feat: add getR2dbcUrl() helper method to JdbcDatabaseContainer

modules/jdbc/src/main/java/org/testcontainers/containers/JdbcDatabaseContainer.java

@@ -77,8 +77,21 @@ public JdbcDatabaseContainer(final DockerImageName dockerImageName) {
     public abstract String getJdbcUrl();
 
     /**
-     * @return the database name
+     * @return a R2DBC URL that may be used to connect to the dockerized DB
      */
+    public String getR2dbcUrl() {
+        String jdbcUrl = getJdbcUrl();
+        if (!jdbcUrl.startsWith("jdbc:")) {
+            throw new IllegalStateException("JDBC URL does not start with 'jdbc:': " + jdbcUrl);
+        }
+        return "r2dbc:" + jdbcUrl.substring(5);
+    }
+
+
+
+        /**
+         * @return the database name
+         */
     public String getDatabaseName() {
         throw new UnsupportedOperationException();
     }

modules/jdbc/src/test/java/org/testcontainers/containers/JdbcDatabaseContainerTest.java

@@ -20,6 +20,32 @@ void anExceptionIsThrownIfJdbcIsNotAvailable() {
         assertThatExceptionOfType(IllegalStateException.class).isThrownBy(jdbcContainer::waitUntilContainerStarted);
     }
 
+    @Test
+    void getR2dbcUrlReturnsR2dbcPrefixedUrl() {
+        JdbcDatabaseContainer<?> jdbcContainer = new JdbcDatabaseContainerStub("mysql:latest") {
+            @Override
+            public String getJdbcUrl() {
+                return "jdbc:mysql://localhost:3306/test";
+            }
+        };
+
+        String r2dbcUrl = jdbcContainer.getR2dbcUrl();
+        assert r2dbcUrl.equals("r2dbc:mysql://localhost:3306/test");
+    }
+
+    @Test
+    void getR2dbcUrlThrowsExceptionIfJdbcPrefixMissing() {
+        JdbcDatabaseContainer<?> jdbcContainer = new JdbcDatabaseContainerStub("mysql:latest") {
+            @Override
+            public String getJdbcUrl() {
+                return "mysql://localhost:3306/test";
+            }
+        };
+
+        assertThatExceptionOfType(IllegalStateException.class)
+            .isThrownBy(jdbcContainer::getR2dbcUrl);
+    }
+
     static class JdbcDatabaseContainerStub extends JdbcDatabaseContainer {
 
         public JdbcDatabaseContainerStub(@NonNull String dockerImageName) {