CanBeEqual: Add special case for Uri.Equals(string)

src/nunit.analyzers.tests/EqualToIncompatibleTypes/EqualToIncompatibleTypesAnalyzerTests.cs

@@ -951,5 +951,34 @@ public void AnalyzeWhenThrowsWithTypeConstraintIsUsedWithDifferentType(string co
 
             RoslynAssert.Diagnostics(analyzer, testCode);
         }
+
+        [Test]
+        public void AnalyzeWhenComparingUriWithString()
+        {
+            // Uri.Equals(object? comparand) has code that checks if comparand is a string.
+            // There is no separate overload for Uri.Equals(string?) to check for.
+            var testCode = TestUtility.WrapInTestMethod(@"
+                const string testString = ""test"";
+                Uri testUri = new Uri(""test"", UriKind.Relative);
+
+                Assert.That(testUri, Is.EqualTo(testString));
+            ");
+
+            RoslynAssert.Valid(analyzer, testCode);
+        }
+
+        [Test]
+        public void AnalyzeWhenComparingStringWithUri()
+        {
+            // string.Equals(Uri) always fails
+            var testCode = TestUtility.WrapInTestMethod(@"
+                const string testString = ""test"";
+                Uri testUri = new Uri(""test"", UriKind.Relative);
+
+                Assert.That(testString, Is.EqualTo(↓testUri));
+            ");
+
+            RoslynAssert.Diagnostics(analyzer, testCode);
+        }
     }
 }

src/nunit.analyzers.tests/Helpers/NUnitEqualityComparerHelperTests.cs

@@ -213,6 +213,21 @@ public void TrueForArrayWithElementErrorType()
             AssertThatCommutativeEqual(leftTypeSymbol, rightTypeSymbol, compilation, Is.True);
         }
 
+        [Test]
+        public void UriCanEqualStringButStringCanNotEqualUri()
+        {
+            var compilation = TestHelpers.CreateCompilation();
+
+            var stringSymbol = compilation.GetSpecialType(SpecialType.System_String);
+            var uriSymbol = compilation.GetTypeByMetadataName("System.Uri");
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(NUnitEqualityComparerHelper.CanBeEqual(uriSymbol, stringSymbol, compilation), Is.True);
+                Assert.That(NUnitEqualityComparerHelper.CanBeEqual(stringSymbol, uriSymbol, compilation), Is.False);
+            });
+        }
+
         private static void AssertThatCommutativeEqual(ITypeSymbol? leftTypeSymbol, ITypeSymbol? rightTypeSymbol, Compilation compilation, Constraint constraint)
         {
             Assert.Multiple(() =>

src/nunit.analyzers/Helpers/NUnitEqualityComparerHelper.cs

@@ -100,6 +100,10 @@ public static bool CanBeEqual(
                     return CanBeEqual(actualKeyType, expectedKeyType, compilation, checkedTypes)
                         && CanBeEqual(actualValueType, expectedValueType, compilation, checkedTypes);
                 }
+
+                // Uri.Equals(string) works, but not string.Equals(Uri)
+                if (IsUri(actualFullName) && expectedType.SpecialType == SpecialType.System_String)
+                    return true;
             }
 
             // IEnumerables
@@ -182,6 +186,11 @@ private static bool IsTuple(string fullName)
             return fullName.StartsWith("System.Tuple`", StringComparison.Ordinal);
         }
 
+        private static bool IsUri(string fullName)
+        {
+            return fullName.Equals("System.Uri", StringComparison.Ordinal);
+        }
+
         private static bool IsIEquatable(ITypeSymbol typeSymbol, ITypeSymbol equatableTypeArguments)
         {
             return typeSymbol.AllInterfaces.Any(i => i.TypeArguments.Length == 1