Add wholesome test to check JSON names (#1609)

src/StripeTests/Wholesome/JsonNamesAreSnakeCase.cs

@@ -0,0 +1,57 @@
+#if NETCOREAPP
+namespace StripeTests
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Reflection;
+    using System.Text.RegularExpressions;
+    using Newtonsoft.Json;
+    using Stripe;
+    using Xunit;
+
+    /// <summary>
+    /// This wholesome test ensures that no entity or options class reuses the same name in
+    /// different `JsonProperty` attributes.
+    /// </summary>
+    public class JsonNamesAreSnakeCase : WholesomeTest
+    {
+        private const string AssertionMessage =
+            "Found at least one invalid JsonProperty name.";
+
+        [Fact]
+        public void Check()
+        {
+            List<string> results = new List<string>();
+
+            // Get all classes that derive from StripeEntity or implement INestedOptions
+            var stripeClasses = GetSubclassesOf(typeof(StripeEntity));
+            stripeClasses.AddRange(GetClassesWithInterface(typeof(INestedOptions)));
+
+            foreach (Type stripeClass in stripeClasses)
+            {
+                foreach (PropertyInfo property in stripeClass.GetProperties())
+                {
+                    var propType = property.PropertyType;
+
+                    // Skip properties that don't have a `JsonProperty` attribute
+                    var attribute = property.GetCustomAttribute<JsonPropertyAttribute>();
+                    if (attribute == null)
+                    {
+                        continue;
+                    }
+
+                    var match = Regex.Match(attribute.PropertyName, "^[a-z0-9][a-z0-9_]*$");
+
+                    if (!match.Success)
+                    {
+                        results.Add($"{stripeClass.Name}.{property.Name}");
+                    }
+                }
+            }
+
+            AssertEmpty(results, AssertionMessage);
+        }
+    }
+}
+#endif