DATACOUCH-235 - Fixed multiple Couchbase environments.

Defining <couchbase:env/> in XML configuration was causing a double
instantiation of DefaultCoreEnvironment, with subsequent warning in
logs:

[main] WARN c.c.client.core.env.CoreEnvironment - More than 1 Couchbase
Environments found (2), this can have severe impact on performance and
stability. Reuse environments!

src/test/java/org/springframework/data/couchbase/config/CouchbaseSingleEnvironmentParserTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2012-2016 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
+ *
+ *        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.
+ */
+
+package org.springframework.data.couchbase.config;
+
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import org.junit.Test;
+import org.springframework.beans.factory.support.BeanDefinitionReader;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import com.couchbase.client.core.env.DefaultCoreEnvironment;
+import com.couchbase.client.java.env.CouchbaseEnvironment;
+import com.couchbase.client.java.env.DefaultCouchbaseEnvironment;
+
+/**
+ * @author Simon Bland
+ */
+public class CouchbaseSingleEnvironmentParserTest {
+  
+  /**
+   * @see DATACOUCH-235
+   */
+  @Test
+  public void testSingleCouchbaseEnvironment() throws Exception {
+    
+    Integer instanceCounterBefore = (Integer) ReflectionTestUtils.getField(DefaultCoreEnvironment.class, "instanceCounter");
+    
+    DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
+    BeanDefinitionReader reader = new XmlBeanDefinitionReader(factory);
+    reader.loadBeanDefinitions(new ClassPathResource("configurations/couchbaseSingleEnv-bean.xml"));
+    GenericApplicationContext context = new GenericApplicationContext(factory);
+    context.refresh();
+    CouchbaseEnvironment env = context.getBean("singleEnv", CouchbaseEnvironment.class);
+    context.close();
+    
+    Integer instanceCounterAfter = (Integer) ReflectionTestUtils.getField(DefaultCoreEnvironment.class, "instanceCounter");
+    
+    assertThat(env, is(instanceOf(DefaultCouchbaseEnvironment.class)));
+    assertThat(instanceCounterAfter, is(instanceCounterBefore + 1));
+  }
+}