android13/external/dagger2/javatests/dagger/functional/nullables/NullabilityTest.java

/*
 * Copyright (C) 2015 The Dagger 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 dagger.functional.nullables;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import javax.inject.Provider;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class NullabilityTest {
  @Test public void testNullability_provides() {
    NullModule module = new NullModule();
    NullComponent component = DaggerNullComponent.builder().nullModule(module).build();

    // Can't construct NullFoo because it depends on Number, and Number was null.
    try {
      component.nullFoo();
      fail();
    } catch (NullPointerException npe) {
      assertThat(npe)
          .hasMessageThat()
          .isEqualTo("Cannot return null from a non-@Nullable @Provides method");
    }

    // set number to non-null so we can create
    module.numberValue = 1;
    NullFoo nullFoo = component.nullFoo();

    // Then set it back to null so we can test its providers.
    module.numberValue = null;
    validate(true, nullFoo.string, nullFoo.stringProvider, nullFoo.numberProvider);
    validate(true, nullFoo.methodInjectedString, nullFoo.methodInjectedStringProvider,
        nullFoo.methodInjectedNumberProvider);
    validate(true, nullFoo.fieldInjectedString, nullFoo.fieldInjectedStringProvider,
        nullFoo.fieldInjectedNumberProvider);
  }

  @Test public void testNullability_reusuable() {
    NullModule module = new NullModule();
    NullComponent component = DaggerNullComponent.builder().nullModule(module).build();

    // Test that the @Nullable @Reusuable binding is cached properly even when the value is null.
    assertThat(module.integerCallCount).isEqualTo(0);
    assertThat(component.integer()).isNull();
    assertThat(module.integerCallCount).isEqualTo(1);
    assertThat(component.integer()).isNull();
    assertThat(module.integerCallCount).isEqualTo(1);
  }

  @Test public void testNullability_components() {
    NullComponent nullComponent = new NullComponent() {
      @Override public Provider<String> stringProvider() {
        return new Provider<String>() {
          @Override public String get() {
            return null;
          }
        };
      }

      @Override public String string() {
        return null;
      }

      @Override public Provider<Number> numberProvider() {
        return new Provider<Number>() {
          @Override public Number get() {
            return null;
          }
        };
      }

      @Override public Number number() {
        return null;
      }

      @Override public NullFoo nullFoo() {
        return null;
      }

      @Override public Integer integer() {
        return null;
      }
    };
    NullComponentWithDependency component =
        DaggerNullComponentWithDependency.builder().nullComponent(nullComponent).build();
    validate(false, component.string(), component.stringProvider(), component.numberProvider());

    // Also validate that the component's number() method fails
    try {
      component.number();
      fail();
    } catch (NullPointerException npe) {
      assertThat(npe)
          .hasMessageThat()
          .isEqualTo("Cannot return null from a non-@Nullable component method");
    }
  }

  private void validate(boolean fromProvides,
      String string,
      Provider<String> stringProvider,
      Provider<Number> numberProvider) {
    assertThat(string).isNull();
    assertThat(numberProvider).isNotNull();
    try {
      numberProvider.get();
      fail();
    } catch (NullPointerException npe) {
      assertThat(npe)
          .hasMessageThat()
          .isEqualTo(
              "Cannot return null from a non-@Nullable "
                  + (fromProvides ? "@Provides" : "component")
                  + " method");
    }
    assertThat(stringProvider.get()).isNull();
  }
}