Failure ToString: embrace the FailureCode value with quotes

Author: andreise

src/core-taggeds-failure/Failure.Tests/Test.Failure/Test.ToString.cs

@@ -94,7 +94,7 @@ private static string InnerBuildExpectedFailureToString<TFailureCode>(
         where TFailureCode : struct
         =>
         string.Format(
-            "Failure<{0}>:{{ \"FailureCode\": {1}, \"FailureMessage\": \"{2}\", \"SourceException\": null }}",
+            "Failure<{0}>:{{ \"FailureCode\": \"{1}\", \"FailureMessage\": \"{2}\", \"SourceException\": null }}",
             typeof(TFailureCode).Name,
             failureCodeString,
             failureMessage);
@@ -106,7 +106,7 @@ private static string InnerBuildExpectedFailureToString<TFailureCode>(
         where TFailureCode : struct
         =>
         string.Format(
-            "Failure<{0}>:{{ \"FailureCode\": {1}, \"FailureMessage\": \"{2}\", \"SourceException\": \"{3}\" }}",
+            "Failure<{0}>:{{ \"FailureCode\": \"{1}\", \"FailureMessage\": \"{2}\", \"SourceException\": \"{3}\" }}",
             typeof(TFailureCode).Name,
             failureCodeString,
             failureMessage,

src/core-taggeds-failure/Failure/Failure.T/T.ToString.cs

@@ -8,7 +8,7 @@ public override string ToString()
         =>
         string.Format(
             CultureInfo.InvariantCulture,
-            "Failure<{0}>:{{ \"FailureCode\": {1}, \"FailureMessage\": \"{2}\", \"SourceException\": {3}{4}{5} }}",
+            "Failure<{0}>:{{ \"FailureCode\": \"{1}\", \"FailureMessage\": \"{2}\", \"SourceException\": {3}{4}{5} }}",
             typeof(TFailureCode).Name,
             FailureCode,
             FailureMessage,