DATACMNS-387 - Improvements in null handling in PartTree area.

We're now rejecting invalid constructor arguments handed to ClassTypeInformation, Part, PartTree and PropertyPath. Beyond that we skip the creation of a Part for an empty path segment, so that you don't end up with an invalid Part instance for a findAllByOrderByFooAsc.

src/main/java/org/springframework/data/mapping/PropertyPath.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -52,7 +52,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @param owningType must not be {@literal null}.
 	 */
 	PropertyPath(String name, Class<?> owningType) {
-
 		this(name, ClassTypeInformation.from(owningType), null);
 	}
 
@@ -132,7 +131,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @see #hasNext()
 	 */
 	public PropertyPath next() {
-
 		return next;
 	}
 
@@ -143,7 +141,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public boolean hasNext() {
-
 		return next != null;
 	}
 
@@ -167,7 +164,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public boolean isCollection() {
-
 		return isCollection;
 	}
 
@@ -241,7 +237,6 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 * @return
 	 */
 	public static PropertyPath from(String source, Class<?> type) {
-
 		return from(source, ClassTypeInformation.from(type));
 	}
 
@@ -254,6 +249,9 @@ public class PropertyPath implements Iterable<PropertyPath> {
 	 */
 	public static PropertyPath from(String source, TypeInformation<?> type) {
 
+		Assert.hasText(source, "Source must not be null or empty!");
+		Assert.notNull(type, "TypeInformation must not be null or empty!");
+
 		List<String> iteratorSource = new ArrayList<String>();
 		Matcher matcher = SPLITTER.matcher("_" + source);
 

src/main/java/org/springframework/data/repository/query/parser/Part.java

@@ -24,6 +24,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.springframework.data.mapping.PropertyPath;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -46,25 +47,27 @@ public class Part {
 	 * Creates a new {@link Part} from the given method name part, the {@link Class} the part originates from and the
 	 * start parameter index.
 	 * 
-	 * @param part must not be {@literal null}.
+	 * @param source must not be {@literal null}.
 	 * @param clazz must not be {@literal null}.
 	 */
-	public Part(String part, Class<?> clazz) {
-
-		this(part, clazz, false);
+	public Part(String source, Class<?> clazz) {
+		this(source, clazz, false);
 	}
 
 	/**
 	 * Creates a new {@link Part} from the given method name part, the {@link Class} the part originates from and the
 	 * start parameter index.
 	 * 
-	 * @param part must not be {@literal null}.
+	 * @param source must not be {@literal null}.
 	 * @param clazz must not be {@literal null}.
 	 * @param alwaysIgnoreCase
 	 */
-	public Part(String part, Class<?> clazz, boolean alwaysIgnoreCase) {
+	public Part(String source, Class<?> clazz, boolean alwaysIgnoreCase) {
 
-		String partToUse = detectAndSetIgnoreCase(part);
+		Assert.hasText(source, "Part source must not be null or emtpy!");
+		Assert.notNull(clazz, "Type must not be null!");
+
+		String partToUse = detectAndSetIgnoreCase(source);
 		if (alwaysIgnoreCase && ignoreCase != IgnoreCaseType.ALWAYS) {
 			this.ignoreCase = IgnoreCaseType.WHEN_POSSIBLE;
 		}

src/main/java/org/springframework/data/repository/query/parser/PartTree.java

@@ -185,7 +185,9 @@ public class PartTree implements Iterable<OrPart> {
 
 			String[] split = split(source, "And");
 			for (String part : split) {
-				children.add(new Part(part, domainClass, alwaysIgnoreCase));
+				if (StringUtils.hasText(part)) {
+					children.add(new Part(part, domainClass, alwaysIgnoreCase));
+				}
 			}
 		}
 

src/main/java/org/springframework/data/util/ClassTypeInformation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -29,6 +29,7 @@ import java.util.Set;
 import java.util.WeakHashMap;
 
 import org.springframework.core.GenericTypeResolver;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -60,11 +61,13 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 	 * Simple factory method to easily create new instances of {@link ClassTypeInformation}.
 	 * 
 	 * @param <S>
-	 * @param type
+	 * @param type must not be {@literal null}.
 	 * @return
 	 */
 	public static <S> TypeInformation<S> from(Class<S> type) {
 
+		Assert.notNull(type, "Type must not be null!");
+
 		Reference<TypeInformation<?>> cachedReference = CACHE.get(type);
 		TypeInformation<?> cachedTypeInfo = cachedReference == null ? null : cachedReference.get();
 
@@ -80,10 +83,12 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 	/**
 	 * Creates a {@link TypeInformation} from the given method's return type.
 	 * 
-	 * @param method
+	 * @param method must not be {@literal null}.
 	 * @return
 	 */
 	public static <S> TypeInformation<S> fromReturnTypeOf(Method method) {
+
+		Assert.notNull(method, "Method must not be null!");
 		return new ClassTypeInformation(method.getDeclaringClass()).createInfo(method.getGenericReturnType());
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012 the original author or authors.
+ * Copyright 2011-2013 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.
@@ -17,6 +17,7 @@ package org.springframework.data.mapping;
 
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
+import static org.springframework.data.mapping.PropertyPath.*;
 
 import java.util.Iterator;
 import java.util.Map;
@@ -307,6 +308,51 @@ public class PropertyPathUnitTests {
 		assertThat(path.next().getSegment(), is("UUID"));
 	}
 
+	/**
+	 * @see DATACMNS-381
+	 */
+	public void exposesPreviouslyReferencedPathInExceptionMessage() {
+
+		exception.expect(PropertyReferenceException.class);
+		exception.expectMessage("bar"); // missing variable
+		exception.expectMessage("String"); // type
+		exception.expectMessage("Bar.user.name"); // previously referenced path
+
+		PropertyPath.from("userNameBar", Bar.class);
+	}
+
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullSource() {
+		from(null, Foo.class);
+	}
+
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsEmptySource() {
+		from("", Foo.class);
+	}
+
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullClass() {
+		from("foo", (Class<?>) null);
+	}
+
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullTypeInformation() {
+		from("foo", (TypeInformation<?>) null);
+	}
+
 	private class Foo {
 
 		String userName;

src/test/java/org/springframework/data/repository/query/parser/PartTreeUnitTests.java

@@ -374,6 +374,18 @@ public class PartTreeUnitTests {
 		assertThat(new PartTree("findByAnders", Product.class), is(notNullValue()));
 	}
 
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test
+	public void buildsPartTreeFromEmptyPredicateCorrectly() {
+
+		PartTree tree = new PartTree("findAllByOrderByLastnameAsc", User.class);
+
+		assertThat(tree.getParts(), is(emptyIterable()));
+		assertThat(tree.getSort(), is(new Sort(Direction.ASC, "lastname")));
+	}
+
 	private static void assertType(Iterable<String> sources, Type type, String property) {
 		assertType(sources, type, property, 1, true);
 	}

src/test/java/org/springframework/data/util/ClassTypeInformationUnitTests.java

@@ -277,6 +277,14 @@ public class ClassTypeInformationUnitTests {
 		assertThat(categoryIdInfo, is((TypeInformation) from(Long.class)));
 	}
 
+	/**
+	 * @see DATACMNS-387
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullClass() {
+		from(null);
+	}
+
 	static class StringMapContainer extends MapContainer<String> {
 
 	}