public void Write_WithPartialData()
{
MemoryStream innerStream = new MemoryStream();
Stream transcodingStream = Encoding.CreateTranscodingStream(
innerStream,
innerStreamEncoding: CustomAsciiEncoding /* performs custom substitution */,
outerStreamEncoding: Encoding.UTF8 /* performs U+FFFD substition */,
leaveOpen: true);
// First, write some incomplete data
transcodingStream.Write(new byte[] { 0x78, 0x79, 0x7A, 0xC3 }); // [C3] shouldn't be flushed yet
Assert.Equal("xyz", ErrorCheckingAsciiEncoding.GetString(innerStream.ToArray()));
// Flushing should have no effect
transcodingStream.Flush();
Assert.Equal("xyz", ErrorCheckingAsciiEncoding.GetString(innerStream.ToArray()));
// Provide the second byte of the multi-byte sequence
transcodingStream.WriteByte(0xA0); // [C3 A0] = U+00E0
Assert.Equal("xyz[00E0]", ErrorCheckingAsciiEncoding.GetString(innerStream.ToArray()));
// Provide an incomplete sequence, then close the stream.
// Closing the stream should flush the underlying buffers and write the replacement char.
transcodingStream.Write(new byte[] { 0xE0, 0xBF }); // first 2 bytes of incomplete 3-byte sequence
Assert.Equal("xyz[00E0]", ErrorCheckingAsciiEncoding.GetString(innerStream.ToArray())); // wasn't flushed yet
transcodingStream.Close();
Assert.Equal("xyz[00E0][FFFD]", ErrorCheckingAsciiEncoding.GetString(innerStream.ToArray()));
}
private void RunReadTest(Func <Stream, MemoryStream, int> callback)
{
MemoryStream sink = new MemoryStream();
MemoryStream innerStream = new MemoryStream();
Stream transcodingStream = Encoding.CreateTranscodingStream(innerStream,
innerStreamEncoding: Encoding.UTF8,
outerStreamEncoding: CustomAsciiEncoding);
// Test with a small string, then test with a large string
RunOneTestIteration(128);
RunOneTestIteration(10 * 1024 * 1024);
Assert.Equal(-1, transcodingStream.ReadByte()); // should've reached EOF
// Now put some invalid data into the inner stream as EOF.
innerStream.SetLength(0); // reset
innerStream.WriteByte(0xC0);
innerStream.Position = 0;
sink.SetLength(0); // reset
int numBytesReadJustNow;
do
{
numBytesReadJustNow = callback(transcodingStream, sink);
Assert.True(numBytesReadJustNow >= 0);
} while (numBytesReadJustNow > 0);
Assert.Equal("[FFFD]", ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
Assert.Equal(-1, transcodingStream.ReadByte()); // should've reached EOF
void RunOneTestIteration(int stringLength)
{
sink.SetLength(0); // reset
string expectedStringContents = GetVeryLongAsciiString(stringLength);
innerStream.SetLength(0); // reset
innerStream.Write(Encoding.UTF8.GetBytes(expectedStringContents));
innerStream.Position = 0;
int numBytesReadJustNow;
do
{
numBytesReadJustNow = callback(transcodingStream, sink);
Assert.True(numBytesReadJustNow >= 0);
} while (numBytesReadJustNow > 0);
Assert.Equal(expectedStringContents, ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
}
}
public async Task WriteAsync_WithPartialData()
{
MemoryStream sink = new MemoryStream();
CancellationToken expectedCancellationToken = new CancellationTokenSource().Token;
var innerStreamMock = new Mock <Stream>(MockBehavior.Strict);
innerStreamMock.Setup(o => o.CanWrite).Returns(true);
innerStreamMock.Setup(o => o.WriteAsync(It.IsAny <ReadOnlyMemory <byte> >(), expectedCancellationToken))
.Returns <ReadOnlyMemory <byte>, CancellationToken>(sink.WriteAsync);
Stream transcodingStream = Encoding.CreateTranscodingStream(
innerStreamMock.Object,
innerStreamEncoding: CustomAsciiEncoding /* performs custom substitution */,
outerStreamEncoding: Encoding.UTF8 /* performs U+FFFD substition */,
leaveOpen: true);
// First, write some incomplete data
await transcodingStream.WriteAsync(new byte[] { 0x78, 0x79, 0x7A, 0xC3 }, expectedCancellationToken); // [C3] shouldn't be flushed yet
Assert.Equal("xyz", ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
// Provide the second byte of the multi-byte sequence
await transcodingStream.WriteAsync(new byte[] { 0xA0 }, expectedCancellationToken); // [C3 A0] = U+00E0
Assert.Equal("xyz[00E0]", ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
// Provide an incomplete sequence, then close the stream.
