Added STJ tests for deserializing null values (#3224)

Author: prathmesh-stripe

src/StripeTests/Infrastructure/SerializationTest.cs

@@ -44,6 +44,14 @@ public void Serialize()
                 JsonConvert.DeserializeObject<Event>(serialized),
                 Formatting.Indented);
             Assert.Equal(serialized, reserialized);
+
+            json = GetResourceAsString("api_fixtures.customer_with_expansions.json");
+            var customer = JsonConvert.DeserializeObject<Customer>(json);
+            serialized = JsonConvert.SerializeObject(customer, Formatting.Indented);
+            reserialized = JsonConvert.SerializeObject(
+                JsonConvert.DeserializeObject<Customer>(serialized),
+                Formatting.Indented);
+            Assert.Equal(serialized, reserialized);
         }
     }
 }

src/StripeTests/Infrastructure/StjDeserializationTest.cs

@@ -0,0 +1,51 @@
+#if NET6_0_OR_GREATER
+namespace StripeTests
+{
+    using System;
+    using System.Text.Json;
+    using System.Xml;
+    using Stripe;
+    using StripeTests.Infrastructure.TestData;
+    using Xunit;
+
+    public class StjDeserializationTest : BaseStripeTest
+    {
+        [Fact]
+        public void RoundtripDatetime()
+        {
+            var date = DateTime.UtcNow;
+            var roundedDate = date.AddTicks(-1 * (date.Ticks % TimeSpan.TicksPerSecond));
+            var obj = new TestObjectDateTime
+            {
+                Date = roundedDate,
+            };
+
+            var reloaded = JsonSerializer.Deserialize<TestObjectDateTime>(JsonSerializer.Serialize(obj));
+            Assert.Equal(reloaded.Date, obj.Date);
+        }
+
+        [Fact]
+        public void HandleNull()
+        {
+            var obj = new TestObjectDateTime
+            {
+                Date = null,
+            };
+
+            var reloaded = JsonSerializer.Deserialize<TestObjectDateTime>(JsonSerializer.Serialize(obj));
+            Assert.Null(reloaded.Date);
+        }
+
+        [Fact(Skip="System.Text.JSON Deserialization does not work correctly currently for handling non-nullable null values")]
+        public void Serialize()
+        {
+            var json = GetResourceAsString("api_fixtures.customer_with_expansions.json");
+            var customer = JsonSerializer.Deserialize<Customer>(json);
+            var serialized = JsonSerializer.Serialize(customer);
+            var reserialized = JsonSerializer.Serialize(
+                JsonSerializer.Deserialize<Customer>(serialized));
+            Assert.Equal(serialized, reserialized);
+        }
+    }
+}
+#endif