Throw exception if base.OnInitialzed not called (Fixes #82)

Author: mrpmorris

Docs/releases.md

@@ -4,6 +4,9 @@
  * Fix for ([#84](https://github.com/mrpmorris/Fluxor/issues/84) - 
    Allow observer to unsubscribe from all subscriptions whilst executing
    the callback from a previous subscription
+ * Fix for ([#82](https://github.com/mrpmorris/Fluxor/issues/82)) -
+   Throw an informative exception when `FluxorComponent` or `FluxorLayout`
+   has been inherited and the descendant doesn't call `base.OnInitialized()`.
 
 ### New in 3.6
  * Ensure synchronous effects are executed synchronously ([#76](https://github.com/mrpmorris/fluxor/issues/76)) -

Source/Fluxor.Blazor.Web/Components/FluxorComponent.cs

@@ -44,6 +44,9 @@ protected virtual void Dispose(bool disposing)
 			{
 				if (disposing)
 				{
+					if (StateSubscription == null)
+						throw new NullReferenceException(ErrorMessages.ForgottenToCallBaseOnInitialized);
+
 					StateSubscription.Dispose();
 					ActionSubscriber?.UnsubscribeFromAllActions(this);
 				}

Source/Fluxor.Blazor.Web/Components/FluxorLayout.cs

@@ -44,6 +44,9 @@ protected virtual void Dispose(bool disposing)
 			{
 				if (disposing)
 				{
+					if (StateSubscription == null)
+						throw new NullReferenceException(ErrorMessages.ForgottenToCallBaseOnInitialized);
+
 					StateSubscription.Dispose();
 					ActionSubscriber?.UnsubscribeFromAllActions(this);
 				}

Source/Fluxor.Blazor.Web/ErrorMessages.cs

@@ -0,0 +1,8 @@
+namespace Fluxor.Blazor.Web
+{
+	internal class ErrorMessages
+	{
+		internal const string ForgottenToCallBaseOnInitialized =
+			"Have you forgotten to call base.OnInitialized() in your component?";
+	}
+}

Tests/Fluxor.Blazor.Web.UnitTests/Components/FluxorComponentTests/DisposeTests.cs

@@ -1,29 +1,58 @@
 using Fluxor.Blazor.Web.UnitTests.SupportFiles;
+using System;
 using Xunit;
 
 namespace Fluxor.Blazor.Web.UnitTests.Components.FluxorComponentTests
 {
 	public class DisposeTests
 	{
-		private readonly FluxorComponentWithStateProperties Subject;
+		private readonly FluxorComponentWithStateProperties StateSubject;
 		private readonly MockState<int> MockState1;
 		private readonly MockState<int> MockState2;
 
 		[Fact]
 		public void UnsubscribesFromStateProperties()
 		{
-			Subject.ExecuteOnInitialized();
-			Subject.Dispose();
+			StateSubject.ExecuteOnInitialized();
+			StateSubject.Dispose();
 
 			Assert.Equal(1, MockState1.UnsubscribeCount);
 			Assert.Equal(1, MockState2.UnsubscribeCount);
 		}
 
+		[Fact]
+		public void WhenBaseOnInitializedWasNotCalled_ThenThrowsNullReferenceException()
+		{
+			string errorMessage = null;
+			var component = new FluxorComponentThatOptionallyCallsBaseOnInitialized();
+			try
+			{
+				component.Test_OnInitialized();
+				component.Dispose();
+			}
+			catch (NullReferenceException e)
+			{
+				errorMessage = e.Message;
+			}
+			Assert.Equal("Have you forgotten to call base.OnInitialized() in your component?", errorMessage);
+		}
+
+		[Fact]
+		public void WhenBaseOnInitializedWasCalled_ThenDoesNotThrowAnException()
+		{
+			var component = new FluxorComponentThatOptionallyCallsBaseOnInitialized
+			{
+				CallBaseOnInitialized = true
+			};
+			component.Test_OnInitialized();
+			component.Dispose();
+		}
+
 		public DisposeTests()
 		{
 			MockState1 = new MockState<int>();
 			MockState2 = new MockState<int>();
-			Subject = new FluxorComponentWithStateProperties
+			StateSubject = new FluxorComponentWithStateProperties
 			{
 				State1 = MockState1,
 				State2 = MockState2

