refactor: fix brittle EventTests (#599)

The `FileSystemWatcher.EventTests` sometimes fail, due to race-condition. Therefore make the following changes:
- Continually make the triggering changes in a background task, until the `CancellationToken` is cancelled at the end of the test
- Add and listen to separate triggers for when the triggering change was made and when the change was detected in the callback
- Make tests synchronous
- Add class `TestBase` with common timeout settings and use them throughout the Testably.Abstractions.Tests project.

Author: vbreuss

Tests/Helpers/Testably.Abstractions.TestHelpers/FileSystemTestBase.cs

@@ -13,7 +13,7 @@ namespace Testably.Abstractions.TestHelpers;
 /// <remarks>
 ///     Important: You have to mark your class as ´partial`!
 /// </remarks>
-public abstract class FileSystemTestBase<TFileSystem>
+public abstract class FileSystemTestBase<TFileSystem> : TestBase
 	where TFileSystem : IFileSystem
 {
 	public abstract string BasePath { get; }

Tests/Helpers/Testably.Abstractions.TestHelpers/RandomSystemTestBase.cs

@@ -12,7 +12,7 @@ namespace Testably.Abstractions.TestHelpers;
 /// <remarks>
 ///     Important: You have to mark your class as ´partial`!
 /// </remarks>
-public abstract class RandomSystemTestBase<TRandomSystem>
+public abstract class RandomSystemTestBase<TRandomSystem> : TestBase
 	where TRandomSystem : IRandomSystem
 {
 	public TRandomSystem RandomSystem { get; }

Tests/Helpers/Testably.Abstractions.TestHelpers/TestBase.cs

@@ -0,0 +1,22 @@
+namespace Testably.Abstractions.TestHelpers;
+
+/// <summary>
+///     Base class for generated tests.
+/// </summary>
+public abstract class TestBase
+{
+	/// <summary>
+	///     The delay in milliseconds when wanting to ensure a timeout in the test.
+	/// </summary>
+	public const int EnsureTimeout = 500;
+
+	/// <summary>
+	///     The delay in milliseconds when expecting a success in the test.
+	/// </summary>
+	public const int ExpectSuccess = 30000;
+
+	/// <summary>
+	///     The delay in milliseconds when expecting a timeout in the test.
+	/// </summary>
+	public const int ExpectTimeout = 30;
+}

Tests/Helpers/Testably.Abstractions.TestHelpers/TimeSystemTestBase.cs

@@ -12,7 +12,7 @@ namespace Testably.Abstractions.TestHelpers;
 /// <remarks>
 ///     Important: You have to mark your class as ´partial`!
 /// </remarks>
-public abstract class TimeSystemTestBase<TTimeSystem>
+public abstract class TimeSystemTestBase<TTimeSystem> : TestBase
 	where TTimeSystem : ITimeSystem
 {
 	public TTimeSystem TimeSystem { get; }

Tests/Testably.Abstractions.Tests/FileSystem/File/CopyTests.cs

@@ -257,7 +257,7 @@ public void Copy_ShouldCopyFileWithContent(
 
 		FileSystem.File.WriteAllText(sourceName, contents);
 
-		TimeSystem.Thread.Sleep(1000);
+		TimeSystem.Thread.Sleep(EnsureTimeout);
 
 		FileSystem.File.Copy(sourceName, destinationName);
 		FileSystem.Should().HaveFile(sourceName)

Tests/Testably.Abstractions.Tests/FileSystem/FileInfo/CopyToTests.cs

@@ -112,7 +112,7 @@ public void CopyTo_ShouldCopyFileWithContent(
 		FileSystem.File.WriteAllText(sourceName, contents);
 		IFileInfo sut = FileSystem.FileInfo.New(sourceName);
 
-		TimeSystem.Thread.Sleep(1000);
+		TimeSystem.Thread.Sleep(EnsureTimeout);
 
 		IFileInfo result = sut.CopyTo(destinationName);
 

Tests/Testably.Abstractions.Tests/FileSystem/FileStream/ReadTests.cs

@@ -56,7 +56,7 @@ public void BeginRead_ShouldCopyContentsToBuffer(
 			}
 		}, null);
 
-		ms.Wait(30000);
+		ms.Wait(ExpectSuccess).Should().BeTrue();
 		buffer.Should().BeEquivalentTo(bytes);
 	}
 
@@ -107,7 +107,7 @@ public void EndRead_ShouldNotAdjustTimes(string path, byte[] bytes)
 				}
 			}, null);
 
