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Better tests for FileChannels.contentEquals()
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‎src/test/java/org/apache/commons/io/channels/FileChannelsTest.java

+95-30
Original file line numberDiff line numberDiff line change
@@ -25,88 +25,153 @@
2525
import java.io.FileInputStream;
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import java.io.IOException;
2727
import java.nio.channels.FileChannel;
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import java.nio.file.Files;
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import java.nio.file.Path;
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2931
import org.apache.commons.io.FileUtils;
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import org.apache.commons.io.IOUtils;
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import org.apache.commons.io.file.AbstractTempDirTest;
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import org.apache.commons.lang3.ArrayUtils;
3135
import org.apache.commons.lang3.StringUtils;
32-
import org.junit.jupiter.api.Test;
36+
import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.MethodSource;
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/**
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* Tests {@link FileChannels}.
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*/
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public class FileChannelsTest extends AbstractTempDirTest {
3843

39-
private static final int BUFFER_SIZE = 1024;
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private static final String CONTENT = StringUtils.repeat("x", BUFFER_SIZE);
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private static final int SMALL_BUFFER_SIZE = 1024;
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private static final String CONTENT = StringUtils.repeat("x", SMALL_BUFFER_SIZE);
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47+
public static int[] getBufferSizes() {
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// 1 and 2 are unusual and slow edge cases, but edge cases nonetheless.
49+
return new int[] { 1, 2, IOUtils.DEFAULT_BUFFER_SIZE / 10, IOUtils.DEFAULT_BUFFER_SIZE, IOUtils.DEFAULT_BUFFER_SIZE * 10 };
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}
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52+
private static byte reverse(final byte b) {
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return (byte) (~b & 0xff);
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}
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4256
private boolean isEmpty(final File empty) {
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return empty.length() == 0;
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}
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46-
private void testContentEquals(final String content1, final String content2) throws IOException {
47-
assertTrue(FileChannels.contentEquals(null, null, BUFFER_SIZE));
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61+
private FileChannel reset(final FileChannel fc) throws IOException {
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return fc.position(0);
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}
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@ParameterizedTest()
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@MethodSource("getBufferSizes")
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public void testContentEquals(final int bufferSize) throws IOException {
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final Path bigFile1 = Files.createTempFile(getClass().getSimpleName(), "-1.bin");
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final Path bigFile2 = Files.createTempFile(getClass().getSimpleName(), "-2.bin");
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final Path bigFile3 = Files.createTempFile(getClass().getSimpleName(), "-3.bin");
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try {
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// This length must match any restriction from the Surefire configuration.
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final int newLength = 5_000_000;
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final byte[] bytes1 = new byte[newLength];
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final byte[] bytes2 = new byte[newLength];
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// Make sure bytes1 and bytes2 are different despite the shuffle
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ArrayUtils.shuffle(bytes1);
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bytes1[0] = 1;
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ArrayUtils.shuffle(bytes2);
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bytes2[0] = 2;
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Files.write(bigFile1, bytes1);
82+
Files.write(bigFile2, bytes2);
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try (FileChannel fc1 = FileChannel.open(bigFile1); FileChannel fc2 = FileChannel.open(bigFile2)) {
84+
assertFalse(FileChannels.contentEquals(fc1, fc2, bufferSize));
85+
assertFalse(FileChannels.contentEquals(reset(fc2), reset(fc1), bufferSize));
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assertTrue(FileChannels.contentEquals(reset(fc1), reset(fc1), bufferSize));
87+
}
88+
// Make the LAST byte different.
89+
byte[] bytes3 = bytes1.clone();
90+
final int last = bytes3.length - 1;
91+
bytes3[last] = reverse(bytes3[last]);
92+
Files.write(bigFile3, bytes3);
93+
try (FileChannel fc1 = FileChannel.open(bigFile1); FileChannel fc3 = FileChannel.open(bigFile3)) {
94+
assertFalse(FileChannels.contentEquals(fc1, fc3, bufferSize));
95+
assertFalse(FileChannels.contentEquals(reset(fc3), reset(fc1), bufferSize));
96+
}
97+
// Make a byte in the middle different
98+
bytes3 = bytes1.clone();
99+
final int middle = bytes3.length / 2;
100+
bytes3[middle] = reverse(bytes3[middle]);
101+
Files.write(bigFile3, bytes3);
102+
try (FileChannel fc1 = FileChannel.open(bigFile1); FileChannel fc3 = FileChannel.open(bigFile3)) {
103+
assertFalse(FileChannels.contentEquals(fc1, fc3, bufferSize));
104+
assertFalse(FileChannels.contentEquals(reset(fc3), reset(fc1), bufferSize));
105+
}
106+
} finally {
107+
// Delete ASAP
108+
Files.deleteIfExists(bigFile1);
109+
Files.deleteIfExists(bigFile2);
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Files.deleteIfExists(bigFile3);
111+
}
112+
}
113+
114+
private void testContentEquals(final String content1, final String content2, final int bufferSize) throws IOException {
115+
assertTrue(FileChannels.contentEquals(null, null, bufferSize));
49116
// Prepare test files with same size but different content
50117
// (first 3 bytes are different, followed by a large amount of equal content)
51118
final File file1 = new File(tempDirFile, "test1.txt");
52119
final File file2 = new File(tempDirFile, "test2.txt");
53120
FileUtils.writeStringToFile(file1, content1, US_ASCII);
54121
FileUtils.writeStringToFile(file2, content2, US_ASCII);
55-
56122
// File checksums are different
57123
assertNotEquals(FileUtils.checksumCRC32(file1), FileUtils.checksumCRC32(file2));
58-
59124
try (FileInputStream stream1 = new FileInputStream(file1);
60125
FileInputStream stream2 = new FileInputStream(file2);
61126
FileChannel channel1 = stream1.getChannel();
62127
FileChannel channel2 = stream2.getChannel()) {
63-
assertFalse(FileChannels.contentEquals(channel1, channel2, BUFFER_SIZE));
128+
assertFalse(FileChannels.contentEquals(channel1, channel2, bufferSize));
64129
}
65130
try (FileInputStream stream1 = new FileInputStream(file1);
66131
FileInputStream stream2 = new FileInputStream(file2);
67132
FileChannel channel1 = stream1.getChannel();
68133
FileChannel channel2 = stream2.getChannel()) {
69-
assertTrue(FileChannels.contentEquals(channel1, channel1, BUFFER_SIZE));
70-
assertTrue(FileChannels.contentEquals(channel2, channel2, BUFFER_SIZE));
134+
assertTrue(FileChannels.contentEquals(channel1, channel1, bufferSize));
135+
assertTrue(FileChannels.contentEquals(channel2, channel2, bufferSize));
71136
}
72137
}
73138

