/*
    * Copyright (C) 2012 The Guava 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 com.google.common.testing;
  
  import static com.google.common.base.Predicates.and;
  import static com.google.common.base.Predicates.not;
  import static com.google.common.testing.AbstractPackageSanityTests.Chopper.suffix;
  
  import com.google.common.annotations.Beta;
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.base.Optional;
  import com.google.common.base.Predicate;
  import com.google.common.collect.HashMultimap;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.Iterables;
  import com.google.common.collect.Lists;
  import com.google.common.collect.Maps;
  import com.google.common.collect.Multimap;
  import com.google.common.collect.Sets;
  import com.google.common.reflect.ClassPath;
  import com.google.common.testing.NullPointerTester.Visibility;
  
  import junit.framework.AssertionFailedError;
  import junit.framework.TestCase;
  
  import org.junit.Test;
  
  import java.io.IOException;
  import java.io.Serializable;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.TreeMap;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  /**
   * Automatically runs sanity checks against top level classes in the same package of the test that
   * extends {@code AbstractPackageSanityTests}. Currently sanity checks include {@link
   * NullPointerTester}, {@link EqualsTester} and {@link SerializableTester}. For example: <pre>
   * public class PackageSanityTests extends AbstractPackageSanityTests {}
   * </pre>
   *
   * <p>Note that only top-level classes with either a non-private constructor or a non-private static
   * factory method to construct instances can have their instance methods checked. For example: <pre>
   * public class Address {
   *   private final String city;
   *   private final String state;
   *   private final String zipcode;
   *
   *   public Address(String city, String state, String zipcode) {...}
   *
   *   {@literal @Override} public boolean equals(Object obj) {...}
   *   {@literal @Override} public int hashCode() {...}
   *   ...
   * }
   * </pre>
   * <p>No cascading checks are performed against the return values of methods unless the method is a
   * static factory method. Neither are semantics of mutation methods such as {@code
   * someList.add(obj)} checked. For more detailed discussion of supported and unsupported cases, see
   * {@link #testEquals}, {@link #testNulls} and {@link #testSerializable}.
   *
   * <p>For testing against the returned instances from a static factory class, such as <pre>
   * interface Book {...}
   * public class Books {
   *   public static Book hardcover(String title) {...}
   *   public static Book paperback(String title) {...}
   * }
   * </pre>
   *
   * <p>please use {@link ClassSanityTester#forAllPublicStaticMethods}.
   *
   * <p>If not all classes on the classpath should be covered, {@link
   * #ignoreClasses} can be used to exclude certain classes.
   *
   * <p>{@link #setDefault} allows subclasses to specify default values for types.
   *
   * <p>This class incurs IO because it scans the classpath and reads classpath resources.
   *
   * @author Ben Yu
   * @since 14.0
   */
  @Beta
  // TODO: Switch to JUnit 4 and use @Parameterized and @BeforeClass
  public abstract class AbstractPackageSanityTests extends TestCase {
  
   /* The names of the expected method that tests null checks. */
   private static final ImmutableList<String> NULL_TEST_METHOD_NAMES = ImmutableList.of(
       "testNulls", "testNull",
       "testNullPointers", "testNullPointer",
       "testNullPointerExceptions", "testNullPointerException");
 
   /* The names of the expected method that tests serializable. */
   private static final ImmutableList<String> SERIALIZABLE_TEST_METHOD_NAMES = ImmutableList.of(
       "testSerializable", "testSerialization",
       "testEqualsAndSerializable", "testEqualsAndSerialization");
 
   /* The names of the expected method that tests equals. */
   private static final ImmutableList<String> EQUALS_TEST_METHOD_NAMES = ImmutableList.of(
       "testEquals", "testEqualsAndHashCode",
       "testEqualsAndSerializable", "testEqualsAndSerialization",
       "testEquality");
 
   private static final Chopper TEST_SUFFIX =
       suffix("Test")
           .or(suffix("Tests"))
           .or(suffix("TestCase"))
           .or(suffix("TestSuite"));
 
   private final Logger logger = Logger.getLogger(getClass().getName());
   private final ClassSanityTester tester = new ClassSanityTester();
   private Visibility visibility = Visibility.PACKAGE;
   private Predicate<Class<?>> classFilter = new Predicate<Class<?>>() {
     @Override public boolean apply(Class<?> cls) {
       return visibility.isVisible(cls.getModifiers());
     }
   };
 
   /**
    * Restricts the sanity tests for public API only. By default, package-private API are also
    * covered.
    */
   protected final void publicApiOnly() {
     visibility = Visibility.PUBLIC;
   }
 
