feat: Analyzer Phase 4 severity updates + BWFC025 non-serializable ViewState

src/BlazorWebFormsComponents.Analyzers.Test/AllAnalyzersIntegrationTests.cs

@@ -41,6 +41,7 @@ public class AllAnalyzersIntegrationTests
         "BWFC021", // FindControlUsageAnalyzer
         "BWFC022", // PageClientScriptUsageAnalyzer
         "BWFC023", // IPostBackEventHandlerUsageAnalyzer
+        "BWFC025", // NonSerializableViewStateAnalyzer
     };
 
     #region ID Registration and Uniqueness

src/BlazorWebFormsComponents.Analyzers.Test/IsPostBackUsageAnalyzerTests.cs

@@ -27,7 +27,7 @@ protected void DoInit() { }
 ";
 
     private static DiagnosticResult ExpectBWFC003(string memberName) =>
-        new DiagnosticResult(IsPostBackUsageAnalyzer.DiagnosticId, DiagnosticSeverity.Warning)
+        new DiagnosticResult(IsPostBackUsageAnalyzer.DiagnosticId, DiagnosticSeverity.Info)
             .WithArguments(memberName);
 
     #region Positive cases — BWFC003 SHOULD fire

src/BlazorWebFormsComponents.Analyzers.Test/NonSerializableViewStateAnalyzerTests.cs

@@ -0,0 +1,217 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Testing;
+
+namespace BlazorWebFormsComponents.Analyzers.Test;
+
+using AnalyzerTest = Microsoft.CodeAnalysis.CSharp.Testing.CSharpAnalyzerTest<
+    NonSerializableViewStateAnalyzer,
+    DefaultVerifier>;
+
+/// <summary>
+/// Tests for BWFC025: ViewState value may not be JSON-serializable.
+/// </summary>
+public class NonSerializableViewStateAnalyzerTests
+{
+    private const string StubSource = @"
+using System;
+using System.Collections.Generic;
+
+public class ViewStateDictionary : Dictionary<string, object>
+{
+    public void Set<T>(string key, T value) { this[key] = value; }
+}
+
+public class PageBase
+{
+    public ViewStateDictionary ViewState { get; } = new ViewStateDictionary();
+}
+";
+
+    private static DiagnosticResult ExpectBWFC025(string typeName) =>
+        new DiagnosticResult(NonSerializableViewStateAnalyzer.DiagnosticId, DiagnosticSeverity.Warning)
+            .WithArguments(typeName);
+
+    #region Negative cases — BWFC025 should NOT fire
+
+    [Fact]
+    public async Task ViewState_AssignString_NoDiagnostic()
+    {
+        var source = @"
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        ViewState[""key""] = ""hello"";
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ViewState_AssignInt_NoDiagnostic()
+    {
+        var source = @"
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        ViewState[""key""] = 42;
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ViewState_AssignBool_NoDiagnostic()
+    {
+        var source = @"
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        ViewState[""key""] = true;
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ViewState_SetGeneric_String_NoDiagnostic()
+    {
+        var source = @"
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        ViewState.Set<string>(""key"", ""val"");
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } }
+        };
+        await test.RunAsync();
+    }
+
+    #endregion
+
+    #region Positive cases — BWFC025 SHOULD fire
+
+    [Fact]
+    public async Task ViewState_AssignDisposable_Diagnostic()
+    {
+        var source = @"
+using System.IO;
+
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        {|#0:ViewState[""key""] = new MemoryStream()|};
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } },
+            ExpectedDiagnostics = { ExpectBWFC025("System.IO.MemoryStream").WithLocation(0) }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ViewState_AssignDataTable_Diagnostic()
+    {
+        // Use a minimal stub for DataTable since System.Data is not referenced
+        var dataStub = @"
+namespace System.Data
+{
+    public class DataTable
+    {
+        public string TableName { get; set; }
+    }
+}
+";
+
+        var source = @"
+using System.Data;
+
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        {|#0:ViewState[""key""] = new DataTable()|};
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource, dataStub } },
+            ExpectedDiagnostics = { ExpectBWFC025("System.Data.DataTable").WithLocation(0) }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ViewState_AssignDelegate_Diagnostic()
+    {
+        var source = @"
+using System;
+
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        Action callback = () => { };
+        {|#0:ViewState[""key""] = callback|};
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } },
+            ExpectedDiagnostics = { ExpectBWFC025("System.Action").WithLocation(0) }
+        };
+        await test.RunAsync();
+    }
+
+    [Fact]
+    public async Task ThisViewState_AssignDisposable_Diagnostic()
+    {
+        var source = @"
+using System.IO;
+
+public class MyPage : PageBase
+{
+    public void Page_Load()
+    {
+        {|#0:this.ViewState[""key""] = new MemoryStream()|};
+    }
+}";
+
+        var test = new AnalyzerTest
+        {
+            TestState = { Sources = { source, StubSource } },
+            ExpectedDiagnostics = { ExpectBWFC025("System.IO.MemoryStream").WithLocation(0) }
+        };
+        await test.RunAsync();
+    }
+
+    #endregion
+}