74-
@Test
75-
public void testContentEqualsDifferentPostfix() throws IOException {
76-
testContentEquals(CONTENT + "ABC", CONTENT + "XYZ");
139+
@ParameterizedTest()
140+
@MethodSource("getBufferSizes")
141+
public void testContentEqualsDifferentPostfix(final int bufferSize) throws IOException {
142+
testContentEquals(CONTENT + "ABC", CONTENT + "XYZ", bufferSize);
77143
}
78144

79-
@Test
80-
public void testContentEqualsDifferentPrefix() throws IOException {
81-
testContentEquals("ABC" + CONTENT, "XYZ" + CONTENT);
145+
@ParameterizedTest()
146+
@MethodSource("getBufferSizes")
147+
public void testContentEqualsDifferentPrefix(final int bufferSize) throws IOException {
148+
testContentEquals("ABC" + CONTENT, "XYZ" + CONTENT, bufferSize);
82149
}
83150

84-
@Test
85-
public void testContentEqualsEmpty() throws IOException {
86-
assertTrue(FileChannels.contentEquals(null, null, BUFFER_SIZE));
87-
151+
@ParameterizedTest()
152+
@MethodSource("getBufferSizes")
153+
public void testContentEqualsEmpty(final int bufferSize) throws IOException {
154+
assertTrue(FileChannels.contentEquals(null, null, bufferSize));
155+
// setup fixtures
88156
final File empty = new File(tempDirFile, "empty.txt");
89157
final File notEmpty = new File(tempDirFile, "not-empty.txt");
90158
FileUtils.writeStringToFile(empty, StringUtils.EMPTY, US_ASCII);
91159
FileUtils.writeStringToFile(notEmpty, "X", US_ASCII);
92160
assertTrue(isEmpty(empty));
93161
assertFalse(isEmpty(notEmpty));
94-
95162
// File checksums are different
96163
assertNotEquals(FileUtils.checksumCRC32(empty), FileUtils.checksumCRC32(notEmpty));
97-
98164
try (FileInputStream streamEmpty = new FileInputStream(empty);
99165
FileInputStream streamNotEmpty = new FileInputStream(notEmpty);
100166
FileChannel channelEmpty = streamEmpty.getChannel();
101167
FileChannel channelNotEmpty = streamNotEmpty.getChannel()) {
102-
assertFalse(FileChannels.contentEquals(channelEmpty, channelNotEmpty, BUFFER_SIZE));
103-
assertFalse(FileChannels.contentEquals(null, channelNotEmpty, BUFFER_SIZE));
104-
assertFalse(FileChannels.contentEquals(channelNotEmpty, null, BUFFER_SIZE));
105-
assertTrue(FileChannels.contentEquals(channelEmpty, channelEmpty, BUFFER_SIZE));
106-
assertTrue(FileChannels.contentEquals(null, channelEmpty, BUFFER_SIZE));
107-
assertTrue(FileChannels.contentEquals(channelEmpty, null, BUFFER_SIZE));
108-
assertTrue(FileChannels.contentEquals(channelNotEmpty, channelNotEmpty, BUFFER_SIZE));
168+
assertFalse(FileChannels.contentEquals(channelEmpty, channelNotEmpty, bufferSize));
169+
assertFalse(FileChannels.contentEquals(null, channelNotEmpty, bufferSize));
170+
assertFalse(FileChannels.contentEquals(channelNotEmpty, null, bufferSize));
171+
assertTrue(FileChannels.contentEquals(channelEmpty, channelEmpty, bufferSize));
172+
assertTrue(FileChannels.contentEquals(null, channelEmpty, bufferSize));
173+
assertTrue(FileChannels.contentEquals(channelEmpty, null, bufferSize));
174+
assertTrue(FileChannels.contentEquals(channelNotEmpty, channelNotEmpty, bufferSize));
109175
}
110176
}
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112177
}

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