Tests/Fluxor.Blazor.Web.UnitTests/Components/FluxorLayoutTests/DisposeTests.cs

@@ -1,29 +1,57 @@
 using Fluxor.Blazor.Web.UnitTests.SupportFiles;
+using System;
 using Xunit;
 
 namespace Fluxor.Blazor.Web.UnitTests.Components.FluxorLayoutTests
 {
 	public class DisposeTests
 	{
-		private readonly FluxorLayoutWithStateProperties Subject;
+		private readonly FluxorLayoutWithStateProperties StateSubject;
 		private readonly MockState<int> MockState1;
 		private readonly MockState<int> MockState2;
 
 		[Fact]
 		public void UnsubscribesFromStateProperties()
 		{
-			Subject.ExecuteOnInitialized();
-			Subject.Dispose();
+			StateSubject.ExecuteOnInitialized();
+			StateSubject.Dispose();
 
 			Assert.Equal(1, MockState1.UnsubscribeCount);
 			Assert.Equal(1, MockState2.UnsubscribeCount);
 		}
 
+		[Fact]
+		public void WhenBaseOnInitializedWasNotCalled_ThenThrowsNullReferenceException()
+		{
+			string errorMessage = null;
+			var layout = new FluxorLayoutThatOptionallyCallsBaseOnInitialized();
+			try
+			{
+				layout.Test_OnInitialized();
+				layout.Dispose();
+			}
+			catch (NullReferenceException e)
+			{
+				errorMessage = e.Message;
+			}
+			Assert.Equal("Have you forgotten to call base.OnInitialized() in your component?", errorMessage);
+		}
+
+		[Fact]
+		public void WhenBaseOnInitializedWasCalled_ThenDoesNotThrowAnException()
+		{
+			var layout = new FluxorLayoutThatOptionallyCallsBaseOnInitialized
+			{
+				CallBaseOnInitialized = true
+			};
+			layout.Test_OnInitialized();
+			layout.Dispose();
+		}
 		public DisposeTests()
 		{
 			MockState1 = new MockState<int>();
 			MockState2 = new MockState<int>();
-			Subject = new FluxorLayoutWithStateProperties
+			StateSubject = new FluxorLayoutWithStateProperties
 			{
 				State1 = MockState1,
 				State2 = MockState2

Tests/Fluxor.Blazor.Web.UnitTests/SupportFiles/FluxorComponentThatOptionallyCallsBaseOnInitialized.cs

@@ -0,0 +1,17 @@
+using Fluxor.Blazor.Web.Components;
+
+namespace Fluxor.Blazor.Web.UnitTests.SupportFiles
+{
+	public class FluxorComponentThatOptionallyCallsBaseOnInitialized : FluxorComponent
+	{
+		public bool CallBaseOnInitialized;
+
+		protected override void OnInitialized()
+		{
+			if (CallBaseOnInitialized)
+				base.OnInitialized();
+		}
+
+		public void Test_OnInitialized() => OnInitialized();
+	}
+}

Tests/Fluxor.Blazor.Web.UnitTests/SupportFiles/FluxorLayoutThatOptionallyCallsBaseOnInitialized.cs

@@ -0,0 +1,17 @@
+using Fluxor.Blazor.Web.Components;
+
+namespace Fluxor.Blazor.Web.UnitTests.SupportFiles
+{
+	public class FluxorLayoutThatOptionallyCallsBaseOnInitialized : FluxorLayout
+	{
+		public bool CallBaseOnInitialized;
+
+		protected override void OnInitialized()
+		{
+			if (CallBaseOnInitialized)
+				base.OnInitialized();
+		}
+
+		public void Test_OnInitialized() => OnInitialized();
+	}
+}