aweXpect.Testably

Drop-in aweXpect expectations for the file-system and time-system mocks from Testably.Abstractions: MockFileSystem, IFileInfo, IDirectoryInfo, IDriveInfo, IFileVersionInfo, IFileSystemWatcher, IFileSystemStatistics and ITimerMock.

File system (IFileSystem)

Verify that a file, directory or drive is present in the file system. Every positive assertion has a DoesNot… counterpart:

IFileSystem fileSystem = new MockFileSystem();
fileSystem.Directory.CreateDirectory("my/path");
fileSystem.File.WriteAllText("my-file.txt", "some content");

await That(fileSystem).HasDirectory("my/path");
await That(fileSystem).HasFile("my-file.txt");

await That(fileSystem).DoesNotHaveDirectory("not/here");
await That(fileSystem).DoesNotHaveFile("missing.txt");

File chain

HasFile(path) returns a result that lets you chain assertions about the file's content and timestamps without re-resolving it:

IFileSystem fileSystem = new MockFileSystem();
fileSystem.File.WriteAllText("my-file.txt", "some content");

await That(fileSystem).HasFile("my-file.txt").WithContent("some content").IgnoringCase();
await That(fileSystem).HasFile("my-file.txt").WithContent().NotEqualTo("some unexpected content");
await That(fileSystem).HasFile("my-file.txt").WithContent(new byte[] { 0x73, 0x6F, 0x6D, 0x65 });

You can compare against another file on the same file system:

fileSystem.File.WriteAllText("my-other-file.txt", "SOME CONTENT");
fileSystem.File.WriteAllText("my-third-file.txt", "some other content");

await That(fileSystem).HasFile("my-file.txt").WithContent().SameAs("my-other-file.txt").IgnoringCase();
await That(fileSystem).HasFile("my-file.txt").WithContent().NotSameAs("my-third-file.txt");

…and against the file's timestamps. .Within(tolerance) widens the comparison to a window:

await That(fileSystem).HasFile("my-file.txt").WithCreationTime(DateTime.Now).Within(1.Second());
await That(fileSystem).HasFile("my-file.txt").WithLastAccessTime(DateTime.Now).Within(1.Second());
await That(fileSystem).HasFile("my-file.txt").WithLastWriteTime(DateTime.Now).Within(1.Second());

Directory chain

HasDirectory(path) exposes sub-collections:

IFileSystem fileSystem = new MockFileSystem();
fileSystem.Directory.CreateDirectory("foo/bar1");
fileSystem.Directory.CreateDirectory("foo/bar2/baz");
fileSystem.File.WriteAllText("foo/bar/my-file.txt", "some content");

await That(fileSystem).HasDirectory("foo").WithDirectories(d => d.HasCount().EqualTo(2));
await That(fileSystem).HasDirectory("foo/bar").WithFiles(f => f
    .All().ComplyWith(x => x.HasContent("SOME CONTENT").IgnoringCase()));

Bridging to IFileInfo / IDirectoryInfo / IDriveInfo via .Which

HasFile, HasDirectory and HasDrive each expose a .Which property that returns the resolved IFileInfo / IDirectoryInfo / IDriveInfo so the subject-level assertions below light up directly in the chain:

await That(fileSystem).HasFile("my-file.txt").Which.HasLength(12).And.HasContent("some content");
await That(fileSystem).HasDirectory("logs").Which.IsEmpty();
await That(fileSystem).HasDrive("D:\\").Which.IsReady().And.HasDriveFormat("NTFS");

File (IFileInfo)

IFileInfo fileInfo = fileSystem.FileInfo.New("my-file.txt");

await That(fileInfo).Exists();
await That(fileInfo).DoesNotExist();

await That(fileInfo).HasName("my-file.txt");
await That(fileInfo).HasExtension(".txt");
await That(fileInfo).HasLength(12);
await That(fileInfo).HasContent("some content");
await That(fileInfo).HasContent(new byte[] { 0x73, 0x6F, 0x6D, 0x65 });

await That(fileInfo).IsReadOnly();
await That(fileInfo).IsNotReadOnly();

await That(fileInfo).HasAttribute(FileAttributes.ReadOnly);
await That(fileInfo).DoesNotHaveAttribute(FileAttributes.Hidden);

await That(fileInfo).HasCreationTime(DateTime.Now).Within(1.Second());
await That(fileInfo).HasLastAccessTime(DateTime.Now).Within(1.Second());
await That(fileInfo).HasLastWriteTime(DateTime.Now).Within(1.Second());

