Stream

Describes the possible expectations for Stream and BufferedStream.

Expectation	Negated	Summary
IsReadable	IsNotReadable	supports reading
IsWritable	IsNotWritable	supports writing
IsSeekable	IsNotSeekable	supports seeking
IsReadOnly	IsNotReadOnly	supports reading, but not writing
IsWriteOnly	IsNotWriteOnly	supports writing, but not reading
HasLength	negated comparison	has the expected length in bytes
HasPosition	negated comparison	is at the expected position
HasBufferSize	negated comparison	a BufferedStream with the expected buffer size

Capabilities

You can verify what the Stream supports, or that it does not support it:

Stream playlist = new MemoryStream();

await Expect.That(playlist).IsReadable();
await Expect.That(playlist).IsSeekable();
await Expect.That(playlist).IsWritable();
await Expect.That(playlist).IsNotReadOnly();
await Expect.That(File.Open("album.txt", FileMode.OpenOrCreate, FileAccess.Read)).IsReadOnly()
  .Because("the file was opened with Read access");
await Expect.That(File.Open("album.log", FileMode.OpenOrCreate, FileAccess.Write)).IsWriteOnly()
  .Because("the file was opened with Write access");

Length

You can verify the length of the Stream:

Stream playlist = new MemoryStream("foo"u8.ToArray());

await Expect.That(playlist).HasLength(3);
await Expect.That(playlist).HasLength().Between(2).And(4);

Position

You can verify the position of the Stream:

Stream playlist = new MemoryStream("foo"u8.ToArray());
playlist.Seek(2, SeekOrigin.Current);

await Expect.That(playlist).HasPosition(2);
await Expect.That(playlist).HasPosition().GreaterThan(1);

Buffer size

.NET 8 or later

The buffer size expectations are only available on .NET 8 or later.

You can verify the buffer size of the BufferedStream:

BufferedStream playlist = new(new MemoryStream("foo"u8.ToArray()), 2);

await Expect.That(playlist).HasBufferSize(2);
await Expect.That(playlist).HasBufferSize().NotEqualTo(3);

Comparisons

The Has… expectations for a number or a TimeSpan, e.g. HasLength(), HasCount(), HasYear() or HasMajor(), continue with one of the following comparisons, each with a negated counterpart:

Comparison	Negated	Succeeds when the value is
EqualTo(x)	NotEqualTo(x)	equal to x
GreaterThan(x)	NotGreaterThan(x)	greater than x
GreaterThanOrEqualTo(x)	NotGreaterThanOrEqualTo(x)	greater than or equal to x
LessThan(x)	NotLessThan(x)	less than x
LessThanOrEqualTo(x)	NotLessThanOrEqualTo(x)	less than or equal to x
Between(min).And(max)	NotBetween(min).And(max)	between min and max, both bounds included

Passing the value directly, e.g. HasLength(10), is a shorthand for EqualTo.

The expected value is nullable, e.g. to pass a value mapped from a property. As the actual value is never null, EqualTo(null) fails and NotEqualTo(null) succeeds, while a comparison of order against null, such as GreaterThan(null) or Between(null).And(3), fails even when negated.