/*
 * Copyright 2014 Google Inc. All Rights Reserved.
 *
 * 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.errorprone.bugpatterns;

import static com.google.errorprone.BugPattern.Category.JUNIT;
import static com.google.errorprone.BugPattern.MaturityLevel.MATURE;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.JUnitMatchers.hasJUnit4TestCases;
import static com.google.errorprone.matchers.JUnitMatchers.isTestCaseDescendant;
import static com.google.errorprone.matchers.Matchers.allOf;

import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;

import com.sun.source.tree.ClassTree;

/**
 * @author mwacker@google.com (Mike Wacker)
 */
@BugPattern(
    name = "JUnitAmbiguousTestClass",
    summary = "Test class mixes JUnit 3 and JUnit 4 idioms",
    explanation = "The test class could execute either as a JUnit 3 class or a JUnit 4 class, "
        + "and tests could behave differently depending on whether it runs in JUnit 3 or JUnit 4. "
        + "In particular, as a JUnit 4 class, it may not work as intended.",
    category = JUNIT, maturity = MATURE, severity = WARNING)
public class JUnitAmbiguousTestClass extends BugChecker implements ClassTreeMatcher {

  private static final Matcher<ClassTree> matcher = allOf(
      isTestCaseDescendant,
      hasJUnit4TestCases);

  @Override
  public Description matchClass(ClassTree classTree, VisitorState state) {
    return matcher.matches(classTree, state) ? describeMatch(classTree) : NO_MATCH;
  }
}

@@ -1570,216 +1570,416 @@
 ass 
-mixes JUnit 3 and JUnit 4 idioms%22,%0A    explanation = %22The test class could execute either as a JUnit 3 class or a JUnit 4 class, %22%0A        + %22and tests could behave differently depending on whether it
+inherits from JUnit 3's TestCase but has JUnit 4 @Test annotations.%22,%0A    explanation = %22JUnit 3 uses inheritance, whereas JUnit 4 uses composition. %22%0A        + %22Mixing these two design patterns historically has been a source of test bugs and %22%0A        + %22unexpected behavior (e.g.: teardown logic and/or verification does not run). %22%0A        + %22Error Prone also cannot infer whether the test class
  runs 
-in
+with
  JUn
@@ -2012,71 +2012,315 @@
  + %22
-In particular, as a JUnit 4 class, it may not work as intended.
+Thus, even if the test class runs with JUnit 4, Error Prone will not run %22%0A        + %22additional checks which can catch common errors with JUnit 4 test classes. %22%0A        + %22Either use only JUnit 4 and remove the inheritance from TestCase, %22%0A        + %22or use only JUnit 3 and remove the @Test annotations. 
 %22,%0A 

Improve documentation for JUnitAmbiguousTestClass