Add support for TCP connections to remote H2 instances.

Resolves #86.

src/main/java/io/r2dbc/h2/H2ConnectionConfiguration.java

@@ -121,6 +121,29 @@ public Builder inMemory(String name) {
             return url(String.format("mem:%s", name));
         }
 
+        /**
+         * Configure a TCP connection to a remote database.
+         *
+         * @param host - hostname of the remote database (can be {@code localhost})
+         * @param path - path of the database, e.g. {@code ~/test} resolves to {user.home}/test.db
+         * @return this {@link Builder}
+         */
+        public Builder tcp(String host, String path) {
+            return url(String.format("tcp://%s/%s", host, path));
+        }
+
+        /**
+         * Configure a TCP connection to a remote database
+         *
+         * @param host - hostname of the remote database (can be {@code localhost})
+         * @param port - port the database is serving from
+         * @param path - path of the database, e.g. {@code ~/test} resolves to {user.home}/test.db
+         * @return this {@link Builder}
+         */
+        public Builder tcp(String host, String port, String path) {
+            return url(String.format("tcp://%s:%s/%s", host, port, path));
+        }
+
         /**
          * Configure an option that is appended at the end, e.g. {@code DB_CLOSE_DELAY=10}, prefixed with ";".
          *

src/test/java/io/r2dbc/h2/H2RemoteAccessTest.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2019 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 io.r2dbc.h2;
+
+import org.h2.tools.Server;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.util.FileSystemUtils;
+import reactor.test.StepVerifier;
+
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.sql.SQLException;
+
+final class H2RemoteAccessTest {
+
+    Server server;
+
+    @BeforeEach
+    void startupRemoteDatabase() throws SQLException {
+        server = Server.createTcpServer("-tcpPort", "9123", "-ifNotExists").start();
+    }
+
+    @AfterEach
+    void shutdownRemoteDatabase() {
+        server.stop();
+    }
+
+    @Test
+    void tcpByUrlWorks() throws IOException {
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+
+        H2ConnectionConfiguration configuration = H2ConnectionConfiguration.builder()
+            .url("tcp://localhost:9123/~/test")
+            .username("sa")
+            .password("")
+            .build();
+
+        new H2ConnectionFactory(configuration).create()
+            .as(StepVerifier::create)
+            .expectNextCount(1)
+            .verifyComplete();
+
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+    }
+
+    @Test
+    void tcpWithHostnameAndPortWorks() throws IOException {
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+
+        H2ConnectionConfiguration configuration = H2ConnectionConfiguration.builder()
+            .tcp("localhost", "9123", "~/test")
+            .username("sa")
+            .password("")
+            .build();
+
+        new H2ConnectionFactory(configuration).create()
+            .as(StepVerifier::create)
+            .expectNextCount(1)
+            .verifyComplete();
+
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+    }
+
+    @Test
+    void tcpWithHostnameButNoPortWorks() throws IOException, SQLException {
+
+        // Stopping the default one...
+        server.stop();
+
+        // ...to launch another one with the default port
+        server = Server.createTcpServer("-ifNotExists").start();
+
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+
+
+
+        H2ConnectionConfiguration configuration = H2ConnectionConfiguration.builder()
+            .tcp("localhost", "~/test")
+            .username("sa")
+            .password("")
+            .build();
+
+        new H2ConnectionFactory(configuration).create()
+            .as(StepVerifier::create)
+            .expectNextCount(1)
+            .verifyComplete();
+
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.mv.db"));
+        FileSystemUtils.deleteRecursively(Paths.get(System.getProperty("user.home"), "test.trace.db"));
+    }
+}