HasAttribute / DoesNotHaveAttribute use flag containment, so FileAttributes.ReadOnly | FileAttributes.Hidden satisfies HasAttribute(FileAttributes.ReadOnly). The empty / default value is rejected with an ArgumentException to avoid silent passes.

On .NET 10 or later, WhoseParent switches the subject to the containing directory so the directory-level assertions can be reused:

await That(fileInfo).WhoseParent.HasName("docs").And.IsNotEmpty();

Directory (IDirectoryInfo)

IDirectoryInfo dirInfo = fileSystem.DirectoryInfo.New("foo");

await That(dirInfo).Exists();
await That(dirInfo).DoesNotExist();

await That(dirInfo).HasName("foo");

await That(dirInfo).IsEmpty();
await That(dirInfo).IsNotEmpty();

await That(dirInfo).HasFile("bar/my-file.txt");
await That(dirInfo).DoesNotHaveFile("bar/missing.txt");
await That(dirInfo).HasDirectory("bar").Which.HasFile("my-file.txt");
await That(dirInfo).DoesNotHaveDirectory("not-here");

await That(dirInfo).HasAttribute(FileAttributes.Directory);
await That(dirInfo).DoesNotHaveAttribute(FileAttributes.Hidden);

await That(dirInfo).HasCreationTime(DateTime.Now).Within(1.Second());
await That(dirInfo).HasLastAccessTime(DateTime.Now).Within(1.Second());
await That(dirInfo).HasLastWriteTime(DateTime.Now).Within(1.Second());

HasFile / HasDirectory on IDirectoryInfo return the same chain results as the file-system-level versions, so .WithContent(...), .WithLastWriteTime(...), .Which, etc. all work as well: the path is resolved relative to the directory.

On .NET 10 or later, WhoseParent switches to the parent directory:

await That(dirInfo).WhoseParent.HasName("…");

Drive (IDriveInfo)

MockFileSystem fileSystem = new(o => o.SimulatingOperatingSystem(SimulationMode.Windows));
fileSystem.WithDrive("D:", d => d.SetTotalSize(2048));

IDriveInfo driveInfo = fileSystem.DriveInfo.New("D:");

await That(driveInfo).HasAvailableFreeSpace(2048);
await That(driveInfo).HasTotalSize(2048).And.HasTotalFreeSpace(2048);
await That(driveInfo).HasDriveFormat("NTFS");
await That(driveInfo).HasDriveType(DriveType.Fixed);
await That(driveInfo).HasName(driveInfo.Name).And.HasVolumeLabel(driveInfo.VolumeLabel);
await That(driveInfo).IsReady();

Drives are matched by name (case-insensitive) against IFileSystem.DriveInfo.GetDrives(). UNC drives, which do not appear in GetDrives(), are not supported by HasDrive.

File version info (IFileVersionInfo)

IFileVersionInfo instances obtained via MockFileSystem.FileVersionInfo.GetVersionInfo can be asserted directly. The values come from MockFileSystem.WithFileVersionInfo(glob, builder):

MockFileSystem fileSystem = new();
fileSystem.WithFileVersionInfo("*.dll", v => v
    .SetCompanyName("Acme")
    .SetProductName("Anvil")
    .SetFileVersion("1.2.3.4")
    .SetIsDebug(true));
fileSystem.File.WriteAllText("Acme.dll", "");

IFileVersionInfo info = fileSystem.FileVersionInfo.GetVersionInfo("Acme.dll");

await That(info).HasCompanyName("Acme").And.HasProductName("Anvil");
await That(info).HasFileVersion("1.2.3.4").And.HasFileMajorPart(1);
await That(info).IsDebug().And.IsNotPreRelease();

Dedicated assertions cover every IFileVersionInfo property — strings via Has…(string), the integer version parts via Has…(int) and the booleans as Is…() / IsNot…() pairs.

