#29 - Use Testcontainers to run Postgres integration tests.

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.

We prefer a database based on TestContainers. Only if this can't be obtained do we try to access a local database for Postgres.

This minimizes the risk of accessing a database during tests that is not intended for that purpose.

If the system property `spring.data.r2dbc.test.preferLocalDatabase` is set to "true" the local database is preferred.

Original pull request: #51.

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

@@ -24,6 +24,8 @@ import java.util.concurrent.TimeUnit;
 
 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 @@ import org.junit.rules.ExternalResource;
  */
 public abstract class ExternalDatabase extends ExternalResource {
 
+	private static Logger LOG = LoggerFactory.getLogger(ExternalDatabase.class);
+
 	/**
 	 * @return the post of the database service.
 	 */
@@ -53,18 +57,37 @@ public abstract class ExternalDatabase extends ExternalResource {
 	 */
 	public abstract String getUsername();
 
+	/**
+	 * Throws an {@link AssumptionViolatedException} if the database cannot be reached.
+	 */
 	@Override
 	protected void before() {
 
-		try (Socket socket = new Socket()) {
-			socket.connect(new InetSocketAddress(getHostname(), getPort()), Math.toIntExact(TimeUnit.SECONDS.toMillis(5)));
-
-		} catch (IOException e) {
+		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) {
+			LOG.debug("external database not available.", e);
+		}
+
+		return false;
+	}
+
 	/**
 	 * @return password for the database user.
 	 */
@@ -122,4 +145,42 @@ public abstract class ExternalDatabase extends ExternalResource {
 			return password;
 		}
 	}
+
+	/**
+	 * An {@link ExternalDatabase} that couldn't get constructed.
+	 *
+	 * @author Jens Schauder
+	 */
+	static class NoSuchDatabase extends ExternalDatabase {
+
+		@Override
+		boolean checkValidity() {
+			return false;
+		}
+
+		@Override
+		public int getPort() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public String getHostname() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public String getDatabase() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public String getUsername() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public String getPassword() {
+			throw new UnsupportedOperationException();
+		}
+	}
 }

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

@@ -4,18 +4,24 @@ import io.r2dbc.postgresql.PostgresqlConnectionConfiguration;
 import io.r2dbc.postgresql.PostgresqlConnectionFactory;
 import io.r2dbc.spi.ConnectionFactory;
 
+import java.util.function.Supplier;
+
 import javax.sql.DataSource;
 
 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 ExternalDatabase testContainerDatabase;
+
 	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 +37,91 @@ 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();
+
+		if (Boolean.getBoolean("spring.data.r2dbc.test.preferLocalDatabase")) {
+
+			return getFirstWorkingDatabase( //
+					PostgresTestSupport::local, //
+					PostgresTestSupport::testContainer //
+			);
+		} else {
+
+			return getFirstWorkingDatabase( //
+					PostgresTestSupport::testContainer, //
+					PostgresTestSupport::local //
+			);
+		}
+	}
+
+	private static ExternalDatabase getFirstWorkingDatabase(Supplier<ExternalDatabase> first,
+			Supplier<ExternalDatabase> second) {
+
+		ExternalDatabase database = first.get();
+		if (database.checkValidity()) {
+			return database;
+		} else {
+			return second.get();
+		}
 	}
 
 	/**
 	 * 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() {
+
+		if (testContainerDatabase == null) {
+
+			try {
+				PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer();
+				postgreSQLContainer.start();
+
+				testContainerDatabase = ProvidedDatabase.builder() //
+						.hostname("localhost") //
+						.port(postgreSQLContainer.getFirstMappedPort()) //
+						.database(postgreSQLContainer.getDatabaseName()) //
+						.username(postgreSQLContainer.getUsername()) //
+						.password(postgreSQLContainer.getPassword()).build();
+
+			} catch (IllegalStateException ise) {
+				// docker is not available.
+				testContainerDatabase = new ExternalDatabase.NoSuchDatabase();
+			}
+
+		}
+
+		return testContainerDatabase;
+	}
+
 	/**
 	 * 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());
 	}
 
 	/**
@@ -72,4 +139,5 @@ public class PostgresTestSupport {
 
 		return dataSource;
 	}
+
 }

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

@@ -33,31 +33,35 @@ public class SqlServerTestSupport {
 
 	/**
 	 * Returns a locally provided database at {@code sqlserver:@localhost:1433/master}.
-	 *
-	 * @return
 	 */
 	public static ExternalDatabase database() {
 		return local();
 	}
 
 	/**
-	 * Returns a locally provided database at {@code postgres:@localhost:5432/postgres}.
-	 *
-	 * @return
+	 * Returns a locally provided database at {@code sqlserver:@localhost:1433/master}.
 	 */
 	private static ExternalDatabase local() {
-		return ProvidedDatabase.builder().hostname("localhost").port(1433).database("master").username("sa")
-				.password("A_Str0ng_Required_Password").build();
+
+		return ProvidedDatabase.builder() //
+				.hostname("localhost") //
+				.port(1433) //
+				.database("master") //
+				.username("sa") //
+				.password("A_Str0ng_Required_Password") //
+				.build();
 	}
 
 	/**
 	 * Creates a new {@link ConnectionFactory} configured from the {@link ExternalDatabase}..
 	 */
 	public static ConnectionFactory createConnectionFactory(ExternalDatabase database) {
+
 		return new MssqlConnectionFactory(MssqlConnectionConfiguration.builder().host(database.getHostname()) //
 				.database(database.getDatabase()) //
 				.username(database.getUsername()) //
 				.password(database.getPassword()) //
+				.port(database.getPort()) //
 				.build());
 	}