   /**
    * Tests all top-level {@link Serializable} classes in the package. For a serializable Class
    * {@code C}:
    * <ul>
    * <li>If {@code C} explicitly implements {@link Object#equals}, the deserialized instance will be
    *     checked to be equal to the instance before serialization.
    * <li>If {@code C} doesn't explicitly implement {@code equals} but instead inherits it from a
    *     superclass, no equality check is done on the deserialized instance because it's not clear
    *     whether the author intended for the class to be a value type.
    * <li>If a constructor or factory method takes a parameter whose type is interface, a dynamic
    *     proxy will be passed to the method. It's possible that the method body expects an instance
    *     method of the passed-in proxy to be of a certain value yet the proxy isn't aware of the
    *     assumption, in which case the equality check before and after serialization will fail.
    * <li>If the constructor or factory method takes a parameter that {@link
    *     AbstractPackageSanityTests} doesn't know how to construct, the test will fail.
    * <li>If there is no visible constructor or visible static factory method declared by {@code C},
    *     {@code C} is skipped for serialization test, even if it implements {@link Serializable}.
    * <li>Serialization test is not performed on method return values unless the method is a visible
    *     static factory method whose return type is {@code C} or {@code C}'s subtype.
    * </ul>
    *
    * <p>In all cases, if {@code C} needs custom logic for testing serialization, you can add an
    * explicit {@code testSerializable()} test in the corresponding {@code CTest} class, and {@code
    * C} will be excluded from automated serialization test performed by this method.
    */
   @Test
   public void testSerializable() throws Exception {
     // TODO: when we use @BeforeClass, we can pay the cost of class path scanning only once.
     for (Class<?> classToTest
         : findClassesToTest(loadClassesInPackage(), SERIALIZABLE_TEST_METHOD_NAMES)) {
       if (Serializable.class.isAssignableFrom(classToTest)) {
         try {
           Object instance = tester.instantiate(classToTest);
           if (instance != null) {
             if (isEqualsDefined(classToTest)) {
               SerializableTester.reserializeAndAssert(instance);
             } else {
               SerializableTester.reserialize(instance);
             }
           }
         } catch (Throwable e) {
           throw sanityError(classToTest, SERIALIZABLE_TEST_METHOD_NAMES, "serializable test", e);
         }
       }
     }
   }
 
   /**
    * Performs {@link NullPointerTester} checks for all top-level classes in the package. For a class
    * {@code C}
    * <ul>
    * <li>All visible static methods are checked such that passing null for any parameter that's not
    *     annotated with {@link javax.annotation.Nullable} should throw {@link NullPointerException}.
    * <li>If there is any visible constructor or visible static factory method declared by the class,
    *     all visible instance methods will be checked too using the instance created by invoking the
    *     constructor or static factory method.
    * <li>If the constructor or factory method used to construct instance takes a parameter that
    *     {@link AbstractPackageSanityTests} doesn't know how to construct, the test will fail.
    * <li>If there is no visible constructor or visible static factory method declared by {@code C},
    *     instance methods are skipped for nulls test.
    * <li>Nulls test is not performed on method return values unless the method is a visible static
    *     factory method whose return type is {@code C} or {@code C}'s subtype.
    * </ul>
    *
    * <p>In all cases, if {@code C} needs custom logic for testing nulls, you can add an explicit
    * {@code testNulls()} test in the corresponding {@code CTest} class, and {@code C} will be
    * excluded from the automated null tests performed by this method.
    */
   @Test
   public void testNulls() throws Exception {
     for (Class<?> classToTest
         : findClassesToTest(loadClassesInPackage(), NULL_TEST_METHOD_NAMES)) {
       try {
         tester.doTestNulls(classToTest, visibility);
       } catch (Throwable e) {
         throw sanityError(classToTest, NULL_TEST_METHOD_NAMES, "nulls test", e);
       }
     }
   }
 
   /**
    * Tests {@code equals()} and {@code hashCode()} implementations for every top-level class in the
    * package, that explicitly implements {@link Object#equals}. For a class {@code C}:
    * <ul>
    * <li>The visible constructor or visible static factory method with the most parameters is used
    *     to construct the sample instances. In case of tie, the candidate constructors or factories
    *     are tried one after another until one can be used to construct sample instances.
    * <li>For the constructor or static factory method used to construct instances, it's checked that
    *     when equal parameters are passed, the result instance should also be equal; and vice versa.
    * <li>Inequality check is not performed against state mutation methods such as {@link List#add},
    *     or functional update methods such as {@link com.google.common.base.Joiner#skipNulls}.
    * <li>If the constructor or factory method used to construct instance takes a parameter that
    *     {@link AbstractPackageSanityTests} doesn't know how to construct, the test will fail.
    * <li>If there is no visible constructor or visible static factory method declared by {@code C},
    *     {@code C} is skipped for equality test.
    * <li>Equality test is not performed on method return values unless the method is a visible
    *     static factory method whose return type is {@code C} or {@code C}'s subtype.
    * </ul>
    *
    * <p>In all cases, if {@code C} needs custom logic for testing {@code equals()}, you can add an
    * explicit {@code testEquals()} test in the corresponding {@code CTest} class, and {@code C} will
    * be excluded from the automated {@code equals} test performed by this method.
    */
   @Test
   public void testEquals() throws Exception {
     for (Class<?> classToTest
         : findClassesToTest(loadClassesInPackage(), EQUALS_TEST_METHOD_NAMES)) {
       if (!classToTest.isEnum() && isEqualsDefined(classToTest)) {
         try {
           tester.doTestEquals(classToTest);
         } catch (Throwable e) {
           throw sanityError(classToTest, EQUALS_TEST_METHOD_NAMES, "equals test", e);
         }
       }
     }
   }
 