Property	Assertion
Comments	HasComments(string)
CompanyName	HasCompanyName(string)
FileDescription	HasFileDescription(string)
FileName	HasFileName(string)
FileVersion	HasFileVersion(string)
InternalName	HasInternalName(string)
Language	HasLanguage(string)
LegalCopyright	HasLegalCopyright(string)
LegalTrademarks	HasLegalTrademarks(string)
OriginalFilename	HasOriginalFilename(string)
PrivateBuild	HasPrivateBuild(string)
ProductName	HasProductName(string)
ProductVersion	HasProductVersion(string)
SpecialBuild	HasSpecialBuild(string)
FileBuildPart	HasFileBuildPart(int)
FileMajorPart	HasFileMajorPart(int)
FileMinorPart	HasFileMinorPart(int)
FilePrivatePart	HasFilePrivatePart(int)
ProductBuildPart	HasProductBuildPart(int)
ProductMajorPart	HasProductMajorPart(int)
ProductMinorPart	HasProductMinorPart(int)
ProductPrivatePart	HasProductPrivatePart(int)
IsDebug	IsDebug() / IsNotDebug()
IsPatched	IsPatched() / IsNotPatched()
IsPreRelease	IsPreRelease() / IsNotPreRelease()
IsPrivateBuild	IsPrivateBuild() / IsNotPrivateBuild()
IsSpecialBuild	IsSpecialBuild() / IsNotSpecialBuild()

File-system notifications

A MockFileSystem raises notifications when files or directories change. Run the code under test, then assert against the notifications it produced:

MockFileSystem fileSystem = new();
fileSystem.File.WriteAllText("my-file.txt", "some content");

await That(fileSystem).TriggeredNotification();
await That(fileSystem).TriggeredNotification(c => c.Name == "my-file.txt");

.Within(timeout) (default 30 s) lets the assertion wait for asynchronous notifications. If a matching notification already fired, the assertion completes synchronously; otherwise it waits up to the timeout for a late arrival:

_ = Task.Run(() => fileSystem.File.WriteAllText("foo.txt", "x"));
await That(fileSystem).TriggeredNotification().Within(100.Milliseconds());

DidNotTriggerNotification mirrors the same shapes and short-circuits as soon as a matching notification is observed:

await That(fileSystem).DidNotTriggerNotification().Within(100.Milliseconds());
await That(fileSystem).DidNotTriggerNotification(c => c.Name == "secret.txt");

Both accept a Quantifier (AtLeast, AtMost, Exactly, Between, Never, Once) so you can assert how often the notification fires, and a .Which(c => …) callback that composes the per-notification expectations from ChangeDescription:

fileSystem.File.WriteAllText("a.txt", "x");
fileSystem.File.WriteAllText("b.txt", "y");

await That(fileSystem).TriggeredNotification(c => c.ChangeType == WatcherChangeTypes.Created)
    .Exactly(2.Times());

await That(fileSystem)
    .TriggeredNotification()
    .Which(c => c.HasName("a.txt").And.HasChangeType(WatcherChangeTypes.Created))
    .Exactly(1.Times());

Replay of historical notifications relies on the MockFileSystem notification history. Disable it via new MockFileSystem(o => o.WithoutNotificationHistory()) only if you don't use these assertions: they throw against a history-disabled file system.

Watcher events (IFileSystemWatcher)

An individual IFileSystemWatcher can also be the subject. The watcher must come from a MockFileSystem, and EnableRaisingEvents must be true for any event to be observed. Only events fired on this specific watcher count; events fired on other watchers of the same MockFileSystem are ignored.

