[#5017] NullPointerException when using MockConnection with DSLContext.transaction()

jOOQ/src/main/java/org/jooq/tools/jdbc/MockConnection.java

@@ -235,13 +235,13 @@ public class MockConnection extends JDBC41Connection implements Connection {
     @Override
     public Savepoint setSavepoint() throws SQLException {
         checkNotClosed();
-        return null;
+        return new MockSavepoint();
     }
 
     @Override
     public Savepoint setSavepoint(String name) throws SQLException {
         checkNotClosed();
-        return null;
+        return new MockSavepoint(name);
     }
 
     @Override

jOOQ/src/main/java/org/jooq/tools/jdbc/MockSavepoint.java

@@ -0,0 +1,70 @@
+/**
+ * Copyright (c) 2009-2016, Data Geekery GmbH (http://www.datageekery.com)
+ * All rights reserved.
+ *
+ * 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
+ *
+ *  http://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.
+ *
+ * Other licenses:
+ * -----------------------------------------------------------------------------
+ * Commercial licenses for this work are available. These replace the above
+ * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
+ * database integrations.
+ *
+ * For more information, please visit: http://www.jooq.org/licenses
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+package org.jooq.tools.jdbc;
+
+import java.sql.SQLException;
+import java.sql.Savepoint;
+
+/**
+ * @author Lukas Eder
+ */
+public class MockSavepoint implements Savepoint {
+
+    private final String name;
+
+    MockSavepoint() {
+        this(null);
+    }
+
+    MockSavepoint(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public int getSavepointId() throws SQLException {
+        return name != null ? name.hashCode() : hashCode();
+    }
+
+    @Override
+    public String getSavepointName() throws SQLException {
+        return name != null ? name : toString();
+    }
+}