Add support for Oracle's R2DBC driver.

We support Oracle's experimental R2DBC driver by providing a dialect including bind markers. Since the driver is not yet available from Maven Central and it requires module-path support for ServiceLoader discovery, we need to apply a few workarounds including absence check for our integration tests.

See #230

pom.xml

@@ -216,6 +216,13 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+			<groupId>com.oracle.database.jdbc</groupId>
+			<artifactId>ojdbc11</artifactId>
+			<version>21.1.0.0</version>
+			<scope>test</scope>
+		</dependency>
+
 		<!-- R2DBC Drivers -->
 
 		<dependency>
@@ -288,6 +295,12 @@
 			</exclusions>
 		</dependency>
 
+		<dependency>
+			<groupId>org.testcontainers</groupId>
+			<artifactId>oracle-xe</artifactId>
+			<scope>test</scope>
+		</dependency>
+
 		<dependency>
 			<groupId>org.testcontainers</groupId>
 			<artifactId>postgresql</artifactId>
@@ -448,6 +461,22 @@
 				</plugins>
 			</build>
 		</profile>
+
+		<profile>
+			<id>java11</id>
+
+			<!-- enable once oracle-r2db is available from Maven Central
+			<dependencies>
+				<dependency>
+					<groupId>com.oracle.database.r2dbc</groupId>
+					<artifactId>oracle-r2dbc</artifactId>
+					<version>0.1.0</version>
+					<scope>test</scope>
+				</dependency>
+			</dependencies>
+
+			-->
+		</profile>
 	</profiles>
 
 	<repositories>

src/main/asciidoc/new-features.adoc

@@ -9,10 +9,12 @@
 [[new-features.1-2-0]]
 == What's New in Spring Data R2DBC 1.2.0
 
-* Deprecate Spring Data R2DBC `DatabaseClient` and move off deprecated API in favor of Spring R2DBC. Consult the <<upgrading.1.1-1.2,Migration Guide>> for further details.
+* Deprecate Spring Data R2DBC `DatabaseClient` and move off deprecated API in favor of Spring R2DBC.
+Consult the <<upgrading.1.1-1.2,Migration Guide>> for further details.
 * Support for <<entity-callbacks>>.
 * <<r2dbc.auditing,Auditing>> through `@EnableR2dbcAuditing`.
 * Support for `@Value` in persistence constructors.
+* Support for Oracle's R2DBC driver.
 
 [[new-features.1-1-0]]
 == What's New in Spring Data R2DBC 1.1.0

src/main/asciidoc/reference/r2dbc-core.adoc

@@ -150,7 +150,7 @@ There is a https://github.com/spring-projects/spring-data-examples[GitHub reposi
 [[r2dbc.connecting]]
 == Connecting to a Relational Database with Spring
 
-One of the first tasks when using relational databases and Spring is to create a `io.r2dbc.spi.ConnectionFactory` object by using the IoC container. Make sure to use a <<r2dbc.drivers,supported database and driver>>.
+One of the first tasks when using relational databases and Spring is to create a `io.r2dbc.spi.ConnectionFactory` object by using the IoC container.Make sure to use a <<r2dbc.drivers,supported database and driver>>.
 
 [[r2dbc.connectionfactory]]
 === Registering a `ConnectionFactory` Instance using Java-based Metadata
@@ -173,7 +173,7 @@ public class ApplicationConfiguration extends AbstractR2dbcConfiguration {
 ----
 ====
 
