Java example source code file (CloserTest.java)

This example Java source code file (CloserTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

annotation, assertionerror, closer, error, ioexception, log, logging, look, override, reflection, runtimeexception, string, suppressing, suppression, testcloseable, testloghandler, testsuppressor, throwable, util

The CloserTest.java Java example source code

/*
 * Copyright (C) 2012 The Guava 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.common.io;

import static com.google.common.truth.Truth.assertThat;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.base.Splitter;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.testing.TestLogHandler;

import junit.framework.TestCase;

import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.logging.LogRecord;

import javax.annotation.Nullable;

/**
 * Tests for {@link Closer}.
 *
 * @author Colin Decker
 */
public class CloserTest extends TestCase {

  private TestSuppressor suppressor;

  @Override
  protected void setUp() throws Exception {
    suppressor = new TestSuppressor();
  }

  @AndroidIncompatible // TODO(cpovirk): Look up Build.VERSION.SDK_INT reflectively.
  public void testCreate() {
    Closer closer = Closer.create();
    String javaVersion = System.getProperty("java.version");
    String secondPart = Iterables.get(Splitter.on('.').split(javaVersion), 1);
    int versionNumber = Integer.parseInt(secondPart);
    if (versionNumber < 7) {
      assertThat(closer.suppressor).isInstanceOf(Closer.LoggingSuppressor.class);
    } else {
      assertThat(closer.suppressor).isInstanceOf(Closer.SuppressingSuppressor.class);
    }
  }

  public void testNoExceptionsThrown() throws IOException {
    Closer closer = new Closer(suppressor);

    TestCloseable c1 = closer.register(TestCloseable.normal());
    TestCloseable c2 = closer.register(TestCloseable.normal());
    TestCloseable c3 = closer.register(TestCloseable.normal());

    assertFalse(c1.isClosed());
    assertFalse(c2.isClosed());
    assertFalse(c3.isClosed());

    closer.close();

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertTrue(c3.isClosed());

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_fromTryBlock() throws IOException {
    Closer closer = new Closer(suppressor);

    TestCloseable c1 = closer.register(TestCloseable.normal());
    TestCloseable c2 = closer.register(TestCloseable.normal());

    IOException exception = new IOException();

    try {
      try {
        throw exception;
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    } catch (Throwable expected) {
      assertSame(exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whenCreatingCloseables() throws IOException {
    Closer closer = new Closer(suppressor);

    TestCloseable c1 = null;
    TestCloseable c2 = null;
    TestCloseable c3 = null;
    try {
      try {
        c1 = closer.register(TestCloseable.normal());
        c2 = closer.register(TestCloseable.normal());
        c3 = closer.register(TestCloseable.throwsOnCreate());
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    } catch (Throwable expected) {
      assertThat(expected).isInstanceOf(IOException.class);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertNull(c3);

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whileClosingLastCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

    IOException exception = new IOException();

    // c1 is added first, closed last
    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(exception));
    TestCloseable c2 = closer.register(TestCloseable.normal());

    try {
      closer.close();
    } catch (Throwable expected) {
      assertSame(exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testExceptionThrown_whileClosingFirstCloseable() throws IOException {
    Closer closer = new Closer(suppressor);

    IOException exception = new IOException();

    // c2 is added last, closed first
    TestCloseable c1 = closer.register(TestCloseable.normal());
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(exception));

    try {
      closer.close();
    } catch (Throwable expected) {
      assertSame(exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testCloseExceptionsSuppressed_whenExceptionThrownFromTryBlock() throws IOException {
    Closer closer = new Closer(suppressor);

    IOException tryException = new IOException();
    IOException c1Exception = new IOException();
    IOException c2Exception = new IOException();

    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(c1Exception));
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(c2Exception));

    try {
      try {
        throw tryException;
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    } catch (Throwable expected) {
      assertSame(tryException, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertSuppressed(
        new Suppression(c2, tryException, c2Exception),
        new Suppression(c1, tryException, c1Exception));
  }

  public void testCloseExceptionsSuppressed_whenExceptionThrownClosingFirstCloseable()
      throws IOException {
    Closer closer = new Closer(suppressor);

    IOException c1Exception = new IOException();
    IOException c2Exception = new IOException();
    IOException c3Exception = new IOException();

    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(c1Exception));
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(c2Exception));
    TestCloseable c3 = closer.register(TestCloseable.throwsOnClose(c3Exception));

    try {
      closer.close();
    } catch (Throwable expected) {
      assertSame(c3Exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertTrue(c3.isClosed());

    assertSuppressed(
        new Suppression(c2, c3Exception, c2Exception),
        new Suppression(c1, c3Exception, c1Exception));
  }

  public void testRuntimeExceptions() throws IOException {
    Closer closer = new Closer(suppressor);

    RuntimeException tryException = new RuntimeException();
    RuntimeException c1Exception = new RuntimeException();
    RuntimeException c2Exception = new RuntimeException();

    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(c1Exception));
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(c2Exception));

    try {
      try {
        throw tryException;
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    } catch (Throwable expected) {
      assertSame(tryException, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertSuppressed(
        new Suppression(c2, tryException, c2Exception),
        new Suppression(c1, tryException, c1Exception));
  }

  public void testErrors() throws IOException {
    Closer closer = new Closer(suppressor);

    Error c1Exception = new Error();
    Error c2Exception = new Error();
    Error c3Exception = new Error();

