/*
 * Copyright 2016 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.inject.dagger;

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

/** Tests for {@link ProvidesNull}. */
@RunWith(JUnit4.class)
public class ProvidesNullTest {
  private final CompilationTestHelper compilationHelper =
      CompilationTestHelper.newInstance(ProvidesNull.class, getClass());

  // Positive cases

  @Test
  public void simple() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
import dagger.Provides;

public class Test {
  @Provides
  public Object providesObject() {
    // BUG: Diagnostic contains: Did you mean '@Nullable' or 'throw new RuntimeException();'
    return null;
  }
}
""")
        .doTest();
  }

  @Test
  public void hasJavaxAnnotationNullable() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;
            import javax.annotation.Nullable;

            public class Test {
              @Provides
              @Nullable
              public Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }

  @Test
  public void hasOtherNullable() {
    compilationHelper
        .addSourceLines("Nullable.java", "public @interface Nullable {}")
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;

            public class Test {
              @Provides
              @Nullable
              public Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }

  @Test
  public void hasTypeUseNullableOnMethod() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;
            import org.checkerframework.checker.nullness.qual.Nullable;

            public class Test {
              @Provides
              @Nullable
              public Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }

  @Test
  public void hasTypeUseNullableOnReturnType() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;
            import org.checkerframework.checker.nullness.qual.Nullable;

            public class Test {
              @Provides
              public @Nullable Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }

  /**
   * Tests that we do not flag Guice {@code @Provides} methods. While this is also wrong, there is
   * no enforcement in Guice and so the incorrect usage is too common to error on.
   */
  @Test
  public void guiceProvides() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import com.google.inject.Provides;

            public class Test {
              @Provides
              public Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }

  @Test
  public void inCatch() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
import java.io.IOException;
import dagger.Provides;

public class Test {
  @Provides
  public Object providesObject() {
    try {
      return new Object();
    } catch (Exception e) {
      // BUG: Diagnostic contains: Did you mean 'throw new RuntimeException(e);' or '@Nullable'
      return null;
    }
  }
}
""")
        .doTest();
  }

  @Test
  public void inTry() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
import dagger.Provides;

public class Test {
  @Provides
  public Object providesObject() {
    try {
      // BUG: Diagnostic contains: Did you mean '@Nullable' or 'throw new RuntimeException();'
      return null;
    } catch (Exception e) {
      return new Object();
    }
  }
}
""")
        .doTest();
  }

  @Test
  public void returnWithNoExpression() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;

            public class Test {
              public void doNothing() {
                return;
              }
            }
            """)
        .doTest();
  }

  @Test
  public void hasOtherTypeUseNullable() {
    compilationHelper
        .addSourceLines(
            "Nullable.java",
            """
            import static java.lang.annotation.ElementType.TYPE_USE;
            import java.lang.annotation.Target;

            @Target(TYPE_USE)
            public @interface Nullable {}
            """)
        .addSourceLines(
            "Test.java",
            """
            import dagger.Provides;

            public class Test {
              @Provides
              @Nullable
              public Object providesObject() {
                return null;
              }
            }
            """)
        .doTest();
  }
}
