diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulLinearCollectionShapeValidation.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulLinearCollectionShapeValidation.cs
index 0ad27bb6b2f8e8..13f79c7e2f2937 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulLinearCollectionShapeValidation.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulLinearCollectionShapeValidation.cs
@@ -36,14 +36,14 @@ struct MarshallerType<T>
 
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType<T>"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(LinearCollectionInRequiresCollectionMethodsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(LinearCollectionInRequiresCollectionMethodsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(1).WithArguments("MarshallerType<T>"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType<T>").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(LinearCollectionInRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(LinearCollectionInRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType<T>").WithLocation(1));
         }
 
         [Fact]
@@ -198,14 +198,14 @@ struct MarshallerType<T>
 
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType<T>"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(LinearCollectionOutRequiresCollectionMethodsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(LinearCollectionOutRequiresCollectionMethodsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(1).WithArguments("MarshallerType<T>"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType<T>").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(LinearCollectionOutRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(LinearCollectionOutRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType<T>").WithLocation(1));
         }
 
         [Fact]
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulValueShapeValidation.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulValueShapeValidation.cs
index f3e6710d8bf8c9..1fa6fbca1b3832 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulValueShapeValidation.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatefulValueShapeValidation.cs
@@ -35,12 +35,12 @@ struct MarshallerType
 
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(1).WithArguments("MarshallerType"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(1));
         }
 
         [Fact]
@@ -60,12 +60,12 @@ struct MarshallerType
 
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(1).WithArguments("MarshallerType"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(1));
         }
 
         [Fact]
@@ -108,16 +108,16 @@ struct MarshallerType
 
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(1).WithArguments("MarshallerType"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFreeRule, "MarshallerType").WithLocation(1));
         }
 
         [Fact]
@@ -215,10 +215,10 @@ struct MarshallerType
             await VerifyCS.VerifyAnalyzerAsync(
                 source,
                 VerifyCS.Diagnostic(StatefulMarshallerRequiresFreeRule).WithLocation(0).WithArguments("MarshallerType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromManagedRule).WithSeverity(DiagnosticSeverity.Info).WithLocation(0).WithArguments("MarshallerType", MarshalMode.Default, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToUnmanagedRule).WithSeverity(DiagnosticSeverity.Info).WithLocation(0).WithArguments("MarshallerType", MarshalMode.Default, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresFromUnmanagedRule).WithSeverity(DiagnosticSeverity.Info).WithLocation(0).WithArguments("MarshallerType", MarshalMode.Default, "ManagedType"),
-                VerifyCS.Diagnostic(StatefulMarshallerRequiresToManagedRule).WithSeverity(DiagnosticSeverity.Info).WithLocation(0).WithArguments("MarshallerType", MarshalMode.Default, "ManagedType"));
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromManagedRule, "MarshallerType", MarshalMode.Default, "ManagedType").WithSeverity(DiagnosticSeverity.Info).WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToUnmanagedRule, "MarshallerType", MarshalMode.Default, "ManagedType").WithSeverity(DiagnosticSeverity.Info).WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresFromUnmanagedRule, "MarshallerType", MarshalMode.Default, "ManagedType").WithSeverity(DiagnosticSeverity.Info).WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatefulMarshallerRequiresToManagedRule, "MarshallerType", MarshalMode.Default, "ManagedType").WithSeverity(DiagnosticSeverity.Info).WithLocation(0));
         }
 
         [Fact]
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessLinearCollectionShapeValidation.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessLinearCollectionShapeValidation.cs
index 5f1c0db2f4a28f..65ecd60049f429 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessLinearCollectionShapeValidation.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessLinearCollectionShapeValidation.cs
@@ -66,12 +66,12 @@ public static System.Span<T> GetUnmanagedValuesDestination(nint unmanaged, int n
             await VerifyCS.VerifyCodeFixAsync(
                 source,
                 fixedSource,
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule).WithLocation(2).WithArguments("MarshallerType<T>", MarshalMode.ElementIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionInRequiresCollectionMethodsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionInRequiresCollectionMethodsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionInRequiresCollectionMethodsRule).WithLocation(2).WithArguments("MarshallerType<T>", MarshalMode.ElementIn, "ManagedType"));
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForUnmanagedElementsRule, "MarshallerType<T>", MarshalMode.ElementIn, "ManagedType").WithLocation(2),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionInRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedIn, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionInRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedOut, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionInRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ElementIn, "ManagedType").WithLocation(2));
         }
 
