProfiles("postgres")` annotation in controller test which ensures it uses `application-postgres.yml`.
- Update `README.md`.

Author: thorlauridsen

README.md

@@ -151,6 +151,17 @@ and http://localhost:8081/ to view the Swagger documentation for each service.
 - [Liquibase](https://github.com/liquibase/liquibase) - Used to manage database schema changelogs
 - [WireMock](https://github.com/wiremock/wiremock) - For mocking HTTP services in tests
 - [Lombok](https://github.com/projectlombok/lombok) - Used to reduce boilerplate code
+- [Testcontainers](https://github.com/testcontainers) - Creates a temporary PostgreSQL database for tests
+
+## Testing
+You can run the tests for this project using the following command:
+```
+./gradlew test
+```
+Please note that this project uses
+[Testcontainers](https://github.com/testcontainers)
+to create a temporary PostgreSQL database for tests. This requires
+a local Docker instance to be running when executing the tests.
 
 ## Gradle best practices for Kotlin
 [docs.gradle.org](https://docs.gradle.org/current/userguide/performance.html) - [kotlinlang.org](https://kotlinlang.org/docs/gradle-best-practices.html)

apps/provider/src/main/resources/application-postgres.yml

@@ -0,0 +1,7 @@
+spring:
+  datasource:
+    url: jdbc:postgresql://localhost:5432/sample-db
+    username: postgres
+    password: postgres
+  liquibase:
+    enabled: true

apps/provider/src/test/java/com/github/thorlauridsen/FlightControllerTest.java

@@ -11,20 +11,35 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.MediaType;
+import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.web.servlet.client.RestTestClient;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
 import tools.jackson.databind.json.JsonMapper;
 
 import static com.github.thorlauridsen.controller.BaseEndpoint.FLIGHT_BASE_ENDPOINT;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+/**
+ * Test class for testing the FlightController.
+ * A local Docker instance is required to run the tests as Testcontainers is used.
+ */
+@ActiveProfiles("postgres")
 @AutoConfigureRestTestClient
 @SpringBootTest
+@Testcontainers
 @TestMethodOrder(MethodOrderer.OrderAnnotation.class)
 class FlightControllerTest {
 
+    @Container
+    @ServiceConnection
+    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
+
     @Autowired
     private RestTestClient restTestClient;
 

apps/provider/src/test/java/com/github/thorlauridsen/HotelControllerTest.java

@@ -11,20 +11,35 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.MediaType;
+import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.web.servlet.client.RestTestClient;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
 import tools.jackson.databind.json.JsonMapper;
 
 import static com.github.thorlauridsen.controller.BaseEndpoint.HOTEL_BASE_ENDPOINT;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+/**
+ * Test class for testing the HotelController.
+ * A local Docker instance is required to run the tests as Testcontainers is used.
+ */
+@ActiveProfiles("postgres")
 @AutoConfigureRestTestClient
 @SpringBootTest
+@Testcontainers
 @TestMethodOrder(MethodOrderer.OrderAnnotation.class)
 class HotelControllerTest {
 
+    @Container
+    @ServiceConnection
+    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
+
     @Autowired
     private RestTestClient restTestClient;
 

apps/provider/src/test/java/com/github/thorlauridsen/RentalCarControllerTest.java

@@ -11,20 +11,35 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureRestTestClient;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.MediaType;
+import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.web.servlet.client.RestTestClient;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
 import tools.jackson.databind.json.JsonMapper;
 
 import static com.github.thorlauridsen.controller.BaseEndpoint.RENTAL_CAR_BASE_ENDPOINT;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
+/**
+ * Test class for testing the RentalCarController.
+ * A local Docker instance is required to run the tests as Testcontainers is used.
+ */
+@ActiveProfiles("postgres")
 @AutoConfigureRestTestClient
 @SpringBootTest
+@Testcontainers
 @TestMethodOrder(MethodOrderer.OrderAnnotation.class)
 class RentalCarControllerTest {
 
+    @Container
+    @ServiceConnection
+    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
+
     @Autowired
     private RestTestClient restTestClient;