DATACMNS-801 - Make sure PropertyReferenceException does not expose duplicate potential matches.

We now use a Set to collect potential matches from fields and accessors.

Polished assertions and JavaDoc in PropertyPath along the way.

src/test/java/org/springframework/data/mapping/PropertyReferenceExceptionUnitTests.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 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.mapping;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
+
+/**
+ * Unit tests for {@link PropertyReferenceException}
+ *
+ * @author Oliver Gierke
+ */
+public class PropertyReferenceExceptionUnitTests {
+
+	static final TypeInformation<Sample> TYPE_INFO = ClassTypeInformation.from(Sample.class);
+	static final List<PropertyPath> NO_PATHS = Collections.emptyList();
+
+	public @Rule ExpectedException exception = ExpectedException.none();
+
+	@Test
+	public void rejectsNullPropertyName() {
+
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage("name");
+
+		new PropertyReferenceException(null, TYPE_INFO, NO_PATHS);
+	}
+
+	@Test
+	public void rejectsNullType() {
+
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage("Type");
+
+		new PropertyReferenceException("nme", null, NO_PATHS);
+	}
+
+	@Test
+	public void rejectsNullPaths() {
+
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage("paths");
+
+		new PropertyReferenceException("nme", TYPE_INFO, null);
+	}
+
+	/**
+	 * @see DATACMNS-801
+	 */
+	@Test
+	public void exposesPotentialMatch() {
+
+		PropertyReferenceException exception = new PropertyReferenceException("nme", TYPE_INFO, NO_PATHS);
+
+		Collection<String> matches = exception.getPropertyMatches();
+
+		assertThat(matches, hasSize(1));
+		assertThat(matches, hasItem("name"));
+	}
+
+	static class Sample {
+
+		String name;
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+	}
+}