         [Fact]
@@ -365,12 +365,12 @@ public static System.Span<nint> GetManagedValuesDestination(ManagedType managed)
             await VerifyCS.VerifyCodeFixAsync(
                 source,
                 fixedSource,
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule).WithLocation(2).WithArguments("MarshallerType<T>", MarshalMode.ElementOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionOutRequiresCollectionMethodsRule).WithLocation(0).WithArguments("MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionOutRequiresCollectionMethodsRule).WithLocation(1).WithArguments("MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessLinearCollectionOutRequiresCollectionMethodsRule).WithLocation(2).WithArguments("MarshallerType<T>", MarshalMode.ElementOut, "ManagedType"));
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionRequiresTwoParameterAllocateContainerForManagedElementsRule, "MarshallerType<T>", MarshalMode.ElementOut, "ManagedType").WithLocation(2),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionOutRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ManagedToUnmanagedOut, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionOutRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.UnmanagedToManagedIn, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessLinearCollectionOutRequiresCollectionMethodsRule, "MarshallerType<T>", MarshalMode.ElementOut, "ManagedType").WithLocation(2));
         }
 
         [Fact]
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessValueShapeValidation.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessValueShapeValidation.cs
index dbfe4d8d2e9e90..273982f374ded5 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessValueShapeValidation.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CustomMarshallerAttributeFixerTests_StatelessValueShapeValidation.cs
@@ -162,12 +162,12 @@ public static ManagedType ConvertToManaged(nint unmanaged)
             await VerifyCS.VerifyCodeFixAsync(
                 source,
                 fixedSource,
-                VerifyCS.Diagnostic(StatelessValueInRequiresConvertToUnmanagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessValueInRequiresConvertToUnmanagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessValueInRequiresConvertToUnmanagedRule).WithLocation(2).WithArguments("MarshallerType", MarshalMode.ElementRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessRequiresConvertToManagedRule).WithLocation(0).WithArguments("MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessRequiresConvertToManagedRule).WithLocation(1).WithArguments("MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType"),
-                VerifyCS.Diagnostic(StatelessRequiresConvertToManagedRule).WithLocation(2).WithArguments("MarshallerType", MarshalMode.ElementRef, "ManagedType"));
+                VerifyCS.DiagnosticWithArguments(StatelessValueInRequiresConvertToUnmanagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessValueInRequiresConvertToUnmanagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessValueInRequiresConvertToUnmanagedRule, "MarshallerType", MarshalMode.ElementRef, "ManagedType").WithLocation(2),
+                VerifyCS.DiagnosticWithArguments(StatelessRequiresConvertToManagedRule, "MarshallerType", MarshalMode.ManagedToUnmanagedRef, "ManagedType").WithLocation(0),
+                VerifyCS.DiagnosticWithArguments(StatelessRequiresConvertToManagedRule, "MarshallerType", MarshalMode.UnmanagedToManagedRef, "ManagedType").WithLocation(1),
+                VerifyCS.DiagnosticWithArguments(StatelessRequiresConvertToManagedRule, "MarshallerType", MarshalMode.ElementRef, "ManagedType").WithLocation(2));
         }
 
         [Fact]
diff --git a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Verifiers/CSharpCodeFixVerifier.cs b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Verifiers/CSharpCodeFixVerifier.cs
index dd30ab7a8c8a8f..172b67fa99db7c 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Verifiers/CSharpCodeFixVerifier.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/Verifiers/CSharpCodeFixVerifier.cs
@@ -5,6 +5,7 @@
 using System.Collections.Immutable;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
@@ -32,6 +33,20 @@ public static DiagnosticResult Diagnostic(string diagnosticId)
         public static DiagnosticResult Diagnostic(DiagnosticDescriptor descriptor)
             => CodeFixVerifier<TAnalyzer, TCodeFix>.Diagnostic(descriptor);
 
+        /// <summary>
+        /// Create a <see cref="DiagnosticResult"/> with the diagnostic message created with the provided arguments.
+        /// A <see cref="DiagnosticResult"/> with the <see cref="DiagnosticResult.Message"/> property set instead of just the <see cref="DiagnosticResult.MessageArguments"/> property
+        /// binds more strongly to the "correct" diagnostic as the test harness will match the diagnostic on the exact message instead of just on the message arguments.
+        /// </summary>
+        /// <param name="descriptor">The diagnostic descriptor</param>
+        /// <param name="arguments">The arguments to use to format the diagnostic message</param>
+        /// <returns>A <see cref="DiagnosticResult"/> with a <see cref="DiagnosticResult.Message"/> set with the <paramref name="descriptor"/>'s message format and the <paramref name="arguments"/>.</returns>
+        public static DiagnosticResult DiagnosticWithArguments(DiagnosticDescriptor descriptor, params object[] arguments)
+        {
+            // Generate the specific message here to ensure a stronger match with the correct diagnostic.
+            return Diagnostic(descriptor).WithMessage(string.Format(descriptor.MessageFormat.ToString(), arguments)).WithArguments(arguments);
+        }
+
         /// <inheritdoc cref="CodeFixVerifier{TAnalyzer, TCodeFix, TTest, TVerifier}.VerifyAnalyzerAsync(string, DiagnosticResult[])"/>
         public static async Task VerifyAnalyzerAsync(string source, params DiagnosticResult[] expected)
         {