// Closing the stream should flush the underlying buffers and write the replacement char.
await transcodingStream.WriteAsync(new byte[] { 0xE0, 0xBF }, expectedCancellationToken); // first 2 bytes of incomplete 3-byte sequence
Assert.Equal("xyz[00E0]", ErrorCheckingAsciiEncoding.GetString(sink.ToArray())); // wasn't flushed yet
// The call to DisposeAsync() will call innerStream.WriteAsync without a CancellationToken.
innerStreamMock.Setup(o => o.WriteAsync(It.IsAny <ReadOnlyMemory <byte> >(), CancellationToken.None))
.Returns <ReadOnlyMemory <byte>, CancellationToken>(sink.WriteAsync);
await transcodingStream.DisposeAsync();
Assert.Equal("xyz[00E0][FFFD]", ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
}
private async Task RunReadTestAsync(Func <Stream, CancellationToken, MemoryStream, ValueTask <int> > callback, bool suppressExpectedCancellationTokenAsserts = false)
{
CancellationToken expectedCancellationToken = new CancellationTokenSource().Token;
MemoryStream sink = new MemoryStream();
MemoryStream innerStream = new MemoryStream();
var delegatingInnerStreamMock = new Mock <Stream>(MockBehavior.Strict);
delegatingInnerStreamMock.Setup(o => o.CanRead).Returns(true);
if (suppressExpectedCancellationTokenAsserts)
{
delegatingInnerStreamMock.Setup(o => o.ReadAsync(It.IsAny <Memory <byte> >(), It.IsAny <CancellationToken>()))
.Returns <Memory <byte>, CancellationToken>(innerStream.ReadAsync);
}
else
{
delegatingInnerStreamMock.Setup(o => o.ReadAsync(It.IsAny <Memory <byte> >(), expectedCancellationToken))
.Returns <Memory <byte>, CancellationToken>(innerStream.ReadAsync);
}
Stream transcodingStream = Encoding.CreateTranscodingStream(
innerStream: delegatingInnerStreamMock.Object,
innerStreamEncoding: Encoding.UTF8,
outerStreamEncoding: CustomAsciiEncoding);
// Test with a small string, then test with a large string
await RunOneTestIteration(128);
await RunOneTestIteration(10 * 1024 * 1024);
Assert.Equal(-1, await transcodingStream.ReadByteAsync(expectedCancellationToken)); // should've reached EOF
// Now put some invalid data into the inner stream as EOF.
innerStream.SetLength(0); // reset
innerStream.WriteByte(0xC0);
innerStream.Position = 0;
sink.SetLength(0); // reset
int numBytesReadJustNow;
do
{
numBytesReadJustNow = await callback(transcodingStream, expectedCancellationToken, sink);
Assert.True(numBytesReadJustNow >= 0);
} while (numBytesReadJustNow > 0);
Assert.Equal("[FFFD]", ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
Assert.Equal(-1, await transcodingStream.ReadByteAsync(expectedCancellationToken)); // should've reached EOF
async Task RunOneTestIteration(int stringLength)
{
sink.SetLength(0); // reset
string expectedStringContents = GetVeryLongAsciiString(stringLength);
innerStream.SetLength(0); // reset
innerStream.Write(Encoding.UTF8.GetBytes(expectedStringContents));
innerStream.Position = 0;
int numBytesReadJustNow;
do
{
numBytesReadJustNow = await callback(transcodingStream, expectedCancellationToken, sink);
Assert.True(numBytesReadJustNow >= 0);
} while (numBytesReadJustNow > 0);
Assert.Equal(expectedStringContents, ErrorCheckingAsciiEncoding.GetString(sink.ToArray()));
}
}
