add support for xunit StringAsserts Matches

src/FluentAssertions.Analyzers.Tests/GenerateCode.cs

@@ -225,6 +225,7 @@ public static string GenericIListExpressionBodyAssertion(string assertion) => Ge
         public static string XunitAssertion(string methodArguments, string assertion) => new StringBuilder()
             .AppendLine("using System;")
             .AppendLine("using System.Collections.Generic;")
+            .AppendLine("using System.Text.RegularExpressions;")
             .AppendLine("using FluentAssertions;")
             .AppendLine("using FluentAssertions.Extensions;")
             .AppendLine("using Xunit;")

src/FluentAssertions.Analyzers.Tests/Tips/XunitTests.cs

@@ -368,6 +368,33 @@ public void AssertStringDoesNotContain_TestAnalyzer(string assertion) =>
         public void AssertStringDoesNotContain_TestCodeFix(string oldAssertion, string newAssertion)
             => VerifyCSharpFix<AssertDoesNotContainCodeFix, AssertDoesNotContainAnalyzer>("string actual, string expected", oldAssertion, newAssertion);
 
+        [DataTestMethod]
+        [DataRow("Assert.Matches(expectedRegexPattern, actual);")]
+        [Implemented]
+        public void AssertStringMatches_String_TestAnalyzer(string assertion) =>
+            VerifyCSharpDiagnostic<AssertMatchesAnalyzer>("string actual, string expectedRegexPattern", assertion);
+
+        [DataTestMethod]
+        [DataRow(
+            /* oldAssertion: */ "Assert.Matches(expectedRegexPattern, actual);",
+            /* newAssertion: */ "actual.Should().MatchRegex(expectedRegexPattern);")]
+        [Implemented]
+        public void AssertStringMatches_String_TestCodeFix(string oldAssertion, string newAssertion)
+            => VerifyCSharpFix<AssertMatchesCodeFix, AssertMatchesAnalyzer>("string actual, string expectedRegexPattern", oldAssertion, newAssertion);
+
+        [DataTestMethod]
+        [DataRow("Assert.Matches(expectedRegex, actual);")]
+        [Implemented]
+        public void AssertStringMatches_Regex_TestAnalyzer(string assertion) =>
+            VerifyCSharpDiagnostic<AssertMatchesAnalyzer>("string actual, Regex expectedRegex", assertion);
+
+        [DataTestMethod]
+        [DataRow(
+            /* oldAssertion: */ "Assert.Matches(expectedRegex, actual);",
+            /* newAssertion: */ "actual.Should().MatchRegex(expectedRegex);")]
+        [Implemented]
+        public void AssertStringMatches_Regex_TestCodeFix(string oldAssertion, string newAssertion)
+            => VerifyCSharpFix<AssertMatchesCodeFix, AssertMatchesAnalyzer>("string actual, Regex expectedRegex", oldAssertion, newAssertion);
 
         private void VerifyCSharpDiagnostic<TDiagnosticAnalyzer>(string methodArguments, string assertion) where TDiagnosticAnalyzer : Microsoft.CodeAnalysis.Diagnostics.DiagnosticAnalyzer, new()
         {
@@ -383,7 +410,7 @@ public void AssertStringDoesNotContain_TestCodeFix(string oldAssertion, string n
                 Message = message,
                 Locations = new DiagnosticResultLocation[]
                 {
-                    new("Test0.cs", 13, 13)
+                    new("Test0.cs", 14, 13)
                 },
                 Severity = DiagnosticSeverity.Info
             });

src/FluentAssertions.Analyzers/Constants.cs

@@ -131,6 +131,7 @@ public static class Xunit
                 public const string AssertNotNull = $"{DiagnosticProperties.IdPrefix}0709";
                 public const string AssertContains = $"{DiagnosticProperties.IdPrefix}0710";
                 public const string AssertDoesNotContain = $"{DiagnosticProperties.IdPrefix}0711";
+                public const string AssertMatches = $"{DiagnosticProperties.IdPrefix}0712";
             }
         }
 