   /**
    * Sets the default value for {@code type}, when dummy value for a parameter of the same type
    * needs to be created in order to invoke a method or constructor. The default value isn't used in
    * testing {@link Object#equals} because more than one sample instances are needed for testing
    * inequality.
    */
   protected final <T> void setDefault(Class<T> type, T value) {
     tester.setDefault(type, value);
   }
 
   /**
    * Sets two distinct values for {@code type}. These values can be used for both null pointer
    * testing and equals testing.
    *
    * @since 17.0
    */
   protected final <T> void setDistinctValues(Class<T> type, T value1, T value2) {
     tester.setDistinctValues(type, value1, value2);
   }
 
   /** Specifies that classes that satisfy the given predicate aren't tested for sanity. */
   protected final void ignoreClasses(Predicate<? super Class<?>> condition) {
     this.classFilter = and(this.classFilter, not(condition));
   }
 
   private static AssertionFailedError sanityError(
       Class<?> cls, List<String> explicitTestNames, String description, Throwable e) {
     String message = String.format(
         "Error in automated %s of %s\n"
             + "If the class is better tested explicitly, you can add %s() to %sTest",
         description, cls, explicitTestNames.get(0), cls.getName());
     AssertionFailedError error = new AssertionFailedError(message);
     error.initCause(e);
     return error;
   }
 
   /**
    * Finds the classes not ending with a test suffix and not covered by an explicit test
    * whose name is {@code explicitTestName}.
    */
   @VisibleForTesting List<Class<?>> findClassesToTest(
       Iterable<? extends Class<?>> classes, Iterable<String> explicitTestNames) {
     // "a.b.Foo" -> a.b.Foo.class
     TreeMap<String, Class<?>> classMap = Maps.newTreeMap();
     for (Class<?> cls : classes) {
       classMap.put(cls.getName(), cls);
     }
     // Foo.class -> [FooTest.class, FooTests.class, FooTestSuite.class, ...]
     Multimap<Class<?>, Class<?>> testClasses = HashMultimap.create();
     LinkedHashSet<Class<?>> candidateClasses = Sets.newLinkedHashSet();
     for (Class<?> cls : classes) {
       Optional<String> testedClassName = TEST_SUFFIX.chop(cls.getName());
       if (testedClassName.isPresent()) {
         Class<?> testedClass = classMap.get(testedClassName.get());
         if (testedClass != null) {
           testClasses.put(testedClass, cls);
         }
       } else {
         candidateClasses.add(cls);
       }
     }
     List<Class<?>> result = Lists.newArrayList();
     NEXT_CANDIDATE: for (Class<?> candidate : Iterables.filter(candidateClasses, classFilter)) {
       for (Class<?> testClass : testClasses.get(candidate)) {
         if (hasTest(testClass, explicitTestNames)) {
           // covered by explicit test
           continue NEXT_CANDIDATE;
         }
       }
       result.add(candidate);
     }
     return result;
   }
 
   private List<Class<?>> loadClassesInPackage() throws IOException {
     List<Class<?>> classes = Lists.newArrayList();
     String packageName = getClass().getPackage().getName();
     for (ClassPath.ClassInfo classInfo 
         : ClassPath.from(getClass().getClassLoader()).getTopLevelClasses(packageName)) {
       Class<?> cls;
       try {
         cls = classInfo.load();
       } catch (NoClassDefFoundError e) {
         // In case there were linking problems, this is probably not a class we care to test anyway.
         logger.log(Level.SEVERE, "Cannot load class " + classInfo + ", skipping...", e);
         continue;
       }
       if (!cls.isInterface()) {
         classes.add(cls);
       }
     }
     return classes;
   }
 
   private static boolean hasTest(Class<?> testClass, Iterable<String> testNames) {
     for (String testName : testNames) {
       try {
         testClass.getMethod(testName);
         return true;
       } catch (NoSuchMethodException e) {
         continue;
       }
     }
     return false;
   }
 
   private static boolean isEqualsDefined(Class<?> cls) {
     try {
       return !cls.getDeclaredMethod("equals", Object.class).isSynthetic();
     } catch (NoSuchMethodException e) {
       return false;
     }
   }
 
   static abstract class Chopper {
 
     final Chopper or(final Chopper you) {
       final Chopper i = this;
       return new Chopper() {
         @Override Optional<String> chop(String str) {
           return i.chop(str).or(you.chop(str));
         }
       };
     }
 
     abstract Optional<String> chop(String str);
 
     static Chopper suffix(final String suffix) {
       return new Chopper() {
         @Override Optional<String> chop(String str) {
           if (str.endsWith(suffix)) {
             return Optional.of(str.substring(0, str.length() - suffix.length()));
           } else {
             return Optional.absent();
           }
         }
       };
     }
   }
 }