common/io/CloseablesTest.java

/*
 * Copyright (C) 2007 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 org.easymock.EasyMock.createStrictMock;
import static org.easymock.EasyMock.expectLastCall;
import static org.easymock.EasyMock.replay;
import static org.easymock.EasyMock.reset;
import static org.easymock.EasyMock.verify;

import junit.framework.TestCase;

import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;

/**
 * Unit tests for {@link Closeables} and {@link Flushables}.
 *
 * <p>Checks proper closing and flushing behavior, and ensures that
 * IOExceptions on Closeable.close() or Flushable.flush() are not
 * propagated out from the {@link Closeables#close} method if {@code
 * swallowException} is true.
 *
 * @author Michael Lancaster
 */
public class CloseablesTest extends TestCase {
  private Closeable mockCloseable;
  private Flushable mockFlushable;

  public void testClose_closeableClean() throws IOException {
    // make sure that no exception is thrown regardless of value of
    // 'swallowException' when the mock does not throw an exception.
    setupCloseable(false);
    doClose(mockCloseable, false, false);

    setupCloseable(false);
    doClose(mockCloseable, true, false);
  }

  public void testClose_closeableWithEatenException() throws IOException {
    // make sure that no exception is thrown if 'swallowException' is true
    // when the mock does throw an exception.
    setupCloseable(true);
    doClose(mockCloseable, true);
  }

  public void testClose_closeableWithThrownException() throws IOException {
    // make sure that the exception is thrown if 'swallowException' is false
    // when the mock does throw an exception.
    setupCloseable(true);
    doClose(mockCloseable, false);
  }

  public void testCloseQuietly_closeableWithEatenException()
      throws IOException {
    // make sure that no exception is thrown by CloseQuietly when the mock does
    // throw an exception, either on close, on flush, or both.
    setupCloseable(true);
    Closeables.closeQuietly(mockCloseable);
  }

  public void testFlush_clean() throws IOException {
    // make sure that no exception is thrown regardless of value of
    // 'swallowException' when the mock does not throw an exception.
    setupFlushable(false);
    doFlush(mockFlushable, false, false);

    setupFlushable(false);
    doFlush(mockFlushable, true, false);
  }

  public void testFlush_flushableWithEatenException() throws IOException {
    // make sure that no exception is thrown if 'swallowException' is true
    // when the mock does throw an exception on flush.
    setupFlushable(true);
    doFlush(mockFlushable, true, false);
  }

  public void testFlush_flushableWithThrownException() throws IOException {
    // make sure that the exception is thrown if 'swallowException' is false
    // when the mock does throw an exception on flush.
    setupFlushable(true);
    doFlush(mockFlushable, false, true);
  }

  public void testFlushQuietly_flushableWithEatenException()
      throws IOException {
    // make sure that no exception is thrown by CloseQuietly when the mock does
    // throw an exception on flush.
    setupFlushable(true);
    Flushables.flushQuietly(mockFlushable);
  }

  public void testCloseNull() throws IOException {
    Closeables.close(null, true);
    Closeables.close(null, false);
    Closeables.closeQuietly(null);
  }

  @Override protected void setUp() throws Exception {
    mockCloseable = createStrictMock(Closeable.class);
    mockFlushable = createStrictMock(Flushable.class);
  }

  private void expectThrown() {
    expectLastCall().andThrow(new IOException("This should only appear in the "
        + "logs. It should not be rethrown."));
  }

  // Set up a closeable to expect to be closed, and optionally to throw an
  // exception.
  private void setupCloseable(boolean shouldThrow) throws IOException {
    reset(mockCloseable);
    mockCloseable.close();
    if (shouldThrow) {
      expectThrown();
    }
    replay(mockCloseable);
  }

  // Set up a flushable to expect to be flushed and closed, and optionally to
  // throw an exception.
  private void setupFlushable(boolean shouldThrowOnFlush) throws IOException {
    reset(mockFlushable);
    mockFlushable.flush();
    if (shouldThrowOnFlush) {
      expectThrown();
    }
    replay(mockFlushable);
  }

  private void doClose(Closeable closeable, boolean swallowException) {
    doClose(closeable, swallowException, !swallowException);
  }

  // Close the closeable using the Closeables, passing in the swallowException
  // parameter. expectThrown determines whether we expect an exception to
  // be thrown by Closeables.close;
  private void doClose(Closeable closeable, boolean swallowException,
      boolean expectThrown) {
    try {
      Closeables.close(closeable, swallowException);
      if (expectThrown) {
        fail("Didn't throw exception.");
      }
    } catch (IOException e) {
      if (!expectThrown) {
        fail("Threw exception");
      }
    }
    verify(closeable);
  }

  // Flush the flushable using the Flushables, passing in the swallowException
  // parameter. expectThrown determines whether we expect an exception to
  // be thrown by Flushables.flush;
  private void doFlush(Flushable flushable, boolean swallowException,
      boolean expectThrown) {
    try {
      Flushables.flush(flushable, swallowException);
      if (expectThrown) {
        fail("Didn't throw exception.");
      }
    } catch (IOException e) {
      if (!expectThrown) {
        fail("Threw exception");
      }
    }
    verify(flushable);
  }
}