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Diffstat (limited to 'java/core/src/test/java/com/google/protobuf/CodedOutputStreamTest.java')
| -rw-r--r-- | java/core/src/test/java/com/google/protobuf/CodedOutputStreamTest.java | 546 |
1 files changed, 546 insertions, 0 deletions
diff --git a/java/core/src/test/java/com/google/protobuf/CodedOutputStreamTest.java b/java/core/src/test/java/com/google/protobuf/CodedOutputStreamTest.java new file mode 100644 index 00000000..6018ea55 --- /dev/null +++ b/java/core/src/test/java/com/google/protobuf/CodedOutputStreamTest.java @@ -0,0 +1,546 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +package com.google.protobuf; + +import protobuf_unittest.UnittestProto.SparseEnumMessage; +import protobuf_unittest.UnittestProto.TestAllTypes; +import protobuf_unittest.UnittestProto.TestPackedTypes; +import protobuf_unittest.UnittestProto.TestSparseEnum; + +import junit.framework.TestCase; + +import java.io.ByteArrayInputStream; +import java.io.ByteArrayOutputStream; +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; + +/** + * Unit test for {@link CodedOutputStream}. + * + * @author kenton@google.com Kenton Varda + */ +public class CodedOutputStreamTest extends TestCase { + /** + * Helper to construct a byte array from a bunch of bytes. The inputs are + * actually ints so that I can use hex notation and not get stupid errors + * about precision. + */ + private byte[] bytes(int... bytesAsInts) { + byte[] bytes = new byte[bytesAsInts.length]; + for (int i = 0; i < bytesAsInts.length; i++) { + bytes[i] = (byte) bytesAsInts[i]; + } + return bytes; + } + + /** Arrays.asList() does not work with arrays of primitives. :( */ + private List<Byte> toList(byte[] bytes) { + List<Byte> result = new ArrayList<Byte>(); + for (byte b : bytes) { + result.add(b); + } + return result; + } + + private void assertEqualBytes(byte[] a, byte[] b) { + assertEquals(toList(a), toList(b)); + } + + /** + * Writes the given value using writeRawVarint32() and writeRawVarint64() and + * checks that the result matches the given bytes. + */ + private void assertWriteVarint(byte[] data, long value) throws Exception { + // Only test 32-bit write if the value fits into an int. + if (value == (int) value) { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawVarint32((int) value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + + // Also try computing size. + assertEquals(data.length, + CodedOutputStream.computeRawVarint32Size((int) value)); + } + + { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawVarint64(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + + // Also try computing size. + assertEquals(data.length, + CodedOutputStream.computeRawVarint64Size(value)); + } + + // Try different block sizes. + for (int blockSize = 1; blockSize <= 16; blockSize *= 2) { + // Only test 32-bit write if the value fits into an int. + if (value == (int) value) { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = + CodedOutputStream.newInstance(rawOutput, blockSize); + output.writeRawVarint32((int) value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + } + + { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = + CodedOutputStream.newInstance(rawOutput, blockSize); + output.writeRawVarint64(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + } + } + } + + private void assertVarintRoundTrip(long value) throws Exception { + { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawVarint64(value); + output.flush(); + byte[] bytes = rawOutput.toByteArray(); + assertEquals(bytes.length, CodedOutputStream.computeRawVarint64Size(value)); + CodedInputStream input = CodedInputStream.newInstance(new ByteArrayInputStream(bytes)); + assertEquals(value, input.readRawVarint64()); + } + + if (value == (int) value) { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawVarint32((int) value); + output.flush(); + byte[] bytes = rawOutput.toByteArray(); + assertEquals(bytes.length, CodedOutputStream.computeRawVarint32Size((int) value)); + CodedInputStream input = CodedInputStream.newInstance(new ByteArrayInputStream(bytes)); + assertEquals(value, input.readRawVarint32()); + } + } + + /** Checks that invariants are maintained for varint round trip input and output. */ + public void testVarintRoundTrips() throws Exception { + assertVarintRoundTrip(0L); + for (int bits = 0; bits < 64; bits++) { + long value = 1L << bits; + assertVarintRoundTrip(value); + assertVarintRoundTrip(value + 1); + assertVarintRoundTrip(value - 1); + assertVarintRoundTrip(-value); + } + } + + /** Tests writeRawVarint32() and writeRawVarint64(). */ + public void testWriteVarint() throws Exception { + assertWriteVarint(bytes(0x00), 0); + assertWriteVarint(bytes(0x01), 1); + assertWriteVarint(bytes(0x7f), 127); + // 14882 + assertWriteVarint(bytes(0xa2, 0x74), (0x22 << 0) | (0x74 << 7)); + // 2961488830 + assertWriteVarint(bytes(0xbe, 0xf7, 0x92, 0x84, 0x0b), + (0x3e << 0) | (0x77 << 7) | (0x12 << 14) | (0x04 << 21) | + (0x0bL << 28)); + + // 64-bit + // 7256456126 + assertWriteVarint(bytes(0xbe, 0xf7, 0x92, 0x84, 0x1b), + (0x3e << 0) | (0x77 << 7) | (0x12 << 14) | (0x04 << 21) | + (0x1bL << 28)); + // 41256202580718336 + assertWriteVarint( + bytes(0x80, 0xe6, 0xeb, 0x9c, 0xc3, 0xc9, 0xa4, 0x49), + (0x00 << 0) | (0x66 << 7) | (0x6b << 14) | (0x1c << 21) | + (0x43L << 28) | (0x49L << 35) | (0x24L << 42) | (0x49L << 49)); + // 11964378330978735131 + assertWriteVarint( + bytes(0x9b, 0xa8, 0xf9, 0xc2, 0xbb, 0xd6, 0x80, 0x85, 0xa6, 0x01), + (0x1b << 0) | (0x28 << 7) | (0x79 << 14) | (0x42 << 21) | + (0x3bL << 28) | (0x56L << 35) | (0x00L << 42) | + (0x05L << 49) | (0x26L << 56) | (0x01L << 63)); + } + + /** + * Parses the given bytes using writeRawLittleEndian32() and checks + * that the result matches the given value. + */ + private void assertWriteLittleEndian32(byte[] data, int value) + throws Exception { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawLittleEndian32(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + + // Try different block sizes. + for (int blockSize = 1; blockSize <= 16; blockSize *= 2) { + rawOutput = new ByteArrayOutputStream(); + output = CodedOutputStream.newInstance(rawOutput, blockSize); + output.writeRawLittleEndian32(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + } + } + + /** + * Parses the given bytes using writeRawLittleEndian64() and checks + * that the result matches the given value. + */ + private void assertWriteLittleEndian64(byte[] data, long value) + throws Exception { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = CodedOutputStream.newInstance(rawOutput); + output.writeRawLittleEndian64(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + + // Try different block sizes. + for (int blockSize = 1; blockSize <= 16; blockSize *= 2) { + rawOutput = new ByteArrayOutputStream(); + output = CodedOutputStream.newInstance(rawOutput, blockSize); + output.writeRawLittleEndian64(value); + output.flush(); + assertEqualBytes(data, rawOutput.toByteArray()); + } + } + + /** Tests writeRawLittleEndian32() and writeRawLittleEndian64(). */ + public void testWriteLittleEndian() throws Exception { + assertWriteLittleEndian32(bytes(0x78, 0x56, 0x34, 0x12), 0x12345678); + assertWriteLittleEndian32(bytes(0xf0, 0xde, 0xbc, 0x9a), 0x9abcdef0); + + assertWriteLittleEndian64( + bytes(0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12), + 0x123456789abcdef0L); + assertWriteLittleEndian64( + bytes(0x78, 0x56, 0x34, 0x12, 0xf0, 0xde, 0xbc, 0x9a), + 0x9abcdef012345678L); + } + + /** Test encodeZigZag32() and encodeZigZag64(). */ + public void testEncodeZigZag() throws Exception { + assertEquals(0, CodedOutputStream.encodeZigZag32( 0)); + assertEquals(1, CodedOutputStream.encodeZigZag32(-1)); + assertEquals(2, CodedOutputStream.encodeZigZag32( 