OpenWrite doesn't prevent writing

[Benjamin-Berry]

Describe the bug
Stream.CopyTpAsync still works with a write only stream.

To Reproduce
var fs = new MockFileSystem();

...

using var estream = entry.Open();
using var fstream = file.OpenWrite();
var temp = fstream.CanRead; // false
await fstream.CopyToAsync(estream);

Expected behavior
MockFileSystem and FileSystem would behave the same.

Additional context
I'm writing into a ZipArchive but that shouldn't matter.
Swapping to use FileSystem in the Unit test does throw a permissions exception.

[vbreuss]

@Benjamin-Berry :
Could you please provide a complete repro example as it is unclear from your description what entry and file should be or what settings you applied.

[Benjamin-Berry]

I can't give you any proprietary code.

var fs = new MockFileSystem();
var directory = fs.DirectoryInfo.New("somepath");
foreach (var file in directory.GetFiles(".", SearchOption.AllDirectories))
{
using var estream = new MemoryStream();
using var fstream = file.OpenWrite();
var temp = fstream.CanRead; // false
await fstream.CopyToAsync(estream);
}