diff --git a/src/test/org/apache/http/impl/conn/ClientConnAdapterMockup.java b/src/test/org/apache/http/impl/conn/ClientConnAdapterMockup.java
new file mode 100644
index 000000000..9b656f852
--- /dev/null
+++ b/src/test/org/apache/http/impl/conn/ClientConnAdapterMockup.java
@@ -0,0 +1,73 @@
+/*
+ * $HeadURL$
+ * $Revision$
+ * $Date$
+ * ====================================================================
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+
+package org.apache.http.impl.conn;
+
+import org.apache.http.params.HttpParams;
+import org.apache.http.protocol.HttpContext;
+import org.apache.http.conn.HttpRoute;
+
+
+/**
+ * Mockup connection adapter.
+ */
+public class ClientConnAdapterMockup extends AbstractClientConnAdapter {
+
+    private boolean open = true;
+    
+    public ClientConnAdapterMockup() {
+        super(null, null);
+    }
+
+    public void close() {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+    public HttpRoute getRoute() {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+    public void layerProtocol(HttpContext context, HttpParams params) {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+    public void open(HttpRoute route, HttpContext context, HttpParams params) {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+    public void shutdown() {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+    public void tunnelCreated(boolean secure, HttpParams params) {
+        throw new UnsupportedOperationException("just a mockup");
+    }
+
+}
diff --git a/src/test/org/apache/http/impl/conn/TestTSCCMNoServer.java b/src/test/org/apache/http/impl/conn/TestTSCCMNoServer.java
index 418baa403..f96ba6c14 100644
--- a/src/test/org/apache/http/impl/conn/TestTSCCMNoServer.java
+++ b/src/test/org/apache/http/impl/conn/TestTSCCMNoServer.java
@@ -169,6 +169,14 @@ public class TestTSCCMNoServer extends TestCase {
         assertFalse(conn.isOpen());
 
         mgr.releaseConnection(conn);
+
+        try {
+            conn = mgr.getConnection(null);
+            fail("null route not detected");
+        } catch (IllegalArgumentException iax) {
+            // expected
+        }
+
         mgr.shutdown();
     }
 
@@ -271,6 +279,21 @@ public class TestTSCCMNoServer extends TestCase {
             // expected
         }
 
+
+        // check releaseConnection with invalid arguments
+        try {
+            mgr.releaseConnection(null);
+            fail("null connection adapter not detected");
+        } catch (IllegalArgumentException iax) {
+            // expected
+        }
+        try {
+            mgr.releaseConnection(new ClientConnAdapterMockup());
+            fail("foreign connection adapter not detected");
+        } catch (IllegalArgumentException iax) {
+            // expected
+        }
+
         mgr.shutdown();
     }