#29 - Start a Postgres database in Docker if no local database can be found.

Postgres integration tests now run either with a locally installed and started database or if no such database can be found an instance gets started in a Docker container via Testcontainers.

Author: schauder

src/test/java/org/springframework/data/r2dbc/testing/ExternalDatabase.java

@@ -24,6 +24,8 @@
 
 import org.junit.AssumptionViolatedException;
 import org.junit.rules.ExternalResource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * {@link ExternalResource} wrapper to encapsulate {@link ProvidedDatabase} and
@@ -33,6 +35,8 @@
  */
 public abstract class ExternalDatabase extends ExternalResource {
 
+	private static Logger LOG = LoggerFactory.getLogger(ExternalDatabase.class);
+
 	/**
 	 * @return the post of the database service.
 	 */
@@ -53,16 +57,35 @@ public abstract class ExternalDatabase extends ExternalResource {
 	 */
 	public abstract String getUsername();
 
+	/**
+	 * Throws an {@link AssumptionViolatedException} if the database cannot be reached.
+	 */
 	@Override
 	protected void before() {
 
+		if (!checkValidity()) {
+			throw new AssumptionViolatedException(
+					String.format("Cannot connect to %s:%d. Skipping tests.", getHostname(), getPort()));
+		}
+	}
+
+	/**
+	 * performs a test if the database can actually be reached.
+	 *
+	 * @return true, if the database could be reached.
+	 */
+	boolean checkValidity() {
+
 		try (Socket socket = new Socket()) {
+
 			socket.connect(new InetSocketAddress(getHostname(), getPort()), Math.toIntExact(TimeUnit.SECONDS.toMillis(5)));
+			return  true;
 
 		} catch (IOException e) {
-			throw new AssumptionViolatedException(
-					String.format("Cannot connect to %s:%d. Skipping tests.", getHostname(), getPort()));
+			LOG.debug("external database not available.", e);
 		}
+
+		return false;
 	}
 
 	/**

src/test/java/org/springframework/data/r2dbc/testing/PostgresTestSupport.java

@@ -8,14 +8,18 @@
 
 import org.postgresql.ds.PGSimpleDataSource;
 import org.springframework.data.r2dbc.testing.ExternalDatabase.ProvidedDatabase;
+import org.testcontainers.containers.PostgreSQLContainer;
 
 /**
  * Utility class for testing against Postgres.
  *
  * @author Mark Paluch
+ * @author Jens Schauder
  */
 public class PostgresTestSupport {
 
+	private static final PostgreSQLContainer POSTGRESQL_CONTAINER = new PostgreSQLContainer();
+
 	public static String CREATE_TABLE_LEGOSET = "CREATE TABLE legoset (\n" //
 			+ "    id          integer CONSTRAINT id PRIMARY KEY,\n" //
 			+ "    name        varchar(255) NOT NULL,\n" //
@@ -31,30 +35,60 @@ public class PostgresTestSupport {
 	public static String INSERT_INTO_LEGOSET = "INSERT INTO legoset (id, name, manual) VALUES($1, $2, $3)";
 
 	/**
-	 * Returns a locally provided database at {@code postgres:@localhost:5432/postgres}.
+	 * Returns a database either hosted locally at {@code postgres:@localhost:5432/postgres} or running inside Docker.
 	 *
-	 * @return
+	 * @return information about the database. Guaranteed to be not {@literal null}.
 	 */
 	public static ExternalDatabase database() {
-		return local();
+
+		ExternalDatabase local = local();
+		if (local.checkValidity()) {
+			return local;
+		} else {
+			return testContainer();
+		}
 	}
 
 	/**
 	 * Returns a locally provided database at {@code postgres:@localhost:5432/postgres}.
-	 *
-	 * @return
 	 */
 	private static ExternalDatabase local() {
-		return ProvidedDatabase.builder().hostname("localhost").port(5432).database("postgres").username("postgres")
+
+		return ProvidedDatabase.builder() //
+				.hostname("localhost") //
+				.port(5432) //
+				.database("postgres") //
+				.username("postgres") //
 				.password("").build();
 	}
 
+	/**
+	 * Returns a database provided via Testcontainers.
+	 */
+	private static ExternalDatabase testContainer() {
+
+		POSTGRESQL_CONTAINER.start();
+
+		return ProvidedDatabase.builder() //
+				.hostname("localhost") //
+				.port(POSTGRESQL_CONTAINER.getFirstMappedPort()) //
+				.database(POSTGRESQL_CONTAINER.getDatabaseName()) //
+				.username(POSTGRESQL_CONTAINER.getUsername()) //
+				.password(POSTGRESQL_CONTAINER.getPassword()).build();
+	}
+
 	/**
 	 * Creates a new {@link ConnectionFactory} configured from the {@link ExternalDatabase}..
 	 */
 	public static ConnectionFactory createConnectionFactory(ExternalDatabase database) {
-		return new PostgresqlConnectionFactory(PostgresqlConnectionConfiguration.builder().host(database.getHostname())
-				.database(database.getDatabase()).username(database.getUsername()).password(database.getPassword()).build());
+
+		return new PostgresqlConnectionFactory(PostgresqlConnectionConfiguration.builder() //
+				.host(database.getHostname()) //
+				.database(database.getDatabase()) //
+				.port(database.getPort()) //
+				.username(database.getUsername()) //
+				.password(database.getPassword()) //
+				.build());
 	}
 
 	/**