DATACMNS-1289 - Allow fragment creation only from implementations that implement their declared class.

pom.xml

@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-commons</artifactId>
-	<version>2.1.0.BUILD-SNAPSHOT</version>
+	<version>2.1.0.DATACMNS-1289-SNAPSHOT</version>
 
 	<name>Spring Data Core</name>
 

src/main/java/org/springframework/data/repository/core/support/RepositoryFragment.java

@@ -155,12 +155,27 @@ public String toString() {
 		}
 	}
 
-	@RequiredArgsConstructor
 	@EqualsAndHashCode(callSuper = false)
 	static class ImplementedRepositoryFragment<T> implements RepositoryFragment<T> {
 
-		private final @NonNull Optional<Class<T>> interfaceClass;
-		private final @NonNull T implementation;
+		private final Optional<Class<T>> interfaceClass;
+		private final T implementation;
+
+		public ImplementedRepositoryFragment(Optional<Class<T>> interfaceClass, T implementation) {
+
+			Assert.notNull(interfaceClass, "Interface class must not be null!");
+			Assert.notNull(implementation, "Implementation object must not be null!");
+
+			interfaceClass.ifPresent(it -> {
+
+				Assert.isTrue(ClassUtils.isAssignableValue(it, implementation),
+						() -> String.format("Fragment implementation %s does not implement %s!", ClassUtils.getQualifiedName(it),
+								ClassUtils.getQualifiedName(implementation.getClass())));
+			});
+
+			this.interfaceClass = interfaceClass;
+			this.implementation = implementation;
+		}
 
 		/*
 		 * (non-Javadoc)

src/test/java/org/springframework/data/repository/core/support/RepositoryFragmentUnitTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2018 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.repository.core.support;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.Test;
+
+/**
+ * Unit tests for {@link RepositoryFragment}.
+ *
+ * @author Mark Paluch
+ */
+public class RepositoryFragmentUnitTests {
+
+	@SuppressWarnings("unchecked")
+	@Test // DATACMNS-1289
+	public void fragmentCreationFromUnrelatedTypesShouldFail() {
+
+		assertThatThrownBy(() -> RepositoryFragment.implemented((Class) CustomFragment.class, new UnrelatedImpl()))
+				.hasMessageMatching("Fragment implementation .* does not implement .*UnrelatedImpl!")
+				.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test // DATACMNS-1289
+	public void fragmentCreationFromRelatedTypesShouldCreateNewFragment() {
+		assertThat(RepositoryFragment.implemented(CustomFragment.class, new CustomFragmentImpl())).isNotNull();
+	}
+
+	interface CustomFragment {}
+
+	private static class CustomFragmentImpl implements CustomFragment {}
+
+	private static class UnrelatedImpl {}
+}