added better example in unit test

test/ValidationTests.cs

@@ -2,6 +2,7 @@
 using HotChocolate.Execution;
 using Microsoft.Extensions.DependencyInjection;
 using Snapshooter.Xunit;
+using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Threading.Tasks;
 using Xunit;
@@ -10,66 +11,82 @@ namespace Graph.ArgumentValidator
 {
     public class ValidationTests
     {
-        [Fact]
-        public async Task Ensure_Validation_Works_On_Arguments()
+        /// <summary>
+        /// Gives the JSON result of execution
+        /// </summary>
+        /// <param name="request">GraphQL query to be executed</param>
+        /// <returns>JSON result of GraphQL Query</returns>
+        static async Task<string> ExecuteRequest(string request)
         {
-            var result =
-                await new ServiceCollection()
-                    .AddScoped(_ => new Service())
+            var resonse = await new ServiceCollection()
+                    .AddScoped(_ => new DataValidatorService())
                     .AddGraphQL()
                     .AddQueryType<Query>()
                     .AddArgumentValidator()
-                    .ExecuteRequestAsync("{ argIsEmail(email: \"abc\") }");
+                    .ExecuteRequestAsync(request);
+            return resonse.ToJson();
+        }
+
+        [Fact]
+        public async Task Ensure_Validation_Works_On_Arguments()
+        {
+            var result = await ExecuteRequest("{ argIsEmail(email: \"abc\") }");
 
-            result.ToJson().MatchSnapshot();
+            result.MatchSnapshot();
         }
 
         [Fact]
         public async Task Ensure_Validation_Works_On_Arguments_ValidEmail()
         {
-            var result =
-                await new ServiceCollection()
-                    .AddScoped(_ => new Service())
-                    .AddGraphQL()
-                    .AddQueryType<Query>()
-                    .AddArgumentValidator()
-                    .ExecuteRequestAsync("{ argIsEmail(email: \"[email protected]\") }");
+            var result = await ExecuteRequest("{ argIsEmail(email: \"[email protected]\") }");
 
-            result.ToJson().MatchSnapshot();
+            result.MatchSnapshot();
         }
 
         [Fact]
         public async Task Ensure_Validation_Works_On_InputObjects()
         {
-            var result =
-                await new ServiceCollection()
-                    .AddScoped(_ => new Service())
-                    .AddGraphQL()
-                    .AddQueryType<Query>()
-                    .AddArgumentValidator()
-                    .ExecuteRequestAsync("{ argIsInput(input: { email: \"abc\" }) }");
+            var result = await ExecuteRequest("{ argIsInput(input: { email: \"abc\" }) }");
 
-            result.ToJson().MatchSnapshot();
+            result.MatchSnapshot();
         }
 
         [Fact]
         public async Task Ensure_Validation_Works_On_InputObjects_ValidEmail()
         {
-            var result =
-                await new ServiceCollection()
-                    .AddScoped(_ => new Service())
-                    .AddGraphQL()
-                    .AddQueryType<Query>()
-                    .AddArgumentValidator()
-                    .ExecuteRequestAsync("{ argIsInput(input: { email: \"[email protected]\" }) }");
+            var result = await ExecuteRequest("{ argIsInput(input: { email: \"[email protected]\" }) }");
 
-            result.ToJson().MatchSnapshot();
+            result.MatchSnapshot();
+        }
+
+
+        [Fact]
+        public async Task Ensure_Validation_Works_On_DuplicateEmail()
+        {
+            var result = await ExecuteRequest("{ checkDuplicateEmail( email: \"[email protected]\" ) }");
+
+            result.MatchSnapshot();
+        }
+
+        [Fact]
+        public async Task Ensure_Validation_Works_On_NonDuplicateEmail()
+        {
+            var result = await ExecuteRequest("{ checkDuplicateEmail( email: \"[email protected]\" ) }");
+
+            result.MatchSnapshot();
         }
     }
 
     public class Query
     {
-        public string ArgIsEmail([EmailAddress][ResolveService] string email) => email;
+        public string ArgIsEmail([EmailAddress] string email) => email;
+
+        /// <summary>
+        /// Gives validation failed result if email already exist. Other wise *You are good to go...*
+        /// </summary>
+        /// <param name="email"></param>
+        /// <returns></returns>
+        public string CheckDuplicateEmail([EmailAddress][DuplicateEmailValidtor] string email) => "You are good to go, this email not registred yet.";
 
         public string ArgIsInput(MyInput input) => input.Email;
     }
@@ -78,21 +95,30 @@ public class Query
     public class MyInput
     {
         [EmailAddress]
-        [ResolveService]
         public string Email { get; set; }
     }
 
-    public class Service
+    public class DataValidatorService
     {
-        public bool CouldBeResolved => true;
+        public bool IsEmailExist(string newEmail)
+        {
+            var existingEmails = new List<string>
+            {
+                "[email protected]",
+                "[email protected]"
+            };
+
+            return !existingEmails.Contains(newEmail);
+        }
     }
 
-    public class ResolveServiceAttribute : ValidationAttribute
+    public class DuplicateEmailValidtorAttribute : ValidationAttribute
     {
-        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
+        protected override ValidationResult IsValid(object valueObj, ValidationContext validationContext)
         {
-            var service = (Service)validationContext.GetService(typeof(Service));
-            return service is { CouldBeResolved: true } ? ValidationResult.Success : new ValidationResult("error");
+            var value = valueObj as string;
+            var service = (DataValidatorService)validationContext.GetService(typeof(DataValidatorService));
+            return service.IsEmailExist(value) ? ValidationResult.Success : new ValidationResult("Email already exist");
         }
     }
 }

test/__snapshots__/ValidationTests.Ensure_Validation_Works_On_DuplicateEmail.snap

@@ -0,0 +1,16 @@
+{
+  "errors": [
+    {
+      "message": "Email already exist",
+      "path": [
+        "email"
+      ],
+      "extensions": {
+        "field": "email"
+      }
+    }
+  ],
+  "data": {
+    "checkDuplicateEmail": null
+  }
+}

test/__snapshots__/ValidationTests.Ensure_Validation_Works_On_NonDuplicateEmail.snap

@@ -0,0 +1,5 @@
+{
+  "data": {
+    "checkDuplicateEmail": "You are good to go, this email not registred yet."
+  }
+}