-			ms.Wait(10000);
+			ms.Wait(ExpectSuccess).Should().BeTrue();
 		}
 
 		DateTime creationTime = FileSystem.File.GetCreationTimeUtc(path);
@@ -202,7 +202,7 @@ public void Read_ShouldFillBuffer(string path, byte[] bytes)
 	public async Task ReadAsync_CanReadFalse_ShouldThrowNotSupportedException(
 		string path, byte[] bytes)
 	{
-		using CancellationTokenSource cts = new(30000);
+		using CancellationTokenSource cts = new(ExpectSuccess);
 		byte[] buffer = new byte[bytes.Length];
 		await FileSystem.File.WriteAllBytesAsync(path, bytes, cts.Token);
 		Exception? exception;
@@ -228,7 +228,7 @@ public async Task ReadAsync_CanReadFalse_ShouldThrowNotSupportedException(
 	public async Task ReadAsync_Memory_CanReadFalse_ShouldThrowNotSupportedException(
 		string path, byte[] bytes)
 	{
-		using CancellationTokenSource cts = new(30000);
+		using CancellationTokenSource cts = new(ExpectSuccess);
 		byte[] buffer = new byte[bytes.Length];
 		await FileSystem.File.WriteAllBytesAsync(path, bytes, cts.Token);
 		Exception? exception;
@@ -253,7 +253,7 @@ public async Task ReadAsync_Memory_CanReadFalse_ShouldThrowNotSupportedException
 	[AutoData]
 	public async Task ReadAsync_ShouldFillBuffer(string path, byte[] bytes)
 	{
-		using CancellationTokenSource cts = new(30000);
+		using CancellationTokenSource cts = new(ExpectSuccess);
 		byte[] buffer = new byte[bytes.Length];
 		await FileSystem.File.WriteAllBytesAsync(path, bytes, cts.Token);
 		await using FileSystemStream stream = FileSystem.File.OpenRead(path);

Tests/Testably.Abstractions.Tests/FileSystem/FileStream/WriteTests.cs

@@ -57,7 +57,7 @@ public void BeginWrite_ShouldCopyContentsToFile(
 				}
 			}, null);
 
-			ms.Wait(30000);
+			ms.Wait(ExpectSuccess).Should().BeTrue();
 		}
 
 		FileSystem.Should().HaveFile(path)
@@ -108,7 +108,7 @@ public void EndWrite_ShouldAdjustTimes(string path, byte[] bytes)
 				}
 			}, null);
 
-			ms.Wait(10000);
+			ms.Wait(ExpectSuccess).Should().BeTrue();
 		}
 
 		DateTime creationTime = FileSystem.File.GetCreationTimeUtc(path);
@@ -210,7 +210,7 @@ public void Write_ShouldFillBuffer(string path, byte[] bytes)
 	public async Task WriteAsync_CanWriteFalse_ShouldThrowNotSupportedException(
 		string path, byte[] bytes)
 	{
-		using CancellationTokenSource cts = new(30000);
+		using CancellationTokenSource cts = new(ExpectSuccess);
 		byte[] buffer = new byte[bytes.Length];
 		await FileSystem.File.WriteAllBytesAsync(path, bytes, cts.Token);
 		Exception? exception;
@@ -236,7 +236,7 @@ public async Task WriteAsync_CanWriteFalse_ShouldThrowNotSupportedException(
 	[AutoData]
 	public async Task WriteAsync_ShouldFillBuffer(string path, byte[] bytes)
 	{
-		using CancellationTokenSource cts = new(30000);
+		using CancellationTokenSource cts = new(ExpectSuccess);
 
 		await using (FileSystemStream stream = FileSystem.File.Create(path))
 		{

Tests/Testably.Abstractions.Tests/FileSystem/FileSystemWatcher/EnableRaisingEventsTests.cs

@@ -30,13 +30,13 @@ public void EnableRaisingEvents_SetToFalse_ShouldStop(string path1, string path2
 		};
 		fileSystemWatcher.EnableRaisingEvents = true;
 		FileSystem.Directory.Delete(path1);
-		ms.Wait(10000).Should().BeTrue();
+		ms.Wait(ExpectSuccess).Should().BeTrue();
 		ms.Reset();
 
 		fileSystemWatcher.EnableRaisingEvents = false;
 
 		FileSystem.Directory.Delete(path2);
-		ms.Wait(30).Should().BeFalse();
+		ms.Wait(ExpectTimeout).Should().BeFalse();
 	}
 
 	[SkippableTheory]
@@ -62,6 +62,6 @@ public void EnableRaisingEvents_ShouldBeInitializedAsFalse(string path)
 
 		FileSystem.Directory.Delete(path);
 
-		ms.Wait(30).Should().BeFalse();
+		ms.Wait(ExpectTimeout).Should().BeFalse();
 	}
 }