src/FluentAssertions.Analyzers/Tips/Xunit/AssertMatches.cs

@@ -0,0 +1,58 @@
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Composition;
+using FluentAssertions.Analyzers.Utilities;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace FluentAssertions.Analyzers.Xunit;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public class AssertMatchesAnalyzer : XunitAnalyzer
+{
+    public const string DiagnosticId = Constants.Tips.Xunit.AssertMatches;
+    public const string Category = Constants.Tips.Category;
+
+    public const string Message = "Use .Should().MatchRegex()";
+
+    protected override DiagnosticDescriptor Rule => new(DiagnosticId, Title, Message, Category, DiagnosticSeverity.Info, true);
+
+    protected override IEnumerable<FluentAssertionsCSharpSyntaxVisitor> Visitors => new FluentAssertionsCSharpSyntaxVisitor[]
+    {
+        new AssertMatchesStringSyntaxVisitor()
+    };
+
+    //public static void Matches(string expectedRegexPattern, string? actualString)
+    //public static void Matches(Regex expectedRegex, string? actualString)
+    public class AssertMatchesStringSyntaxVisitor : FluentAssertionsCSharpSyntaxVisitor
+    {
+        public AssertMatchesStringSyntaxVisitor() : base(
+            MemberValidator.ArgumentsMatch("Matches",
+                ArgumentValidator.IsAnyType(TypeSelector.GetStringType, TypeSelector.GetRegexType),
+                ArgumentValidator.IsType(TypeSelector.GetStringType))
+        )
+        {
+        }
+    }
+}
+
+[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(AssertMatchesCodeFix)), Shared]
+public class AssertMatchesCodeFix : XunitCodeFixProvider
+{
+    public override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(AssertMatchesAnalyzer.DiagnosticId);
+
+    protected override ExpressionSyntax GetNewExpression(
+        ExpressionSyntax expression,
+        FluentAssertionsDiagnosticProperties properties)
+    {
+        switch (properties.VisitorName)
+        {
+            case nameof(AssertMatchesAnalyzer.AssertMatchesStringSyntaxVisitor):
+                return RenameMethodAndReorderActualExpectedAndReplaceWithSubjectShould(expression, "Matches", "MatchRegex");
+            default:
+                throw new System.InvalidOperationException($"Invalid visitor name - {properties.VisitorName}");
+        }
+    }
+}

src/FluentAssertions.Analyzers/Utilities/ArgumentValidator.cs

@@ -11,6 +11,8 @@ public static ArgumentPredicate IsIdentifier()
             => (argument, semanticModel) => argument.Expression.IsKind(SyntaxKind.IdentifierName);
         public static ArgumentPredicate IsType(Func<SemanticModel, INamedTypeSymbol> typeSelector) 
             => (argument, semanticModel) => semanticModel.GetTypeInfo(argument.Expression).Type?.Equals(typeSelector(semanticModel), SymbolEqualityComparer.Default) ?? false;
+        public static ArgumentPredicate IsAnyType(params Func<SemanticModel, INamedTypeSymbol>[] typeSelectors) 
+            => (argument, semanticModel) => Array.Exists(typeSelectors, typeSelector => IsType(typeSelector)(argument, semanticModel));
         public static ArgumentPredicate IsNull() 
             => (argument, semanticModel) => argument.Expression is LiteralExpressionSyntax literal && literal.Token.IsKind(SyntaxKind.NullKeyword);
     }

src/FluentAssertions.Analyzers/Utilities/TypeSelector.cs

@@ -3,6 +3,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Globalization;
+using System.Text.RegularExpressions;
 
 namespace FluentAssertions.Analyzers.Utilities
 {
@@ -32,6 +33,9 @@ public static INamedTypeSymbol GetTimeSpanType(this SemanticModel semanticModel)
         public static INamedTypeSymbol GetStringType(this SemanticModel semanticModel)
             => GetTypeFrom(semanticModel, SpecialType.System_String);
 
+        public static INamedTypeSymbol GetRegexType(this SemanticModel semanticModel)
+            => GetTypeFrom(semanticModel, typeof(Regex));
+
         public static INamedTypeSymbol GetCultureInfoType(this SemanticModel semanticModel)
             => GetTypeFrom(semanticModel, typeof(CultureInfo));