1)); + assertEquals(3, CodedOutputStream.encodeZigZag32(-2)); + assertEquals(0x7FFFFFFE, CodedOutputStream.encodeZigZag32(0x3FFFFFFF)); + assertEquals(0x7FFFFFFF, CodedOutputStream.encodeZigZag32(0xC0000000)); + assertEquals(0xFFFFFFFE, CodedOutputStream.encodeZigZag32(0x7FFFFFFF)); + assertEquals(0xFFFFFFFF, CodedOutputStream.encodeZigZag32(0x80000000)); + + assertEquals(0, CodedOutputStream.encodeZigZag64( 0)); + assertEquals(1, CodedOutputStream.encodeZigZag64(-1)); + assertEquals(2, CodedOutputStream.encodeZigZag64( 1)); + assertEquals(3, CodedOutputStream.encodeZigZag64(-2)); + assertEquals(0x000000007FFFFFFEL, + CodedOutputStream.encodeZigZag64(0x000000003FFFFFFFL)); + assertEquals(0x000000007FFFFFFFL, + CodedOutputStream.encodeZigZag64(0xFFFFFFFFC0000000L)); + assertEquals(0x00000000FFFFFFFEL, + CodedOutputStream.encodeZigZag64(0x000000007FFFFFFFL)); + assertEquals(0x00000000FFFFFFFFL, + CodedOutputStream.encodeZigZag64(0xFFFFFFFF80000000L)); + assertEquals(0xFFFFFFFFFFFFFFFEL, + CodedOutputStream.encodeZigZag64(0x7FFFFFFFFFFFFFFFL)); + assertEquals(0xFFFFFFFFFFFFFFFFL, + CodedOutputStream.encodeZigZag64(0x8000000000000000L)); + + // Some easier-to-verify round-trip tests. The inputs (other than 0, 1, -1) + // were chosen semi-randomly via keyboard bashing. + assertEquals(0, + CodedOutputStream.encodeZigZag32(CodedInputStream.decodeZigZag32(0))); + assertEquals(1, + CodedOutputStream.encodeZigZag32(CodedInputStream.decodeZigZag32(1))); + assertEquals(-1, + CodedOutputStream.encodeZigZag32(CodedInputStream.decodeZigZag32(-1))); + assertEquals(14927, + CodedOutputStream.encodeZigZag32(CodedInputStream.decodeZigZag32(14927))); + assertEquals(-3612, + CodedOutputStream.encodeZigZag32(CodedInputStream.decodeZigZag32(-3612))); + + assertEquals(0, + CodedOutputStream.encodeZigZag64(CodedInputStream.decodeZigZag64(0))); + assertEquals(1, + CodedOutputStream.encodeZigZag64(CodedInputStream.decodeZigZag64(1))); + assertEquals(-1, + CodedOutputStream.encodeZigZag64(CodedInputStream.decodeZigZag64(-1))); + assertEquals(14927, + CodedOutputStream.encodeZigZag64(CodedInputStream.decodeZigZag64(14927))); + assertEquals(-3612, + CodedOutputStream.encodeZigZag64(CodedInputStream.decodeZigZag64(-3612))); + + assertEquals(856912304801416L, + CodedOutputStream.encodeZigZag64( + CodedInputStream.decodeZigZag64( + 856912304801416L))); + assertEquals(-75123905439571256L, + CodedOutputStream.encodeZigZag64( + CodedInputStream.decodeZigZag64( + -75123905439571256L))); + } + + /** Tests writing a whole message with every field type. */ + public void testWriteWholeMessage() throws Exception { + TestAllTypes message = TestUtil.getAllSet(); + + byte[] rawBytes = message.toByteArray(); + assertEqualBytes(TestUtil.getGoldenMessage().toByteArray(), rawBytes); + + // Try different block sizes. + for (int blockSize = 1; blockSize < 256; blockSize *= 2) { + ByteArrayOutputStream rawOutput = new ByteArrayOutputStream(); + CodedOutputStream output = + CodedOutputStream.newInstance(rawOutput, blockSize); + message.writeTo(output); + output.flush(); + assertEqualBytes(rawBytes, rawOutput.toByteArray()); + } + } + + /** Tests writing a whole message with every packed field type. Ensures the + * wire format of packed fields is compatible with C++. */ + public void testWriteWholePackedFieldsMessage() throws Exception { + TestPackedTypes message = TestUtil.getPackedSet(); + + byte[] rawBytes = message.toByteArray(); + assertEqualBytes(TestUtil.getGoldenPackedFieldsMessage().toByteArray(), + rawBytes); + } + + /** Test writing a message containing a negative enum value. This used to + * fail because the size was not properly computed as a sign-extended varint. + */ + public void testWriteMessageWithNegativeEnumValue() throws Exception { + SparseEnumMessage message = SparseEnumMessage.newBuilder() + .setSparseEnum(TestSparseEnum.SPARSE_E) .build(); + assertTrue(message.getSparseEnum().getNumber() < 