-This approach lets you use the standard `io.r2dbc.spi.ConnectionFactory` instance, with the container using Spring's `AbstractR2dbcConfiguration`. As compared to registering a `ConnectionFactory` instance directly, the configuration support has the added advantage of also providing the container with an `ExceptionTranslator` implementation that translates R2DBC exceptions to exceptions in Spring's portable `DataAccessException` hierarchy for data access classes annotated with the `@Repository` annotation. This hierarchy and the use of `@Repository` is described in {spring-framework-ref}/data-access.html[Spring's DAO support features].
+This approach lets you use the standard `io.r2dbc.spi.ConnectionFactory` instance, with the container using Spring's `AbstractR2dbcConfiguration`.As compared to registering a `ConnectionFactory` instance directly, the configuration support has the added advantage of also providing the container with an `ExceptionTranslator` implementation that translates R2DBC exceptions to exceptions in Spring's portable `DataAccessException` hierarchy for data access classes annotated with the `@Repository` annotation.This hierarchy and the use of `@Repository` is described in {spring-framework-ref}/data-access.html[Spring's DAO support features].
 
 `AbstractR2dbcConfiguration` also registers `DatabaseClient`, which is required for database interaction and for Repository implementation.
 
@@ -191,11 +191,11 @@ Spring Data R2DBC ships with dialect impelemtations for the following drivers:
 * https://github.com/mirromutth/r2dbc-mysql[MySQL] (`dev.miku:r2dbc-mysql`)
 * https://github.com/jasync-sql/jasync-sql[jasync-sql MySQL] (`com.github.jasync-sql:jasync-r2dbc-mysql`)
 * https://github.com/r2dbc/r2dbc-postgresql[Postgres] (`io.r2dbc:r2dbc-postgresql`)
+* https://github.com/oracle/oracle-r2dbc[Oracle] (`com.oracle.database.r2dbc:oracle-r2dbc`)
 
 Spring Data R2DBC reacts to database specifics by inspecting the `ConnectionFactory` and selects the appropriate database dialect accordingly.
 You need to configure your own {spring-data-r2dbc-javadoc}/api/org/springframework/data/r2dbc/dialect/R2dbcDialect.html[`R2dbcDialect`] if the driver you use is not yet known to Spring Data R2DBC.
 
 TIP: Dialects are resolved by {spring-data-r2dbc-javadoc}/org/springframework/data/r2dbc/dialect/DialectResolver.html[`DialectResolver`] from a `ConnectionFactory`, typically by inspecting `ConnectionFactoryMetadata`.
- +
-You can let Spring auto-discover your `R2dbcDialect` by registering a class that implements `org.springframework.data.r2dbc.dialect.DialectResolver$R2dbcDialectProvider` through `META-INF/spring.factories`.
++ You can let Spring auto-discover your `R2dbcDialect` by registering a class that implements `org.springframework.data.r2dbc.dialect.DialectResolver$R2dbcDialectProvider` through `META-INF/spring.factories`.
 `DialectResolver` discovers dialect provider implementations from the class path using Spring's `SpringFactoriesLoader`.

src/main/java/org/springframework/data/r2dbc/dialect/DialectResolver.java

@@ -115,6 +115,7 @@ public class DialectResolver {
 			BUILTIN.put("Microsoft SQL Server", SqlServerDialect.INSTANCE);
 			BUILTIN.put("MySQL", MySqlDialect.INSTANCE);
 			BUILTIN.put("MariaDB", MySqlDialect.INSTANCE);
+			BUILTIN.put("Oracle", OracleDialect.INSTANCE);
 			BUILTIN.put("PostgreSQL", PostgresDialect.INSTANCE);
 		}
 

