/*
 * Copyright 2020 The Error Prone 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.errorprone.bugpatterns;

import com.google.errorprone.CompilationTestHelper;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** {@link ReturnsNullCollection}Test */
@RunWith(JUnit4.class)
public class ReturnsNullCollectionTest {

  private final CompilationTestHelper compilationHelper =
      CompilationTestHelper.newInstance(ReturnsNullCollection.class, getClass());

  @Test
  public void positive() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import com.google.common.collect.Multimap;
            import com.google.common.collect.Table;
            import java.util.Collection;
            import java.util.ArrayList;
            import java.util.List;
            import java.util.Map;

            class Test {
              Collection<String> methodReturnsNullCollection() {
                // BUG: Diagnostic contains: ReturnsNullCollection
                return null;
              }

              List<String> methodReturnsNullList() {
                // BUG: Diagnostic contains: ReturnsNullCollection
                return null;
              }

              Map<String, String> methodReturnsNullMap() {
                // BUG: Diagnostic contains: ReturnsNullCollection
                return null;
              }

              Multimap<String, String> methodReturnsNullMultimap() {
                // BUG: Diagnostic contains: ReturnsNullCollection
                return null;
              }

              Table<String, String, String> methodReturnsNullTable() {
                // BUG: Diagnostic contains: ReturnsNullCollection
                return null;
              }

              List<String> methodReturnsNullListConditionally(boolean foo) {
                if (foo) {
                  // BUG: Diagnostic contains: ReturnsNullCollection
                  return null;
                }
                return new ArrayList();
              }
            }
            """)
        .doTest();
  }

  @Test
  public void negative() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import java.util.Collection;
            import java.util.HashMap;
            import java.util.List;
            import java.util.Map;
            import javax.annotation.Nullable;

            class Test {
              @Nullable
              Collection<String> methodReturnsNullCollection() {
                return null;
              }

              @Nullable
              List<String> methodReturnsNullList() {
                return null;
              }

              @Nullable
              Map<String, String> methodReturnsNullMap() {
                return null;
              }

              @Nullable
              HashMap<String, String> methodReturnsNullHashMap() {
                return null;
              }
            }
            """)
        .doTest();
  }
}
