Checkpoint.

Author: electricessence

ReadWriteHelper/ReadWriteHelper.cs

@@ -312,7 +312,7 @@ private bool TryExecute<T>(
 		internal ContextHandler(ReadWriteHelper<TContext> helper, TContext context)
 		{
 			Helper = helper;
-			Context = context;
+			Context = context ?? throw new ArgumentNullException(nameof(context));
 		}
 
 		/// <inheritdoc />

source/Documentation.xml

@@ -48,6 +48,29 @@ public Lock(
 		LockHeld = true;
 	}
 
+	/// <summary>
+	/// Returns true if <paramref name="syncObject"/> is valid for locking.
+	/// </summary>
+	public static bool IsValidSyncObject(object? syncObject)
+		=> syncObject switch // Avoid the lock object being immutable...
+		{
+			null or string or Type or ValueType => false,
+			_ => true,
+		};
+
+	/// <summary>
+	/// Throws an exception if <paramref name="syncObject"/> is not valid for locking.
+	/// </summary>
+	/// <exception cref="ArgumentNullException">If <paramref name="syncObject"/> is null.</exception>
+	/// <exception cref="ArgumentException">If <paramref name="syncObject"/> is not valid for locking.</exception>
+	public static void AssertSyncObject(object? syncObject)
+	{
+		if (syncObject is null)
+			throw new ArgumentNullException(nameof(syncObject));
+		if (syncObject is string or Type or ValueType)
+			throw new ArgumentException($"Is not valid sync object. Invalid type: ({syncObject.GetType()})", nameof(syncObject));
+	}
+
 	/// <inheritdoc cref="ILock.LockHeld"/>
 	[ExcludeFromCodeCoverage]
 	public static implicit operator bool(Lock monitor) => monitor.LockHeld;

source/Locks/Lock.cs

@@ -19,7 +19,7 @@
 		<PackageProjectUrl>https://github.com/Open-NET-Libraries/Open.Threading.ReadWrite/</PackageProjectUrl>
 		<RepositoryUrl>https://github.com/Open-NET-Libraries/Open.Threading.ReadWrite/</RepositoryUrl>
 		<RepositoryType>git</RepositoryType>
-		<Version>2.0.0-preview2</Version>
+		<Version>2.0.0-preview3</Version>
 		<PackageReleaseNotes></PackageReleaseNotes>
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<PublishRepositoryUrl>true</PublishRepositoryUrl>

source/Open.Threading.ReadWrite.csproj

@@ -31,4 +31,27 @@ public void BasicTests()
 			sync.LockHeld.Should().BeTrue();
 		}
 	}
+
+	struct Test { }
+
+	[Theory]
+	[InlineData(null)]
+	[InlineData(true)]
+	[InlineData(false)]
+	[InlineData("hello")]
+	[InlineData(0)]
+	[InlineData(1)]
+	public void InvalidSyncObjectTests(object? syncObject)
+	{
+		Lock.IsValidSyncObject(syncObject).Should().BeFalse();
+		if(syncObject is null)
+			Assert.Throws<ArgumentNullException>(() => Lock.AssertSyncObject(syncObject));
+		else
+			Assert.Throws<ArgumentException>(() => Lock.AssertSyncObject(syncObject));
+	}
+
+	[Fact]
+	public void StructSyncObjectTests()
+		=> InvalidSyncObjectTests(new Test());
+
 }