DATAJPA-142 - Allow using a NamedQuery for count queries in pagination.

We will now prefer a declared NamedQuery for count queries instead of deriving it from the actual NamedQuery under the following conditions:

- by default a query named ${namedQueryName}.count exists
- the name of the NamedQuery to be used is defined in @Query(countQueryName = "…")

Note that a potential reconfiguration of the NamedQuery name will be taken into account for the according count query name to assure symmetry. Examples

Page<User> findByLastname(String lastname, Pageable pageable)
NamedQuery name: User.findByLastname
Count NamedQuery name: User.findByLastname.count

@Query(name = "Foo.bar")
Page<User> findByLastname(String lastname, Pageable pageable)
NamedQuery name: Foo.bar
Count NamedQuery name: Foo.bar.count

@Query(countName = "Foo.bar.count")
Page<User> findByLastname(String lastname, Pageable pageable)
NamedQuery name: User.findByLastname
Count NamedQuery name: Foo.bar.count

@Query(name = "Foo.bar", countName = "something")
Page<User> findByLastname(String lastname, Pageable pageable)
NamedQuery name: Foo.bar
Count NamedQuery name: something

src/test/java/org/springframework/data/jpa/repository/query/JpaQueryMethodUnitTests.java

@@ -17,6 +17,7 @@ package org.springframework.data.jpa.repository.query;
 
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
 
 import java.lang.reflect.Method;
 import java.util.List;
@@ -230,6 +231,29 @@ public class JpaQueryMethodUnitTests {
 		assertEquals(LockModeType.PESSIMISTIC_WRITE, lockMode);
 	}
 
+	/**
+	 * @see DATAJPA-142
+	 */
+	@Test
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public void returnsDefaultCountQueryName() {
+
+		when(metadata.getReturnedDomainClass(repositoryMethod)).thenReturn((Class) User.class);
+
+		JpaQueryMethod method = new JpaQueryMethod(repositoryMethod, metadata, extractor);
+		assertThat(method.getNamedCountQueryName(), is("User.findByLastname.count"));
+	}
+
+	/**
+	 * @see DATAJPA-142
+	 */
+	@Test
+	public void returnsDefaultCountQueryNameBasedOnConfiguredNamedQueryName() {
+
+		JpaQueryMethod method = new JpaQueryMethod(namedQuery, metadata, extractor);
+		assertThat(method.getNamedCountQueryName(), is("Foo.bar.count"));
+	}
+
 	/**
 	 * Interface to define invalid repository methods for testing.
 	 * 

src/test/java/org/springframework/data/jpa/repository/query/NamedQueryUnitTests.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.jpa.repository.query;
 
+import static org.mockito.Matchers.*;
 import static org.mockito.Mockito.*;
 
 import java.lang.reflect.Method;
@@ -61,11 +62,29 @@ public class NamedQueryUnitTests {
 	public void rejectsPersistenceProviderIfIncapableOfExtractingQueriesAndPagebleBeingUsed() {
 
 		when(extractor.canExtractQuery()).thenReturn(false);
-
 		JpaQueryMethod queryMethod = new JpaQueryMethod(method, metadata, extractor);
+
+		when(em.createNamedQuery(queryMethod.getNamedCountQueryName())).thenThrow(new IllegalArgumentException());
 		NamedQuery.lookupFrom(queryMethod, em);
 	}
 
+	/**
+	 * @see DATAJPA-142
+	 */
+	@Test
+	public void doesNotRejectPersistenceProviderIfNamedCountQueryIsAvailable() {
+
+		when(extractor.canExtractQuery()).thenReturn(false);
+		JpaQueryMethod queryMethod = new JpaQueryMethod(method, metadata, extractor);
+
+		when(em.createNamedQuery(queryMethod.getNamedCountQueryName())).thenReturn(null);
+		NamedQuery query = (NamedQuery) NamedQuery.lookupFrom(queryMethod, em);
+
+		query.doCreateCountQuery(new Object[1]);
+		verify(em, times(1)).createNamedQuery(queryMethod.getNamedCountQueryName(), Long.class);
+		verify(em, never()).createQuery(any(String.class), eq(Long.class));
+	}
+
 	interface SampleRepository {
 
 		Page<String> foo(Pageable pageable);