Added new message

src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.CodeFix.Testing/CodeFixTest`1.cs

@@ -692,7 +692,11 @@ namespace Microsoft.CodeAnalysis.Testing
 
             try
             {
-                if (expectedNumberOfIterations >= 0)
+                if (expectedNumberOfIterations == 0 && numberOfIterations <= 0)
+                {
+                    verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, "No code fixes were expected, but a fix was offered that made no changes to the code.");
+                }
+                else if (expectedNumberOfIterations >= 0)
                 {
                     verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, $"Expected '{expectedNumberOfIterations}' iterations but found '{expectedNumberOfIterations - numberOfIterations}' iterations.");
                 }
@@ -862,7 +866,11 @@ namespace Microsoft.CodeAnalysis.Testing
 
             try
             {
-                if (expectedNumberOfIterations >= 0)
+                if (expectedNumberOfIterations == 0 && numberOfIterations <= 0)
+                {
+                    verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, "No code fixes were expected, but a fix was offered that made no changes to the code.");
+                }
+                else if (expectedNumberOfIterations >= 0)
                 {
                     verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, $"Expected '{expectedNumberOfIterations}' iterations but found '{expectedNumberOfIterations - numberOfIterations}' iterations.");
                 }

src/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.CodeRefactoring.Testing/CodeRefactoringTest`1.cs

@@ -302,7 +302,11 @@ namespace Microsoft.CodeAnalysis.Testing
 
             try
             {
-                if (expectedNumberOfIterations >= 0)
+                if (expectedNumberOfIterations == 0 && numberOfIterations <= 0)
+                {
+                    verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, "No code fixes were expected, but a fix was offered that made no changes to the code.");
+                }
+                else if (expectedNumberOfIterations >= 0)
                 {
                     verifier.Equal(expectedNumberOfIterations, expectedNumberOfIterations - numberOfIterations, $"Expected '{expectedNumberOfIterations}' iterations but found '{expectedNumberOfIterations - numberOfIterations}' iterations.");
                 }

tests/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.CodeFix.Testing.UnitTests/MissingCodeFixMarkupTests.cs

@@ -78,7 +78,7 @@ namespace Microsoft.CodeAnalysis.Testing
             Assert.Equal(
                 """
                 Context: Iterative code fix application
-                Expected '0' iterations but found '1' iterations.
+                No code fixes were expected, but a fix was offered that made no changes to the code.
                 """.ReplaceLineEndings(),
                 exception.Message);
 
@@ -91,7 +91,7 @@ namespace Microsoft.CodeAnalysis.Testing
             Assert.Equal(
                 """
                 Context: Iterative code fix application
-                Expected '0' iterations but found '1' iterations.
+                No code fixes were expected, but a fix was offered that made no changes to the code.
                 """.ReplaceLineEndings(),
                 exception.Message);
         }

tests/Microsoft.CodeAnalysis.Testing/Microsoft.CodeAnalysis.CodeFix.Testing.UnitTests/MissingCodeFixTests.cs

@@ -82,7 +82,7 @@ namespace Microsoft.CodeAnalysis.Testing
             Assert.Equal(
                 """
                 Context: Iterative code fix application
-                Expected '0' iterations but found '1' iterations.
+                No code fixes were expected, but a fix was offered that made no changes to the code.
                 """.ReplaceLineEndings(),
                 exception.Message);
 
@@ -95,7 +95,7 @@ namespace Microsoft.CodeAnalysis.Testing
             Assert.Equal(
                 """
                 Context: Iterative code fix application
-                Expected '0' iterations but found '1' iterations.
+                No code fixes were expected, but a fix was offered that made no changes to the code.
                 """.ReplaceLineEndings(),
                 exception.Message);
         }