DATAJPA-444 - Improve detection of PersistenceProvider implementations.

Since the location of the Hibernate EntityManager implementation changed in Hibernate 4.3 to org.hibernate.jpa.HibernateEntityManager, we now support org.hibernate.jpa.HibernateEntityManager as well as  org.hibernate.ejb.HibernateEntityManager as a Hibernate PersistenceProvider.

Original pull request: #55.

src/test/java/org/springframework/data/jpa/repository/support/PersistenceProviderTests.java

@@ -0,0 +1,165 @@
+/*
+ * Copyright 2014 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.jpa.repository.support;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.EntityManager;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.springframework.asm.ClassWriter;
+import org.springframework.asm.Opcodes;
+import org.springframework.instrument.classloading.ShadowingClassLoader;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Tests for PersistenceProvider detection logic in {@link PersistenceProvider}.
+ * 
+ * @author Thomas Darimont
+ */
+public class PersistenceProviderTests {
+
+	private ShadowingClassLoader shadowingClassLoader;
+
+	@Before
+	public void setup() {
+		shadowingClassLoader = new ShadowingClassLoader(getClass().getClassLoader());
+	}
+
+	/**
+	 * @see DATAJPA-444
+	 */
+	@Test
+	public void detectsHibernatePersistenceProviderForHibernateVersionLessThan4dot3() throws Exception {
+
+		shadowingClassLoader.excludePackage("org.hibernate");
+
+		EntityManager em = mockProviderSpecificEntityManagerInterface(PersistenceProvider.Constants.HIBERNATE_ENTITY_MANAGER_INTERFACE);
+
+		assertThat(PersistenceProvider.fromEntityManager(em), is(PersistenceProvider.HIBERNATE));
+	}
+
+	/**
+	 * @see DATAJPA-444
+	 */
+	@Test
+	public void detectsHibernatePersistenceProviderForHibernateVersionGreaterEqual4dot3() throws Exception {
+
+		shadowingClassLoader.excludePackage("org.hibernate");
+
+		EntityManager em = mockProviderSpecificEntityManagerInterface(PersistenceProvider.Constants.HIBERNATE43_ENTITY_MANAGER_INTERFACE);
+
+		assertThat(PersistenceProvider.fromEntityManager(em), is(PersistenceProvider.HIBERNATE));
+	}
+
+	@Test
+	public void detectsOpenJpaPersistenceProvider() throws Exception {
+
+		shadowingClassLoader.excludePackage("org.apache.openjpa.persistence");
+
+		EntityManager em = mockProviderSpecificEntityManagerInterface(PersistenceProvider.Constants.OPENJPA_ENTITY_MANAGER_INTERFACE);
+
+		assertThat(PersistenceProvider.fromEntityManager(em), is(PersistenceProvider.OPEN_JPA));
+	}
+
+	@Test
+	public void detectsEclipseLinkPersistenceProvider() throws Exception {
+
+		shadowingClassLoader.excludePackage("org.eclipse.persistence.jpa");
+
+		EntityManager em = mockProviderSpecificEntityManagerInterface(PersistenceProvider.Constants.ECLIPSELINK_ENTITY_MANAGER_INTERFACE);
+
+		assertThat(PersistenceProvider.fromEntityManager(em), is(PersistenceProvider.ECLIPSELINK));
+	}
+
+	@Test
+	public void fallbackToGenericJpaForUnknownPersistenceProvider() throws Exception {
+
+		EntityManager em = mockProviderSpecificEntityManagerInterface("foo.bar.unknown.jpa.JpaEntityManager");
+
+		assertThat(PersistenceProvider.fromEntityManager(em), is(PersistenceProvider.GENERIC_JPA));
+	}
+
+	private EntityManager mockProviderSpecificEntityManagerInterface(String interfaceName) throws ClassNotFoundException {
+
+		Class<?> providerSpecificEntityManagerInterface = InterfaceGenerator.generate(interfaceName, shadowingClassLoader,
+				EntityManager.class);
+
+		EntityManager em = EntityManager.class.cast(Mockito.mock(providerSpecificEntityManagerInterface));
+		Mockito.when(em.getDelegate()).thenReturn(em); // delegate is used to determine the classloader of the provider
+																										// specific interface, therefore we return the proxied
+																										// EntityManager.
+
+		return em;
+	}
+
+	static class InterfaceGenerator implements Opcodes {
+
+		public static Class<?> generate(final String interfaceName, ClassLoader parentClassLoader,
+				final Class<?>... interfaces) throws ClassNotFoundException {
+
+			class CustomClassLoader extends ClassLoader {
+
+				public CustomClassLoader(ClassLoader parent) {
+					super(parent);
+				}
+
+				@Override
+				protected Class<?> findClass(String name) throws ClassNotFoundException {
+
+					if (name.equals(interfaceName)) {
+
+						byte[] byteCode = generateByteCodeForInterface(interfaceName, interfaces);
+						return defineClass(name, byteCode, 0, byteCode.length);
+					}
+
+					return super.findClass(name);
+				}
+			}
+
+			return new CustomClassLoader(parentClassLoader).loadClass(interfaceName);
+		}
+
+		private static byte[] generateByteCodeForInterface(final String interfaceName, Class<?>... interfacesToImplement) {
+
+			String interfaceResourcePath = ClassUtils.convertClassNameToResourcePath(interfaceName);
+
+			ClassWriter cw = new ClassWriter(0);
+			cw.visit(V1_6, ACC_PUBLIC + ACC_ABSTRACT + ACC_INTERFACE, interfaceResourcePath, null, "java/lang/Object",
+					toResourcePaths(interfacesToImplement));
+			cw.visitSource(interfaceResourcePath + ".java", null);
+			cw.visitEnd();
+
+			return cw.toByteArray();
+		}
+
+		private static String[] toResourcePaths(Class<?>... interfacesToImplement) {
+
+			List<String> interfaceResourcePaths = new ArrayList<String>(interfacesToImplement.length);
+			for (Class<?> iface : interfacesToImplement) {
+				interfaceResourcePaths.add(ClassUtils.convertClassNameToResourcePath(iface.getName()));
+			}
+
+			return interfaceResourcePaths.toArray(new String[interfaceResourcePaths.size()]);
+		}
+	}
+}