Rebuild of PropertyAccessor

Author: tumbarumba

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

@@ -30,7 +30,8 @@ public HasProperty(String propertyName) {
     @Override
     public boolean matchesSafely(T obj) {
         try {
-            return PropertyUtil.getPropertyAccessor(propertyName, obj) != null;
+            PropertyAccessor accessor = new PropertyAccessor(obj);
+            return accessor.fieldNames().contains(propertyName);
         } catch (IllegalArgumentException e) {
             return false;
         }

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

@@ -4,7 +4,7 @@
 import org.hamcrest.Description;
 import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeDiagnosingMatcher;
-import org.hamcrest.beans.PropertyUtil.PropertyAccessor;
+import org.hamcrest.beans.PropertyAccessor.PropertyReadLens;
 
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -69,7 +69,7 @@
  */
 public class HasPropertyWithValue<T> extends TypeSafeDiagnosingMatcher<T> {
 
-    private static final Condition.Step<PropertyAccessor, Method> WITH_READ_METHOD = withReadMethod();
+    private static final Condition.Step<PropertyReadLens, Method> WITH_READ_METHOD = withReadMethod();
     private final String propertyName;
     private final Matcher<Object> valueMatcher;
     private final String messageFormat;
@@ -111,14 +111,14 @@ public void describeTo(Description description) {
                    .appendDescriptionOf(valueMatcher).appendText(")");
     }
 
-    private Condition<PropertyAccessor> propertyOn(T bean, Description mismatch) {
-        PropertyAccessor property = PropertyUtil.getPropertyAccessor(propertyName, bean);
-        if (property == null) {
+    private Condition<PropertyReadLens> propertyOn(T bean, Description mismatch) {
+        PropertyAccessor accessor = new PropertyAccessor(bean);
+        if (!accessor.fieldNames().contains(propertyName)) {
             mismatch.appendText("No property \"" + propertyName + "\"");
             return notMatched();
         }
 
-        return matched(property, mismatch);
+        return matched(accessor.readLensFor(propertyName), mismatch);
     }
 
     private Condition.Step<Method, Object> withPropertyValue(final T bean) {
@@ -144,11 +144,11 @@ private static Matcher<Object> nastyGenericsWorkaround(Matcher<?> valueMatcher)
         return (Matcher<Object>) valueMatcher;
     }
 
-    private static Condition.Step<PropertyAccessor, Method> withReadMethod() {
-        return (accessor, mismatch) -> {
-            final Method readMethod = accessor.readMethod();
+    private static Condition.Step<PropertyReadLens, Method> withReadMethod() {
+        return (readLens, mismatch) -> {
+            final Method readMethod = readLens.getReadMethod();
             if (null == readMethod || readMethod.getReturnType() == void.class) {
-                mismatch.appendText("property \"" + accessor.propertyName() + "\" is not readable");
+                mismatch.appendText("property \"" + readLens.getName() + "\" is not readable");
                 return notMatched();
             }
             return matched(readMethod, mismatch);