MockFileSystem fileSystem = new();
using IFileSystemWatcher watcher = fileSystem.FileSystemWatcher.New("/");
watcher.EnableRaisingEvents = true;
fileSystem.File.WriteAllText("my-file.txt", "some content");

await That(watcher).Triggered();
await That(watcher).Triggered(c => c.Name == "my-file.txt");

await That(watcher).DidNotTrigger().Within(100.Milliseconds());
await That(watcher).DidNotTrigger(c => c.Name == "secret.txt");

Triggered and DidNotTrigger share the same shape as the notification assertions: a Quantifier (AtLeast, AtMost, Exactly, Between, Never, Once), a .Within(timeout) (default 30 s), and a .Which(c => …) callback that composes the per-change expectations from ChangeDescription:

await That(watcher)
    .Triggered()
    .Which(c => c.HasName("my-file.txt").And.HasChangeType(WatcherChangeTypes.Created))
    .Exactly(1.Times());

ChangeDescription

Individual ChangeDescription instances can be asserted directly:

await That(change).HasChangeType(WatcherChangeTypes.Created);
await That(change).DoesNotHaveChangeType(WatcherChangeTypes.Deleted);

await That(change).HasFileSystemType(FileSystemTypes.File);
await That(change).HasNotifyFilters(NotifyFilters.LastWrite);

await That(change).HasName("my-file.txt").And.HasPath("/abs/my-file.txt");
await That(renamedChange).HasOldName("old.txt").And.HasOldPath("/abs/old.txt");

HasChangeType, HasFileSystemType and HasNotifyFilters use flag containment (so a LastWrite | FileName change satisfies HasNotifyFilters(NotifyFilters.LastWrite)); the empty / default value is rejected with an ArgumentException to avoid silent passes.

Recorded calls (IFileSystemStatistics)

MockFileSystem.Statistics records every method call and property access on the mock. .Recorded() exposes a fluent mirror over these recordings, so you can assert what the system under test actually called:

MockFileSystem fileSystem = new();
fileSystem.File.WriteAllText("foo.txt", "x");

await That(fileSystem.Statistics).Recorded().File.WriteAllText().Once();
await That(fileSystem.Statistics).Recorded().File.WriteAllText(path: p => p == "foo.txt").Once();

The mirror has one entry per IFileSystem member (.File, .Directory, .FileInfo[path], .DirectoryInfo[path], .DriveInfo, .FileStream, .FileSystemWatcher, .FileVersionInfo, .Path), with one method per underlying API and an indexer ([path]) for per-instance buckets. Every result inherits the count vocabulary (Once, Twice, Never, Exactly, AtLeast, AtMost, Between, …).

Property reads and writes are recorded with .Get() / .Set():

fileSystem.FileInfo.New("foo.txt").IsReadOnly = true;

await That(fileSystem.Statistics).Recorded().FileInfo["foo.txt"].IsReadOnly.Set().Once();
await That(fileSystem.Statistics).Recorded().DirectoryInfo["foo"].Exists.Get().AtLeast().Once();

Each parameter on a mirror method is an optional Func<T, bool> predicate matched positionally against the recorded argument:

• Supplying no predicate (or null) skips that position and matches every overload, so .File.Open() counts all Open invocations regardless of arity.
• A predicate whose position exceeds an overload's arity excludes that overload, so filtering recursive on Directory.Delete only matches the two-argument overload.
• A predicate whose type differs from the recorded type at that position silently excludes that overload, so filtering searchOption on Directory.EnumerateDirectories never matches the EnumerationOptions overload.

A handful of methods can't be filtered fully through this positional model because two overloads place different types at the same recording position (File.Open / FileInfo.Open with FileStreamOptions, FileSystemWatcher.WaitForChanged with TimeSpan).

Timer (ITimerMock)

A MockTimeSystem exposes timers as ITimerMock. You can assert how often the timer callback was executed without blocking the test thread:

MockTimeSystem timeSystem = new();
ITimerMock timer = (ITimerMock)timeSystem.Timer.New(
    _ => { }, null, TimeSpan.Zero, TimeSpan.FromMilliseconds(10));

await That(timer).Executed(3.Times()).Within(5.Seconds());

Executed() accepts a Quantifier (AtLeast, AtMost, Exactly, Between, Never, Once) and exposes .Within(timeout) for asynchronous execution. The assertion polls ITimerMock.ExecutionCount until the quantifier is satisfied or the timeout expires (30 seconds by default).

await That(timer).Executed().AtLeast(2.Times()).Within(100.Milliseconds());