Asserts.java

/**
 * Copyright (C) 2008 Google Inc.
 *
 * 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.inject;

import static com.google.inject.internal.InternalFlags.IncludeStackTraceOption;
import static com.google.inject.internal.InternalFlags.getIncludeStackTraceOption;
import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertNotNull;
import static junit.framework.Assert.assertTrue;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;

import junit.framework.Assert;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * @author jessewilson@google.com (Jesse Wilson)
 */
public class Asserts {
  private Asserts() {}

  /**
   * Returns the String that would appear in an error message for this chain of classes 
   * as modules.
   */
  public static String asModuleChain(Class... classes) {
    return Joiner.on(" -> ").appendTo(new StringBuilder(" (via modules: "),
        Iterables.transform(ImmutableList.copyOf(classes), new Function<Class, String>() {
          @Override
          public String apply(Class input) {
            return input.getName();
          }
        })).append(")").toString();
  }

  /**
   * Returns the source file appears in error messages based on {@link 
   * #getIncludeStackTraceOption()} value.
   */
  public static String getDeclaringSourcePart(Class clazz) {
    if (getIncludeStackTraceOption() == IncludeStackTraceOption.OFF) {
      return ".configure(Unknown Source";
    }
    return ".configure(" + clazz.getSimpleName() + ".java:";
  }

  /**
   * Returns true if {@link #getIncludeStackTraceOption()} returns {@link
   * IncludeStackTraceOption#OFF}.
   */
  public static boolean isIncludeStackTraceOff() {
    return getIncludeStackTraceOption() == IncludeStackTraceOption.OFF;
  }

  /**
   * Returns true if {@link #getIncludeStackTraceOption()} returns {@link
   * IncludeStackTraceOption#COMPLETE}.
   */
  public static boolean isIncludeStackTraceComplete() {
    return getIncludeStackTraceOption() == IncludeStackTraceOption.COMPLETE;
  }

  /**
   * Fails unless {@code expected.equals(actual)}, {@code
   * actual.equals(expected)} and their hash codes are equal. This is useful
   * for testing the equals method itself.
   */
  public static void assertEqualsBothWays(Object expected, Object actual) {
    assertNotNull(expected);
    assertNotNull(actual);
    assertEquals("expected.equals(actual)", actual, expected);
    assertEquals("actual.equals(expected)", expected, actual);
    assertEquals("hashCode", expected.hashCode(), actual.hashCode());
  }

  /**
   * Fails unless {@code text} includes all {@code substrings}, in order.
   */
  public static void assertContains(String text, String... substrings) {
    /*if[NO_AOP]
    // when we strip out bytecode manipulation, we lose the ability to generate some source lines.
    if (text.contains("(Unknown Source)")) {
      return;
    }
    end[NO_AOP]*/

    int startingFrom = 0;
    for (String substring : substrings) {
      int index = text.indexOf(substring, startingFrom);
      assertTrue(String.format("Expected \"%s\" to contain substring \"%s\"", text, substring),
          index >= startingFrom);
      startingFrom = index + substring.length();
    }

    String lastSubstring = substrings[substrings.length - 1];
    assertTrue(String.format("Expected \"%s\" to contain substring \"%s\" only once),",
        text, lastSubstring), text.indexOf(lastSubstring, startingFrom) == -1);
  }

  /**
   * Fails unless {@code object} doesn't equal itself when reserialized.
   */
  public static void assertEqualWhenReserialized(Object object)
      throws IOException {
    Object reserialized = reserialize(object);
    assertEquals(object, reserialized);
    assertEquals(object.hashCode(), reserialized.hashCode());
  }

  /**
   * Fails unless {@code object} has the same toString value when reserialized.
   */
  public static void assertSimilarWhenReserialized(Object object) throws IOException {
    Object reserialized = reserialize(object);
    assertEquals(object.toString(), reserialized.toString());
  }

  public static <E> E reserialize(E original) throws IOException {
    try {
      ByteArrayOutputStream out = new ByteArrayOutputStream();
      new ObjectOutputStream(out).writeObject(original);
      ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
      @SuppressWarnings("unchecked") // the reserialized type is assignable
      E reserialized = (E) new ObjectInputStream(in).readObject();
      return reserialized;
    } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
    }
  }

  public static void assertNotSerializable(Object object) throws IOException {
    try {
      reserialize(object);
      Assert.fail();
    } catch (NotSerializableException expected) {
    }
  }
}