Make hasProperty(), hasPropertyAtPath(), samePropertyValuesAs()…

… work for Java Records (#426)

Make hasProperty(), hasPropertyAtPath(), samePropertyValuesAs() work for Java Records

Resolves #392

hamcrest/src/main/java/org/hamcrest/Condition.java

@@ -19,6 +19,7 @@ public abstract class Condition<T> {
      * @param <I> the initial value type
      * @param <O> the next step value type
      */
+    @FunctionalInterface
     public interface Step<I, O> {
         /**
          * Apply this condition to a value

hamcrest/src/main/java/org/hamcrest/beans/HasProperty.java

@@ -3,7 +3,6 @@
 import org.hamcrest.Description;
 import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeMatcher;
-import org.hamcrest.collection.ArrayMatching;
 
 /**
  * A matcher that checks if an object has a JavaBean property with the
@@ -31,7 +30,8 @@ public HasProperty(String propertyName) {
     @Override
     public boolean matchesSafely(T obj) {
         try {
-            return PropertyUtil.getPropertyDescriptor(propertyName, obj) != null;
+            return PropertyUtil.getPropertyDescriptor(propertyName, obj) != null ||
+                    PropertyUtil.getMethodDescriptor(propertyName, obj) != null;
         } catch (IllegalArgumentException e) {
             return false;
         }

hamcrest/src/main/java/org/hamcrest/beans/HasPropertyWithValue.java

@@ -5,6 +5,8 @@
 import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeDiagnosingMatcher;
 
+import java.beans.FeatureDescriptor;
+import java.beans.MethodDescriptor;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -26,7 +28,7 @@
  * <h2>Example Usage</h2>
  * Consider the situation where we have a class representing a person, which
  * follows the basic JavaBean convention of having get() and possibly set()
- * methods for it's properties:
+ * methods for its properties:
  * <pre>{@code  public class Person {
  *   private String name;
  *   public Person(String person) {
@@ -69,7 +71,7 @@
  */
 public class HasPropertyWithValue<T> extends TypeSafeDiagnosingMatcher<T> {
 
-    private static final Condition.Step<PropertyDescriptor, Method> WITH_READ_METHOD = withReadMethod();
+    private static final Condition.Step<FeatureDescriptor, Method> WITH_READ_METHOD = withReadMethod();
     private final String propertyName;
     private final Matcher<Object> valueMatcher;
     private final String messageFormat;
@@ -111,8 +113,11 @@ public void describeTo(Description description) {
                    .appendDescriptionOf(valueMatcher).appendText(")");
     }
 
-    private Condition<PropertyDescriptor> propertyOn(T bean, Description mismatch) {
-        PropertyDescriptor property = PropertyUtil.getPropertyDescriptor(propertyName, bean);
+    private Condition<FeatureDescriptor> propertyOn(T bean, Description mismatch) {
+        FeatureDescriptor property = PropertyUtil.getPropertyDescriptor(propertyName, bean);
+        if (property == null) {
+            property = PropertyUtil.getMethodDescriptor(propertyName, bean);
+        }
         if (property == null) {
             mismatch.appendText("No property \"" + propertyName + "\"");
             return notMatched();
@@ -122,22 +127,19 @@ private Condition<PropertyDescriptor> propertyOn(T bean, Description mismatch) {
     }
 
     private Condition.Step<Method, Object> withPropertyValue(final T bean) {
-        return new Condition.Step<Method, Object>() {
-            @Override
-            public Condition<Object> apply(Method readMethod, Description mismatch) {
-                try {
-                    return matched(readMethod.invoke(bean, NO_ARGUMENTS), mismatch);
-                } catch (InvocationTargetException e) {
-                    mismatch
-                      .appendText("Calling '")
-                      .appendText(readMethod.toString())
-                      .appendText("': ")
-                      .appendValue(e.getTargetException().getMessage());
-                    return notMatched();
-                } catch (Exception e) {
-                    throw new IllegalStateException(
-                      "Calling: '" + readMethod + "' should not have thrown " + e);
-                }
+        return (readMethod, mismatch) -> {
+            try {
+                return matched(readMethod.invoke(bean, NO_ARGUMENTS), mismatch);
+            } catch (InvocationTargetException e) {
+                mismatch
+                  .appendText("Calling '")
+                  .appendText(readMethod.toString())
+                  .appendText("': ")
+                  .appendValue(e.getTargetException().getMessage());
+                return notMatched();
+            } catch (Exception e) {
+                throw new IllegalStateException(
+                  "Calling: '" + readMethod + "' should not have thrown " + e);
             }
         };
     }
@@ -147,17 +149,16 @@ private static Matcher<Object> nastyGenericsWorkaround(Matcher<?> valueMatcher)
         return (Matcher<Object>) valueMatcher;
     }
 