src/main/java/org/springframework/data/r2dbc/dialect/OracleDialect.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.dialect;
+
+import org.springframework.r2dbc.core.binding.BindMarkersFactory;
+
+/**
+ * An SQL dialect for Oracle.
+ *
+ * @author Mark Paluch
+ * @since 1.2.6
+ */
+public class OracleDialect extends org.springframework.data.relational.core.dialect.OracleDialect
+		implements R2dbcDialect {
+
+	/**
+	 * Singleton instance.
+	 */
+	public static final OracleDialect INSTANCE = new OracleDialect();
+
+	private static final BindMarkersFactory NAMED = BindMarkersFactory.named(":", "P", 32,
+			OracleDialect::filterBindMarker);
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.r2dbc.dialect.Dialect#getBindMarkersFactory()
+	 */
+	@Override
+	public BindMarkersFactory getBindMarkersFactory() {
+		return NAMED;
+	}
+
+	private static String filterBindMarker(CharSequence input) {
+
+		StringBuilder builder = new StringBuilder();
+
+		for (int i = 0; i < input.length(); i++) {
+
+			char ch = input.charAt(i);
+
+			// ascii letter or digit
+			if (Character.isLetterOrDigit(ch) && ch < 127) {
+				builder.append(ch);
+			}
+		}
+
+		if (builder.length() == 0) {
+			return "";
+		}
+
+		return "_" + builder;
+	}
+
+}

src/test/java/org/springframework/data/r2dbc/core/OracleDatabaseClientIntegrationTests.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.core;
+
+import io.r2dbc.spi.ConnectionFactory;
+
+import javax.sql.DataSource;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import org.springframework.data.r2dbc.testing.EnabledOnClass;
+import org.springframework.data.r2dbc.testing.ExternalDatabase;
+import org.springframework.data.r2dbc.testing.OracleTestSupport;
+
+/**
+ * Integration tests for {@link DatabaseClient} against Oracle.
+ *
+ * @author Mark Paluch
+ */
+@EnabledOnClass("oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl")
+public class OracleDatabaseClientIntegrationTests extends AbstractDatabaseClientIntegrationTests {
+
+	@RegisterExtension public static final ExternalDatabase database = OracleTestSupport.database();
+
+	@Override
+	protected DataSource createDataSource() {
+		return OracleTestSupport.createDataSource(database);
+	}
+
+	@Override
+	protected ConnectionFactory createConnectionFactory() {
+		return OracleTestSupport.createConnectionFactory(database);
+	}
+
+	@Override
+	protected String getCreateTableStatement() {
+		return OracleTestSupport.CREATE_TABLE_LEGOSET;
+	}
+
+	@Override
+	@Disabled("https://github.com/oracle/oracle-r2dbc/issues/9")
+	public void executeSelectNamedParameters() {}
+}

src/test/java/org/springframework/data/r2dbc/dialect/OracleDialectUnitTests.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.dialect;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.r2dbc.core.binding.BindMarker;
+import org.springframework.r2dbc.core.binding.BindMarkers;
+
+/**
+ * Unit tests for {@link OracleDialect}.
+ *
+ * @author Mark Paluch
+ */
+class OracleDialectUnitTests {
+
+	@Test // gh-230
+	void shouldUseNamedPlaceholders() {
+
+		BindMarkers bindMarkers = OracleDialect.INSTANCE.getBindMarkersFactory().create();
+
+		BindMarker first = bindMarkers.next();
+		BindMarker second = bindMarkers.next("'foo!bar");
+
+		assertThat(first.getPlaceholder()).isEqualTo(":P0");
+		assertThat(second.getPlaceholder()).isEqualTo(":P1_foobar");
+	}
+
+}