    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(c1Exception));
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(c2Exception));
    TestCloseable c3 = closer.register(TestCloseable.throwsOnClose(c3Exception));

    try {
      closer.close();
    } catch (Throwable expected) {
      assertSame(c3Exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());
    assertTrue(c3.isClosed());

    assertSuppressed(
        new Suppression(c2, c3Exception, c2Exception),
        new Suppression(c1, c3Exception, c1Exception));
  }

  public static void testLoggingSuppressor() throws IOException {
    TestLogHandler logHandler = new TestLogHandler();

    Closeables.logger.addHandler(logHandler);
    try {
      Closer closer = new Closer(new Closer.LoggingSuppressor());

      TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(new IOException()));
      TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(new RuntimeException()));
      try {
        throw closer.rethrow(new IOException("thrown"), IOException.class);
      } catch (IOException expected) {}

      assertTrue(logHandler.getStoredLogRecords().isEmpty());

      closer.close();

      assertEquals(2, logHandler.getStoredLogRecords().size());

      LogRecord record = logHandler.getStoredLogRecords().get(0);
      assertEquals("Suppressing exception thrown when closing " + c2, record.getMessage());

      record = logHandler.getStoredLogRecords().get(1);
      assertEquals("Suppressing exception thrown when closing " + c1, record.getMessage());
    } finally {
      Closeables.logger.removeHandler(logHandler);
    }
  }

  public static void testSuppressingSuppressorIfPossible() throws IOException {
    // can't test the JDK7 suppressor when not running on JDK7
    if (!Closer.SuppressingSuppressor.isAvailable()) {
      return;
    }

    Closer closer = new Closer(new Closer.SuppressingSuppressor());

    IOException thrownException = new IOException();
    IOException c1Exception = new IOException();
    RuntimeException c2Exception = new RuntimeException();

    TestCloseable c1 = closer.register(TestCloseable.throwsOnClose(c1Exception));
    TestCloseable c2 = closer.register(TestCloseable.throwsOnClose(c2Exception));
    try {
      try {
        throw thrownException;
      } catch (Throwable e) {
        throw closer.rethrow(thrownException, IOException.class);
      } finally {
        assertThat(getSuppressed(thrownException)).isEmpty();
        closer.close();
      }
    } catch (IOException expected) {
      assertSame(thrownException, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    ImmutableSet<Throwable> suppressed = ImmutableSet.copyOf(getSuppressed(thrownException));
    assertEquals(2, suppressed.size());

    assertEquals(ImmutableSet.of(c1Exception, c2Exception), suppressed);
  }

  public void testNullCloseable() throws IOException {
    Closer closer = Closer.create();
    closer.register(null);
    closer.close();
  }

  static Throwable[] getSuppressed(Throwable throwable) {
    try {
      Method getSuppressed = Throwable.class.getDeclaredMethod("getSuppressed");
      return (Throwable[]) getSuppressed.invoke(throwable);
    } catch (Exception e) {
      throw new AssertionError(e); // only called if running on JDK7
    }
  }

  /**
   * Asserts that an exception was thrown when trying to close each of the given throwables and that
   * each such exception was suppressed because of the given thrown exception.
   */
  private void assertSuppressed(Suppression... expected) {
    assertEquals(ImmutableList.copyOf(expected), suppressor.suppressions);
  }

  /**
   * Suppressor that records suppressions.
   */
  private static class TestSuppressor implements Closer.Suppressor {

    private final List<Suppression> suppressions = Lists.newArrayList();

    @Override
    public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
      suppressions.add(new Suppression(closeable, thrown, suppressed));
    }
  }

  /**
   * Record of a call to suppress.
   */
  private static class Suppression {
    private final Closeable closeable;
    private final Throwable thrown;
    private final Throwable suppressed;

    private Suppression(Closeable closeable, Throwable thrown, Throwable suppressed) {
      this.closeable = closeable;
      this.thrown = thrown;
      this.suppressed = suppressed;
    }

    @Override
    public boolean equals(Object obj) {
      if (obj instanceof Suppression) {
        Suppression other = (Suppression) obj;
        return closeable.equals(other.closeable)
            && thrown.equals(other.thrown)
            && suppressed.equals(other.suppressed);
      }
      return false;
    }

    @Override
    public int hashCode() {
      return Objects.hashCode(closeable, thrown, suppressed);
    }

    @Override
    public String toString() {
      return MoreObjects.toStringHelper(this)
          .add("closeable", closeable)
          .add("thrown", thrown)
          .add("suppressed", suppressed)
          .toString();
    }
  }

  private static class TestCloseable implements Closeable {

    private final Throwable throwOnClose;
    private boolean closed;

    static TestCloseable normal() throws IOException {
      return new TestCloseable(null);
    }

    static TestCloseable throwsOnClose(Throwable throwOnClose) throws IOException {
      return new TestCloseable(throwOnClose);
    }

    static TestCloseable throwsOnCreate() throws IOException {
      throw new IOException();
    }

    private TestCloseable(@Nullable Throwable throwOnClose) {
      this.throwOnClose = throwOnClose;
    }

    public boolean isClosed() {
      return closed;
    }

    @Override
    public void close() throws IOException {
      closed = true;
      if (throwOnClose != null) {
        Throwables.propagateIfPossible(throwOnClose, IOException.class);
        throw new AssertionError(throwOnClose);
      }
    }
  }
}