-    private static Condition.Step<PropertyDescriptor, Method> withReadMethod() {
-        return new Condition.Step<PropertyDescriptor, java.lang.reflect.Method>() {
-            @Override
-            public Condition<Method> apply(PropertyDescriptor property, Description mismatch) {
-                final Method readMethod = property.getReadMethod();
-                if (null == readMethod) {
-                    mismatch.appendText("property \"" + property.getName() + "\" is not readable");
-                    return notMatched();
-                }
-                return matched(readMethod, mismatch);
+    private static Condition.Step<FeatureDescriptor, Method> withReadMethod() {
+        return (property, mismatch) -> {
+            final Method readMethod = property instanceof PropertyDescriptor ?
+                    ((PropertyDescriptor) property).getReadMethod() :
+                    (((MethodDescriptor) property).getMethod());
+            if (null == readMethod || readMethod.getReturnType() == void.class) {
+                mismatch.appendText("property \"" + property.getName() + "\" is not readable");
+                return notMatched();
             }
+            return matched(readMethod, mismatch);
         };
     }
 

hamcrest/src/main/java/org/hamcrest/beans/PropertyUtil.java

@@ -2,7 +2,12 @@
 
 import java.beans.IntrospectionException;
 import java.beans.Introspector;
+import java.beans.MethodDescriptor;
 import java.beans.PropertyDescriptor;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * Utility class with static methods for accessing properties on JavaBean objects.
@@ -11,6 +16,7 @@
  *
  * @author Iain McGinniss
  * @author Steve Freeman
+ * @author Uno Kim
  * @since 1.1.0
  */
 public class PropertyUtil {
@@ -27,7 +33,7 @@ private PropertyUtil() {
      * @param fromObj
      *     the object to check.
      * @return the descriptor of the property, or null if the property does not exist.
-     * @throws IllegalArgumentException if there's a introspection failure
+     * @throws IllegalArgumentException if there's an introspection failure
      */
     public static PropertyDescriptor getPropertyDescriptor(String propertyName, Object fromObj) throws IllegalArgumentException {
         for (PropertyDescriptor property : propertyDescriptorsFor(fromObj, null)) {
@@ -45,7 +51,7 @@ public static PropertyDescriptor getPropertyDescriptor(String propertyName, Obje
      * @param fromObj Use the class of this object
      * @param stopClass Don't include any properties from this ancestor class upwards.
      * @return Property descriptors
-     * @throws IllegalArgumentException if there's a introspection failure
+     * @throws IllegalArgumentException if there's an introspection failure
      */
     public static PropertyDescriptor[] propertyDescriptorsFor(Object fromObj, Class<Object> stopClass) throws IllegalArgumentException {
       try {
@@ -55,6 +61,73 @@ public static PropertyDescriptor[] propertyDescriptorsFor(Object fromObj, Class<
       }
     }
 