0); + byte[] rawBytes = message.toByteArray(); + SparseEnumMessage message2 = SparseEnumMessage.parseFrom(rawBytes); + assertEquals(TestSparseEnum.SPARSE_E, message2.getSparseEnum()); + } + + /** Test getTotalBytesWritten() */ + public void testGetTotalBytesWritten() throws Exception { + final int BUFFER_SIZE = 4 * 1024; + ByteArrayOutputStream outputStream = new ByteArrayOutputStream(BUFFER_SIZE); + CodedOutputStream codedStream = CodedOutputStream.newInstance(outputStream); + byte[] value = "abcde".getBytes(Internal.UTF_8); + for (int i = 0; i < 1024; ++i) { + codedStream.writeRawBytes(value, 0, value.length); + } + String string = + "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"; + // Ensure we take the slower fast path. + assertTrue(CodedOutputStream.computeRawVarint32Size(string.length()) + != CodedOutputStream.computeRawVarint32Size(string.length() * Utf8.MAX_BYTES_PER_CHAR)); + + codedStream.writeStringNoTag(string); + int stringSize = CodedOutputStream.computeStringSizeNoTag(string); + + // Make sure we have written more bytes than the buffer could hold. This is + // to make the test complete. + assertTrue(codedStream.getTotalBytesWritten() > BUFFER_SIZE); + + // Verify that the total bytes written is correct + assertEquals((value.length * 1024) + stringSize, codedStream.getTotalBytesWritten()); + } + + // TODO(dweis): Write a comprehensive test suite for CodedOutputStream that covers more than just + // this case. + public void testWriteStringNoTag_fastpath() throws Exception { + int bufferSize = 153; + String threeBytesPer = "\u0981"; + String string = threeBytesPer; + for (int i = 0; i < 50; i++) { + string += threeBytesPer; + } + // These checks ensure we will tickle the slower fast path. + assertEquals(1, CodedOutputStream.computeRawVarint32Size(string.length())); + assertEquals( + 2, CodedOutputStream.computeRawVarint32Size(string.length() * Utf8.MAX_BYTES_PER_CHAR)); + assertEquals(bufferSize, string.length() * Utf8.MAX_BYTES_PER_CHAR); + + CodedOutputStream output = + CodedOutputStream.newInstance(ByteBuffer.allocate(bufferSize), bufferSize); + output.writeStringNoTag(string); + } + + public void testWriteToByteBuffer() throws Exception { + final int bufferSize = 16 * 1024; + ByteBuffer buffer = ByteBuffer.allocate(bufferSize); + CodedOutputStream codedStream = CodedOutputStream.newInstance(buffer); + // Write raw bytes into the ByteBuffer. + final int length1 = 5000; + for (int i = 0; i < length1; i++) { + codedStream.writeRawByte((byte) 1); + } + final int length2 = 8 * 1024; + byte[] data = new byte[length2]; + for (int i = 0; i < length2; i++) { + data[i] = (byte) 2; + } + codedStream.writeRawBytes(data); + final int length3 = bufferSize - length1 - length2; + for (int i = 0; i < length3; i++) { + codedStream.writeRawByte((byte) 3); + } + codedStream.flush(); + + // Check that data is correctly written to the ByteBuffer. + assertEquals(0, buffer.remaining()); + buffer.flip(); + for (int i = 0; i < length1; i++) { + assertEquals((byte) 1, buffer.get()); + } + for (int i = 0; i < length2; i++) { + assertEquals((byte) 2, buffer.get()); + } + for (int i = 0; i < length3; i++) { + assertEquals((byte) 3, buffer.get()); + } + } + + public void testWriteByteBuffer() throws Exception { + byte[] value = "abcde".getBytes(Internal.UTF_8); + ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); + CodedOutputStream codedStream = CodedOutputStream.newInstance(outputStream); + ByteBuffer byteBuffer = ByteBuffer.wrap(value, 0, 1); + // This will actually write 5 bytes into the CodedOutputStream as the + // ByteBuffer's capacity() is 5. + codedStream.writeRawBytes(byteBuffer); + // The above call shouldn't affect the ByteBuffer's state. + assertEquals(0, byteBuffer.position()); + assertEquals(1, byteBuffer.limit()); + + // The correct way to write