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FlushAsync doesn't update file contents #959
Description
Describe the bug
While Flush does update the contents of the file, allowing other streams to read it later, FlushAsync does not.
To Reproduce
var fs = new MockFileSystem();
var file = fs.FileInfo.New("/file");
await using var first = file.OpenWrite();
await first.WriteAsync(new byte[] { 42 });
await first.FlushAsync();
await using var second = file.OpenRead();
var buffer = new byte[1];
Assert.Equal(1, await second.ReadAsync(buffer));
Assert.Equal(42, buffer[0]);Expected behavior
Behave identically to the synchronous version, which does successfully pass.
var fs = new MockFileSystem();
var file = fs.FileInfo.New("/file");
using var first = file.OpenWrite();
first.Write(new byte[] { 42 });
first.Flush();
using var second = file.OpenRead();
var buffer = new byte[1];
Assert.Equal(1, second.Read(buffer));
Assert.Equal(42, buffer[0]);
Activity
[-]FlushAsync doesn't update file contents[/-][+]`FlushAsync` doesn't update file contents[/+]fgreinacher commentedon Mar 10, 2023
Thanks for reporting!
Probably we need to override
FlushAsyncsimilar to how we overrideFlush.cryocz commentedon Mar 10, 2023
I'll be submitting a PR for this in just a bit. It should be noted that correctly implementing
FlushAsyncis more of a band-aid over the fundamental underlying issue: mocked file streams do not share their data buffer. This means that concurrentMockFileStreams, opened on the same file, do not behave like real streams at all.fix: ensure `FlushAsync` behaves like `Flush` (#960)
github-actions commentedon Apr 11, 2023
This is addressed in release v19.2.4.