+    /**
+     * Returns the description of the read accessor method with the provided
+     * name on the provided object's interface.
+     * This is what you need when you try to find a property from a target object
+     * when it doesn't follow standard JavaBean specification, a Java Record for example.
+     *
+     * @param propertyName the object property name.
+     * @param fromObj the object to check.
+     * @return the descriptor of the method, or null if the method does not exist.
+     * @throws IllegalArgumentException if there's an introspection failure
+     * @see <a href="https://docs.oracle.com/en/java/javase/17/language/records.html">Java Records</a>
+     *
+     */
+    public static MethodDescriptor getMethodDescriptor(String propertyName, Object fromObj) throws IllegalArgumentException {
+        for (MethodDescriptor method : recordReadAccessorMethodDescriptorsFor(fromObj, null)) {
+            if (method.getName().equals(propertyName)) {
+                return method;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Returns read accessor method descriptors for the class associated with the given object.
+     * This is useful when you find getter methods for the fields from the object
+     * when it doesn't follow standard JavaBean specification, a Java Record for example.
+     * Be careful as this doesn't return standard JavaBean getter methods, like a method starting with {@code get-}.
+     *
+     * @param fromObj Use the class of this object
+     * @param stopClass Don't include any properties from this ancestor class upwards.
+     * @return Method descriptors for read accessor methods
+     * @throws IllegalArgumentException if there's an introspection failure
+     */
+    public static MethodDescriptor[] recordReadAccessorMethodDescriptorsFor(Object fromObj, Class<Object> stopClass) throws IllegalArgumentException {
+        try {
+            Set<String> recordComponentNames = getFieldNames(fromObj);
+            MethodDescriptor[] methodDescriptors = Introspector.getBeanInfo(fromObj.getClass(), stopClass).getMethodDescriptors();
+
+            return Arrays.stream(methodDescriptors)
+                    .filter(x -> recordComponentNames.contains(x.getDisplayName()))
+                    .filter(x -> x.getMethod().getReturnType() != void.class)
+                    .filter(x -> x.getMethod().getParameterCount() == 0)
+                    .toArray(MethodDescriptor[]::new);
+        } catch (IntrospectionException e) {
+            throw new IllegalArgumentException("Could not get method descriptors for " + fromObj.getClass(), e);
+        }
+    }
+
+    /**
+     * Returns the field names of the given object.
+     * It can be the names of the record components of Java Records, for example.
+     *
+     * @param fromObj the object to check
+     * @return The field names
+     * @throws IllegalArgumentException if there's a security issue reading the fields
+     */
+    public static Set<String> getFieldNames(Object fromObj) throws IllegalArgumentException {
+        try {
+            return Arrays.stream(fromObj.getClass().getDeclaredFields())
+                    .map(Field::getName)
+                    .collect(Collectors.toSet());
+        } catch (SecurityException e) {
+            throw new IllegalArgumentException("Could not get record component names for " + fromObj.getClass(), e);
+        }
+    }
+
     /**
      * Empty object array, used for documenting that we are deliberately passing no arguments to a method.
      */

hamcrest/src/main/java/org/hamcrest/beans/SamePropertyValuesAs.java

@@ -4,13 +4,16 @@
 import org.hamcrest.DiagnosingMatcher;
 import org.hamcrest.Matcher;
 
+import java.beans.FeatureDescriptor;
+import java.beans.MethodDescriptor;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Method;
 import java.util.*;
 
 import static java.util.Arrays.asList;
 import static org.hamcrest.beans.PropertyUtil.NO_ARGUMENTS;
 import static org.hamcrest.beans.PropertyUtil.propertyDescriptorsFor;
+import static org.hamcrest.beans.PropertyUtil.recordReadAccessorMethodDescriptorsFor;
 import static org.hamcrest.core.IsEqual.equalTo;
 
 /**
@@ -33,7 +36,11 @@ public class SamePropertyValuesAs<T> extends DiagnosingMatcher<T> {
      */
     @SuppressWarnings("WeakerAccess")
     public SamePropertyValuesAs(T expectedBean, List<String> ignoredProperties) {
-        PropertyDescriptor[] descriptors = propertyDescriptorsFor(expectedBean, Object.class);
+        FeatureDescriptor[] descriptors = propertyDescriptorsFor(expectedBean, Object.class);
+        if (descriptors == null || descriptors.length == 0) {
+            descriptors = recordReadAccessorMethodDescriptorsFor(expectedBean, Object.class);
+        }
+
         this.expectedBean = expectedBean;
         this.ignoredFields = ignoredProperties;
         this.propertyNames = propertyNamesFrom(descriptors, ignoredProperties);
@@ -87,27 +94,27 @@ private boolean hasMatchingValues(Object actual, Description mismatchDescription
         return true;
     }
 