src/test/java/org/springframework/data/r2dbc/repository/OracleR2dbcRepositoryIntegrationTests.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2019-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.repository;
+
+import io.r2dbc.spi.ConnectionFactory;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import javax.sql.DataSource;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan.Filter;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.FilterType;
+import org.springframework.data.r2dbc.config.AbstractR2dbcConfiguration;
+import org.springframework.data.r2dbc.repository.config.EnableR2dbcRepositories;
+import org.springframework.data.r2dbc.repository.support.R2dbcRepositoryFactory;
+import org.springframework.data.r2dbc.testing.EnabledOnClass;
+import org.springframework.data.r2dbc.testing.ExternalDatabase;
+import org.springframework.data.r2dbc.testing.OracleTestSupport;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+/**
+ * Integration tests for {@link LegoSetRepository} using {@link R2dbcRepositoryFactory} against Oracle.
+ *
+ * @author Mark Paluch
+ */
+@ExtendWith(SpringExtension.class)
+@ContextConfiguration
+@EnabledOnClass("oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl")
+public class OracleR2dbcRepositoryIntegrationTests extends AbstractR2dbcRepositoryIntegrationTests {
+
+	@RegisterExtension public static final ExternalDatabase database = OracleTestSupport.database();
+
+	@Configuration
+	@EnableR2dbcRepositories(considerNestedRepositories = true,
+			includeFilters = @Filter(classes = OracleLegoSetRepository.class, type = FilterType.ASSIGNABLE_TYPE))
+	static class IntegrationTestConfiguration extends AbstractR2dbcConfiguration {
+
+		@Bean
+		@Override
+		public ConnectionFactory connectionFactory() {
+			return OracleTestSupport.createConnectionFactory(database);
+		}
+	}
+
+	@Override
+	protected DataSource createDataSource() {
+		return OracleTestSupport.createDataSource(database);
+	}
+
+	@Override
+	protected ConnectionFactory createConnectionFactory() {
+		return OracleTestSupport.createConnectionFactory(database);
+	}
+
+	@Override
+	protected String getCreateTableStatement() {
+		return OracleTestSupport.CREATE_TABLE_LEGOSET_WITH_ID_GENERATION;
+	}
+
+	@Override
+	protected Class<? extends LegoSetRepository> getRepositoryInterfaceType() {
+		return OracleLegoSetRepository.class;
+	}
+
+	interface OracleLegoSetRepository extends LegoSetRepository {
+
+		@Override
+		@Query("SELECT name FROM legoset")
+		Flux<Named> findAsProjection();
+
+		@Override
+		@Query("SELECT * FROM legoset WHERE manual = :manual")
+		Mono<LegoSet> findByManual(int manual);
+
+		@Override
+		@Query("SELECT id FROM legoset")
+		Flux<Integer> findAllIds();
+	}
+}

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

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.testing;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+/**
+ * {@code @EnabledOnClass} is used to signal that the annotated test class or test method is only <em>enabled</em> if
+ * the specified {@link #value() class} is present.
+ * <p>
+ * When applied at the class level, all test methods within that class will be enabled on presence of the specified
+ * class.
+ * <p>
+ * If a test method is disabled via this annotation, that does not prevent the test class from being instantiated.
+ * Rather, it prevents the execution of the test method and method-level lifecycle callbacks such as {@code @BeforeEach}
+ * methods, {@code @AfterEach} methods, and corresponding extension APIs.
+ * <p>
+ * This annotation may be used as a meta-annotation in order to create a custom <em>composed annotation</em> that
+ * inherits the semantics of this annotation.
+ *
+ * @see JRE
+ * @see org.junit.jupiter.api.Disabled
+ */
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@ExtendWith(EnabledOnClassCondition.class)
+public @interface EnabledOnClass {
+
+	String value();
+}

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

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.testing;
+
+import static org.junit.jupiter.api.extension.ConditionEvaluationResult.*;
+import static org.junit.platform.commons.util.AnnotationUtils.*;
+
+import org.junit.jupiter.api.extension.ConditionEvaluationResult;
+import org.junit.jupiter.api.extension.ExecutionCondition;
+import org.junit.jupiter.api.extension.ExtensionContext;
+
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link ExecutionCondition} for {@link EnabledOnClass @EnabledOnClass}.
+ *
+ * @author Mark Paluch
+ * @see EnabledOnClass
+ */
+class EnabledOnClassCondition implements ExecutionCondition {
+
+	@Override
+	public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext context) {
+		return findAnnotation(context.getElement(), EnabledOnClass.class) //
+				.map(annotation -> isEnabled(annotation)
+						? enabled(String.format("Class '%s' found on the class path.", annotation.value()))
+						: disabled(String.format("Class '%s' not found on the class path.", annotation.value()))) //
+				.orElseGet(this::enabledByDefault);
+	}
+
+	private boolean isEnabled(EnabledOnClass annotation) {
+		return ClassUtils.isPresent(annotation.value(), EnabledOnClassCondition.class.getClassLoader());
+	}
+
+	private ConditionEvaluationResult enabledByDefault() {
+		return enabled("@EnabledOnClass is not present");
+	}
+
+}