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

@@ -0,0 +1,194 @@
+package org.hamcrest.beans;
+
+import java.beans.IntrospectionException;
+import java.beans.Introspector;
+import java.beans.MethodDescriptor;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.*;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+/**
+ * Utility class to help with finding properties in an object.
+ * <p>
+ * The properties can be either properties as described by the
+ * JavaBean specification and APIs, or it will fall back to finding
+ * fields with corresponding methods, enabling the property matchers
+ * to work with newer classes like Records.
+ */
+public class PropertyAccessor {
+    private final Object beanLikeObject;
+    private final SortedMap<String, PropertyReadLens> readLenses;
+
+    /**
+     * Constructor.
+     * @param beanLikeObject the object to search for properties.
+     */
+    public PropertyAccessor(Object beanLikeObject) {
+        this.beanLikeObject = beanLikeObject;
+        this.readLenses = new TreeMap<>(makeLensesFor(beanLikeObject));
+    }
+
+    private Map<String, PropertyReadLens> makeLensesFor(Object bean) {
+        PropertyDescriptor[] properties = PropertyUtil.propertyDescriptorsFor(bean, Object.class);
+        if (properties != null && properties.length > 0) {
+            return makePropertyLensesFrom(properties);
+        }
+
+        return makeFieldMethodLensesFor(bean);
+    }
+
+    private Map<String, PropertyReadLens> makePropertyLensesFrom(PropertyDescriptor[] descriptors) {
+        return Arrays.stream(descriptors)
+                .map(pd -> new PropertyReadLens(pd.getDisplayName(), pd.getReadMethod()))
+                .collect(Collectors.toMap(PropertyReadLens::getName, Function.identity()));
+    }
+
+    private Map<String, PropertyReadLens> makeFieldMethodLensesFor(Object bean) {
+        try {
+            Set<String> fieldNames = getFieldNames(bean);
+            MethodDescriptor[] methodDescriptors = Introspector.getBeanInfo(bean.getClass(), null).getMethodDescriptors();
+            return Arrays.stream(methodDescriptors)
+                    .filter(IsPropertyAccessor.forOneOf(fieldNames))
+                    .map(md -> new PropertyReadLens(md.getDisplayName(), md.getMethod()))
+                    .collect(Collectors.toMap(PropertyReadLens::getName, Function.identity()));
+        }
+        catch (IntrospectionException e) {
+            throw new IllegalArgumentException("Could not get method descriptors for " + bean.getClass(), e);
+        }
+    }
+
+    /**
+     * The names of properties that were found in the object.
+     * @return a set of field names
+     */
+    public Set<String> fieldNames() {
+        return readLenses.keySet();
+    }
+
+    /**
+     * The collection of lenses for all the properties that were found in the
+     * object.
+     * @return the collection of lenses
+     */
+    public Collection<PropertyReadLens> readLenses() {
+        return readLenses.values();
+    }
+
+    /**
+     * The read lens for the specified property.
+     * @param propertyName the property to find the lens for.
+     * @return the read lens for the property
+     */
+    public PropertyReadLens readLensFor(String propertyName) {
+        return readLenses.get(propertyName);
+    }
+
+    /**
+     * The value of the specified property.
+     * @param propertyName the name of the property
+     * @return the value of the given property name.
+     */
+    public Object fieldValue(String propertyName) {
+        PropertyReadLens lens = readLenses.get(propertyName);
+        if (lens == null) {
+            String message = String.format("Unknown property '%s' for bean '%s'", propertyName, beanLikeObject);
+            throw new IllegalArgumentException(message);
+        }
+        return lens.getValue();
+    }
+
+    /**
+     * 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
+     */
+    private 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);
+        }
+    }
+
+
+    /**
+     * Predicate that checks if a given {@link MethodDescriptor} corresponds to a field.
+     * <p>
+     * This predicate assumes a method is a field access if the method name exactly
+     * matches the field name, takes no parameters and returns a non-void type.
+     */
+    private static class IsPropertyAccessor implements Predicate<MethodDescriptor> {
+        private final Set<String> propertyNames;
+
+        private IsPropertyAccessor(Set<String> propertyNames) {
+            this.propertyNames = propertyNames;
+        }
+
+        public static IsPropertyAccessor forOneOf(Set<String> propertyNames) {
+            return new IsPropertyAccessor(propertyNames);
+        }
+
+        @Override
+        public boolean test(MethodDescriptor md) {
+            return propertyNames.contains(md.getDisplayName()) &&
+                    md.getMethod().getReturnType() != void.class &&
+                    md.getMethod().getParameterCount() == 0;
+        }
+    }
+
+    /**
+     * Encapsulates a property in the parent object.
+     */
+    public class PropertyReadLens {
+        private final String name;
+        private final Method readMethod;
+
+        /**
+         * Constructor.
+         * @param name the name of the property
+         * @param readMethod the method that can be used to get the value of the property
+         */
+        public PropertyReadLens(String name, Method readMethod) {
+            this.name = name;
+            this.readMethod = readMethod;
+        }
+
+        /**
+         * The name of the property
+         * @return the name of the property.
+         */
+        public String getName() {
+            return name;
+        }
+
+        /**
+         * The read method for the property.
+         * @return the read method for the property.
+         */
+        public Method getReadMethod() {
+            return readMethod;
+        }
+
+        /**
+         * The value of the property.
+         * @return the value of the property.
+         */
+        public Object getValue() {
+            Object bean = PropertyAccessor.this.beanLikeObject;
+            try {
+                return readMethod.invoke(bean, PropertyUtil.NO_ARGUMENTS);
+            } catch (Exception e) {
+                throw new IllegalArgumentException("Could not invoke " + readMethod + " on " + bean, e);
+            }
+        }
+    }
+}