-    private static <T> List<PropertyMatcher> propertyMatchersFor(T bean, PropertyDescriptor[] descriptors, List<String> ignoredFields) {
+    private static <T> List<PropertyMatcher> propertyMatchersFor(T bean, FeatureDescriptor[] descriptors, List<String> ignoredFields) {
         List<PropertyMatcher> result = new ArrayList<>(descriptors.length);
-        for (PropertyDescriptor propertyDescriptor : descriptors) {
-            if (isIgnored(ignoredFields, propertyDescriptor)) {
-                result.add(new PropertyMatcher(propertyDescriptor, bean));
+        for (FeatureDescriptor descriptor : descriptors) {
+            if (isNotIgnored(ignoredFields, descriptor)) {
+                result.add(new PropertyMatcher(descriptor, bean));
             }
         }
         return result;
     }
 
-    private static Set<String> propertyNamesFrom(PropertyDescriptor[] descriptors, List<String> ignoredFields) {
+    private static Set<String> propertyNamesFrom(FeatureDescriptor[] descriptors, List<String> ignoredFields) {
         HashSet<String> result = new HashSet<>();
-        for (PropertyDescriptor propertyDescriptor : descriptors) {
-            if (isIgnored(ignoredFields, propertyDescriptor)) {
-                result.add(propertyDescriptor.getDisplayName());
+        for (FeatureDescriptor descriptor : descriptors) {
+            if (isNotIgnored(ignoredFields, descriptor)) {
+                result.add(descriptor.getDisplayName());
             }
         }
         return result;
     }
 
-    private static boolean isIgnored(List<String> ignoredFields, PropertyDescriptor propertyDescriptor) {
+    private static boolean isNotIgnored(List<String> ignoredFields, FeatureDescriptor propertyDescriptor) {
         return ! ignoredFields.contains(propertyDescriptor.getDisplayName());
     }
 
@@ -117,9 +124,11 @@ private static class PropertyMatcher extends DiagnosingMatcher<Object> {
         private final Matcher<Object> matcher;
         private final String propertyName;
 
-        public PropertyMatcher(PropertyDescriptor descriptor, Object expectedObject) {
+        public PropertyMatcher(FeatureDescriptor descriptor, Object expectedObject) {
             this.propertyName = descriptor.getDisplayName();
-            this.readMethod = descriptor.getReadMethod();
+            this.readMethod = descriptor instanceof PropertyDescriptor ?
+                    ((PropertyDescriptor) descriptor).getReadMethod() :
+                    ((MethodDescriptor) descriptor).getMethod();
             this.matcher = equalTo(readProperty(readMethod, expectedObject));
         }
 

hamcrest/src/test/java/org/hamcrest/beans/HasPropertyTest.java

@@ -16,6 +16,7 @@
 public final class HasPropertyTest {
 
     private final HasPropertyWithValueTest.BeanWithoutInfo bean = new HasPropertyWithValueTest.BeanWithoutInfo("a bean", false);
+    private final HasPropertyWithValueTest.RecordLikeBeanWithoutInfo record = new HasPropertyWithValueTest.RecordLikeBeanWithoutInfo("a record", false);
 
     @Test public void
     copesWithNullsAndUnknownTypes() {
@@ -28,11 +29,14 @@ public final class HasPropertyTest {
     @Test public void
     matchesWhenThePropertyExists() {
         assertMatches(hasProperty("writeOnlyProperty"), bean);
+        assertMatches(hasProperty("property"), record);
     }
 
     @Test public void
     doesNotMatchIfPropertyDoesNotExist() {
         assertDoesNotMatch(hasProperty("aNonExistentProp"), bean);
+        assertDoesNotMatch(hasProperty("aNonExistentProp"), record);
+        assertDoesNotMatch(hasProperty("notAGetterMethod"), record);
     }
 
     @Test public void
@@ -44,6 +48,8 @@ public final class HasPropertyTest {
     describesAMismatch() {
         assertMismatchDescription("no \"aNonExistentProp\" in <[Person: a bean]>",
                                   hasProperty("aNonExistentProp"), bean);
+        assertMismatchDescription("no \"aNonExistentProp\" in <[Person: a record]>",
+                                  hasProperty("aNonExistentProp"), record);
     }
 
 }