src/BlazorWebFormsComponents.Analyzers.Test/ViewStateUsageAnalyzerTests.cs

@@ -27,7 +27,7 @@ public class PageBase
 ";
 
     private static DiagnosticResult ExpectBWFC002(string memberName) =>
-        new DiagnosticResult(ViewStateUsageAnalyzer.DiagnosticId, DiagnosticSeverity.Warning)
+        new DiagnosticResult(ViewStateUsageAnalyzer.DiagnosticId, DiagnosticSeverity.Info)
             .WithArguments(memberName);
 
     #region Positive cases — BWFC002 SHOULD fire

src/BlazorWebFormsComponents.Analyzers/AnalyzerReleases.Unshipped.md

@@ -3,8 +3,8 @@
 Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
 BWFC001 | Usage    | Warning  | MissingParameterAttributeAnalyzer
-BWFC002 | Usage    | Warning  | ViewStateUsageAnalyzer
-BWFC003 | Usage    | Warning  | IsPostBackUsageAnalyzer
+BWFC002 | Usage    | Info     | ViewStateUsageAnalyzer (was Warning — ViewState now works as migration shim)
+BWFC003 | Usage    | Info     | IsPostBackUsageAnalyzer (was Warning — IsPostBack now works via BWFC shim)
 BWFC004 | Usage    | Warning  | ResponseRedirectAnalyzer
 BWFC005 | Usage    | Warning  | SessionUsageAnalyzer
 BWFC010 | Usage    | Info     | RequiredAttributeAnalyzer
@@ -16,3 +16,4 @@ BWFC020 | Migration | Info     | ViewStatePropertyPatternAnalyzer
 BWFC021 | Migration | Warning  | FindControlUsageAnalyzer
 BWFC022 | Migration | Warning  | PageClientScriptUsageAnalyzer
 BWFC023 | Migration | Warning  | IPostBackEventHandlerUsageAnalyzer
+BWFC025 | Usage    | Warning  | NonSerializableViewStateAnalyzer

src/BlazorWebFormsComponents.Analyzers/IsPostBackUsageAnalyzer.cs

@@ -8,24 +8,24 @@ namespace BlazorWebFormsComponents.Analyzers
 {
     /// <summary>
     /// Analyzer that detects IsPostBack and Page.IsPostBack usage patterns.
-    /// Blazor uses component lifecycle instead of the postback model.
+    /// IsPostBack works via the BWFC shim; suggests Blazor lifecycle methods for new code.
     /// </summary>
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
     public class IsPostBackUsageAnalyzer : DiagnosticAnalyzer
     {
         public const string DiagnosticId = "BWFC003";
 
         private static readonly LocalizableString Title = "IsPostBack usage detected";
-        private static readonly LocalizableString MessageFormat = "'{0}' checks IsPostBack \u2014 Blazor doesn't have postbacks. Use lifecycle methods (OnInitialized, OnParametersSet) instead.";
-        private static readonly LocalizableString Description = "Flags IsPostBack and Page.IsPostBack checks. Blazor uses component lifecycle instead of postback model.";
+        private static readonly LocalizableString MessageFormat = "'{0}' checks IsPostBack \u2014 this works via the BWFC shim (SSR: checks HTTP POST, Interactive: tracks initialization). For new code, prefer OnInitialized lifecycle.";
+        private static readonly LocalizableString Description = "Flags IsPostBack and Page.IsPostBack checks. IsPostBack works via the BWFC shim during migration; prefer Blazor lifecycle methods for new code.";
         private const string Category = "Usage";
 
         private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(
             DiagnosticId,
             Title,
             MessageFormat,
             Category,
-            DiagnosticSeverity.Warning,
+            DiagnosticSeverity.Info,
             isEnabledByDefault: true,
             description: Description);