Added a JUnit 5 extension to setup postgres

persistence-modules/spring-data-jpa-3/src/test/java/com/baeldung/PostgresExtension.java

@@ -0,0 +1,32 @@
+package com.baeldung;
+
+import org.junit.jupiter.api.extension.AfterAllCallback;
+import org.junit.jupiter.api.extension.BeforeAllCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+/**
+ * A JUnit 5 extension responsible for setting up a Postgres instance before all
+ * tests and tearing it down after them.
+ */
+public class PostgresExtension implements BeforeAllCallback, AfterAllCallback {
+
+    private PostgreSQLContainer<?> postgres;
+
+    @Override
+    public void beforeAll(ExtensionContext context) {
+        postgres = new PostgreSQLContainer<>("postgres:11.1")
+                .withDatabaseName("baeldung")
+                .withUsername("test")
+                .withExposedPorts(5432)
+                .withPassword("test");
+        postgres.start();
+        System.setProperty("TEST_PG_PORT", postgres.getFirstMappedPort() + "");
+    }
+
+    @Override
+    public void afterAll(ExtensionContext context) {
+        postgres.stop();
+        System.clearProperty("TEST_PG_PORT");
+    }
+}

persistence-modules/spring-data-jpa-3/src/test/resources/application-test.properties

@@ -1,4 +1,4 @@
 spring.jpa.hibernate.ddl-auto=update
-spring.datasource.url=jdbc:postgresql://localhost:54320/baeldung
+spring.datasource.url=jdbc:postgresql://localhost:${TEST_PG_PORT}/baeldung
 spring.datasource.username=test
 spring.datasource.password=test