Exact Error Codes for Error Collections

src/JsonApiDotNetCore/Internal/JsonApiException.cs

@@ -41,7 +41,7 @@ public JsonApiException(int statusCode, string message, Exception innerException
 
         public int GetStatusCode()
         {
-            if (_errors.Errors.Count == 1)
+            if (_errors.Errors.Select(a => a.StatusCode).Distinct().Count() == 1)
                 return _errors.Errors[0].StatusCode;
 
             if (_errors.Errors.FirstOrDefault(e => e.StatusCode >= 500) != null)

test/UnitTests/Internal/JsonApiException_Test.cs

@@ -0,0 +1,31 @@
+using JsonApiDotNetCore.Internal;
+using Xunit;
+
+namespace UnitTests.Internal
+{
+    public class JsonApiException_Test
+    {
+        [Fact]
+        public void Can_GetStatusCode()
+        {
+            var errors = new ErrorCollection();
+            var exception = new JsonApiException(errors);
+
+            // Add First 422 error
+            errors.Add(new Error(422, "Something wrong"));
+            Assert.Equal(422, exception.GetStatusCode());
+
+            // Add a second 422 error
+            errors.Add(new Error(422, "Something else wrong"));
+            Assert.Equal(422, exception.GetStatusCode());
+
+            // Add 4xx error not 422
+            errors.Add(new Error(401, "Unauthorized"));
+            Assert.Equal(400, exception.GetStatusCode());
+
+            // Add 5xx error not 4xx
+            errors.Add(new Error(502, "Not good"));
+            Assert.Equal(500, exception.GetStatusCode());
+        }
+    }
+}