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

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.testing;
+
+import io.r2dbc.spi.ConnectionFactory;
+import io.r2dbc.spi.ConnectionFactoryOptions;
+import io.r2dbc.spi.ConnectionFactoryProvider;
+
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * {@link ConnectionFactoryProvider} for Oracle's R2DBC driver. Allows for absence of the driver which is required when
+ * using Java 8 as the ServiceLoader requires presence of classes listed in the service loader manifest.
+ *
+ * @author Mark Paluch
+ */
+public class OracleConnectionFactoryProviderWrapper implements ConnectionFactoryProvider {
+
+	private final ConnectionFactoryProvider delegate;
+
+	public OracleConnectionFactoryProviderWrapper() {
+
+		if (ClassUtils.isPresent("oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl", getClass().getClassLoader())) {
+
+			delegate = createProvider();
+		} else {
+			delegate = null;
+		}
+
+	}
+
+	private static ConnectionFactoryProvider createProvider() {
+
+		try {
+			return (ConnectionFactoryProvider) Class.forName("oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl")
+					.newInstance();
+		} catch (ReflectiveOperationException e) {
+			ReflectionUtils.handleReflectionException(e);
+		}
+		return null;
+	}
+
+	@Override
+	public ConnectionFactory create(ConnectionFactoryOptions connectionFactoryOptions) {
+		if (delegate != null) {
+			return delegate.create(connectionFactoryOptions);
+		}
+		throw new IllegalStateException(
+				"Oracle R2DBC (oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl) is not on the class path");
+	}
+
+	@Override
+	public boolean supports(ConnectionFactoryOptions connectionFactoryOptions) {
+
+		if (delegate != null) {
+			return delegate.supports(connectionFactoryOptions);
+		}
+		return false;
+	}
+
+	@Override
+	public String getDriver() {
+
+		if (delegate != null) {
+			return delegate.getDriver();
+		}
+
+		return "oracle-r2dbc (proxy)";
+	}
+
+}