part of an array using ByteBuffer. + codedStream.writeRawBytes(ByteBuffer.wrap(value, 2, 1).slice()); + + codedStream.flush(); + byte[] result = outputStream.toByteArray(); + assertEquals(6, result.length); + for (int i = 0; i < 5; i++) { + assertEquals(value[i], result[i]); + } + assertEquals(value[2], result[5]); + } + + public void testWriteByteArrayWithOffsets() throws Exception { + byte[] fullArray = bytes(0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88); + byte[] destination = new byte[4]; + CodedOutputStream codedStream = CodedOutputStream.newInstance(destination); + codedStream.writeByteArrayNoTag(fullArray, 2, 2); + assertEqualBytes(bytes(0x02, 0x33, 0x44, 0x00), destination); + assertEquals(3, codedStream.getTotalBytesWritten()); + } + + public void testSerializeInvalidUtf8() throws Exception { + String[] invalidStrings = new String[] { + newString(Character.MIN_HIGH_SURROGATE), + "foobar" + newString(Character.MIN_HIGH_SURROGATE), + newString(Character.MIN_LOW_SURROGATE), + "foobar" + newString(Character.MIN_LOW_SURROGATE), + newString(Character.MIN_HIGH_SURROGATE, Character.MIN_HIGH_SURROGATE) + }; + + CodedOutputStream outputWithStream = CodedOutputStream.newInstance(new ByteArrayOutputStream()); + CodedOutputStream outputWithArray = CodedOutputStream.newInstance(new byte[10000]); + for (String s : invalidStrings) { + // TODO(dweis): These should all fail; instead they are corrupting data. + CodedOutputStream.computeStringSizeNoTag(s); + outputWithStream.writeStringNoTag(s); + outputWithArray.writeStringNoTag(s); + } + } + + private static String newString(char... chars) { + return new String(chars); + } + + /** Regression test for https://github.com/google/protobuf/issues/292 */ + public void testCorrectExceptionThrowWhenEncodingStringsWithoutEnoughSpace() throws Exception { + String testCase = "Foooooooo"; + assertEquals(CodedOutputStream.computeRawVarint32Size(testCase.length()), + CodedOutputStream.computeRawVarint32Size(testCase.length() * 3)); + assertEquals(11, CodedOutputStream.computeStringSize(1, testCase)); + // Tag is one byte, varint describing string length is 1 byte, string length is 9 bytes. + // An array of size 1 will cause a failure when trying to write the varint. + for (int i = 0; i < 11; i++) { + CodedOutputStream output = CodedOutputStream.newInstance(new byte[i]); + try { + output.writeString(1, testCase); + fail("Should have thrown an out of space exception"); + } catch (CodedOutputStream.OutOfSpaceException expected) {} + } + } + + public void testDifferentStringLengths() throws Exception { + // Test string serialization roundtrip using strings of the following lengths, + // with ASCII and Unicode characters requiring different UTF-8 byte counts per + // char, hence causing the length delimiter varint to sometimes require more + // bytes for the Unicode strings than the ASCII string of the same length. + int[] lengths = new int[] { + 0, + 1, + (1 << 4) - 1, // 1 byte for ASCII and Unicode + (1 << 7) - 1, // 1 byte for ASCII, 2 bytes for Unicode + (1 << 11) - 1, // 2 bytes for ASCII and Unicode + (1 << 14) - 1, // 2 bytes for ASCII, 3 bytes for Unicode + (1 << 17) - 1, // 3 bytes for ASCII and Unicode + }; + for (int i : lengths) { + testEncodingOfString('q', i); // 1 byte per char + testEncodingOfString('\u07FF', i); // 2 bytes per char + testEncodingOfString('\u0981', i); // 3 bytes per char + } + } + + private void testEncodingOfString(char c, int length) throws Exception { + String fullString = fullString(c, length); + TestAllTypes testAllTypes = TestAllTypes.newBuilder() + .setOptionalString(fullString) + .build(); + assertEquals( + fullString, TestAllTypes.parseFrom(testAllTypes.toByteArray()).getOptionalString()); + } + + private String fullString(char c, int length) { + char[] result = new char[length]; + Arrays.fill(result, c); + return new String(result); + } +} |