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

@@ -0,0 +1,153 @@
+/*
+ * Copyright 2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.r2dbc.testing;
+
+import io.r2dbc.spi.ConnectionFactories;
+import io.r2dbc.spi.ConnectionFactory;
+import io.r2dbc.spi.ConnectionFactoryOptions;
+
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+
+import javax.sql.DataSource;
+
+import org.springframework.data.r2dbc.testing.ExternalDatabase.ProvidedDatabase;
+import org.springframework.jdbc.datasource.DriverManagerDataSource;
+import org.springframework.util.ClassUtils;
+
+import org.testcontainers.containers.OracleContainer;
+
+/**
+ * Utility class for testing against Oracle.
+ *
+ * @author Mark Paluch
+ */
+public class OracleTestSupport {
+
+	private static ExternalDatabase testContainerDatabase;
+
+	public static String CREATE_TABLE_LEGOSET = "CREATE TABLE legoset (\n" //
+			+ "    id          INTEGER PRIMARY KEY,\n" //
+			+ "    version     INTEGER NULL,\n" //
+			+ "    name        VARCHAR2(255) NOT NULL,\n" //
+			+ "    manual      INTEGER NULL,\n" //
+			+ "    cert        RAW(255) NULL\n" //
+			+ ")";
+
+	public static String CREATE_TABLE_LEGOSET_WITH_ID_GENERATION = "CREATE TABLE legoset (\n" //
+			+ "    id          INTEGER GENERATED by default on null as IDENTITY PRIMARY KEY,\n" //
+			+ "    version     INTEGER NULL,\n" //
+			+ "    name        VARCHAR2(255) NOT NULL,\n" //
+			+ "    manual      INTEGER NULL\n" //
+			+ ")";
+
+	/**
+	 * Returns a database either hosted locally or running inside Docker.
+	 *
+	 * @return information about the database. Guaranteed to be not {@literal null}.
+	 */
+	public static ExternalDatabase database() {
+
+		if (!ClassUtils.isPresent("oracle.r2dbc.impl.OracleConnectionFactoryProviderImpl",
+				OracleTestSupport.class.getClassLoader())) {
+			return ExternalDatabase.unavailable();
+		}
+
+		if (Boolean.getBoolean("spring.data.r2dbc.test.preferLocalDatabase")) {
+
+			return getFirstWorkingDatabase( //
+					OracleTestSupport::local, //
+					OracleTestSupport::testContainer //
+			);
+		} else {
+
+			return getFirstWorkingDatabase( //
+					OracleTestSupport::testContainer, //
+					OracleTestSupport::local //
+			);
+		}
+	}
+
+	@SafeVarargs
+	private static ExternalDatabase getFirstWorkingDatabase(Supplier<ExternalDatabase>... suppliers) {
+
+		return Stream.of(suppliers).map(Supplier::get) //
+				.filter(ExternalDatabase::checkValidity) //
+				.findFirst() //
+				.orElse(ExternalDatabase.unavailable());
+	}
+
+	/**
+	 * Returns a locally provided database.
+	 */
+	private static ExternalDatabase local() {
+
+		return ProvidedDatabase.builder() //
+				.hostname("localhost") //
+				.port(1521) //
+				.database("XEPDB1") //
+				.username("system") //
+				.password("oracle") //
+				.jdbcUrl("jdbc:oracle:thin:system/oracle@localhost:1521:XEPDB1") //
+				.build();
+	}
+
+	/**
+	 * Returns a database provided via Testcontainers.
+	 */
+	private static ExternalDatabase testContainer() {
+
+		if (testContainerDatabase == null) {
+
+			try {
+				OracleContainer container = new OracleContainer("springci/spring-data-oracle-xe-prebuild:18.4.0")
+						.withReuse(true);
+				container.start();
+
+				testContainerDatabase = ProvidedDatabase.builder(container) //
+						.database("XEPDB1").build();
+			} catch (IllegalStateException ise) {
+				// docker not available.
+				testContainerDatabase = ExternalDatabase.unavailable();
+			}
+		}
+
+		return testContainerDatabase;
+	}
+
+	/**
+	 * Creates a new Oracle {@link ConnectionFactory} configured from the {@link ExternalDatabase}.
+	 */
+	public static ConnectionFactory createConnectionFactory(ExternalDatabase database) {
+
+		ConnectionFactoryOptions options = ConnectionUtils.createOptions("oracle", database);
+		return ConnectionFactories.get(options);
+	}
+
+	/**
+	 * Creates a new {@link DataSource} configured from the {@link ExternalDatabase}.
+	 */
+	public static DataSource createDataSource(ExternalDatabase database) {
+
+		DriverManagerDataSource dataSource = new DriverManagerDataSource();
+
+		dataSource.setUsername(database.getUsername());
+		dataSource.setPassword(database.getPassword());
+		dataSource.setUrl(database.getJdbcUrl().replace(":xe", "/XEPDB1"));
+
+		return dataSource;
+	}
+}

src/test/resources/META-INF/services/io.r2dbc.spi.ConnectionFactoryProvider

@@ -0,0 +1,2 @@
+# https://github.com/oracle/oracle-r2dbc/issues/10, otherwise the driver needs to be operated in module-path mode.
+org.springframework.data.r2dbc.testing.OracleConnectionFactoryProviderWrapper