Add better tests for emtpy string/model to null conversion

Author: JonasSchneegans

Diff for: MaLoIdentModels/MaLoIdentModelsTests/v1Tests/SinglePropertyDeserializationTests.cs

@@ -0,0 +1,123 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using FluentAssertions;
+using MaLoIdentModels.JsonSettings;
+
+namespace MaLoIdentModelsTests.v1Tests;
+
+public class SinglePropertyDeserializationTests
+{
+    private const string JsonWithEmptyString = "{\"OptionalStringField\":\"\"}";
+
+    private const string JsonWithEmptyLists = "{\"EmptylistField\":[]}";
+
+    private const string JsonWithEmptyObjectsList =
+        "{\"ListWithEmptyObjectsField\":[{\"Field\":\"\"}]}";
+
+    private const string JsonWithEmptyNestedObjectsList =
+        "{\"ListWithEmptyObjectsField\":[{\"Field\":{\"Field\":\"\"}}]}";
+
+    internal class SomethingWithAOptionalStringField
+    {
+        [JsonConverter(typeof(EmptyStringConverter))]
+        [JsonPropertyName("OptionalStringField")]
+        public string? OptionalStringField { get; set; }
+    }
+
+    internal class SomethingWithAnEmptyListField
+    {
+        [JsonConverter(typeof(EmptyListToNullConverter<string>))]
+        [JsonPropertyName("EmptyListField")]
+        public List<string>? EmptyListField { get; set; }
+    }
+
+    internal class ObjectForList
+    {
+        [JsonPropertyName("Field")]
+        public string? Field { get; set; }
+    }
+
+    internal class SomethingWithAnEmptyObjectListField
+    {
+        [JsonConverter(typeof(EmptyListToNullConverter<ObjectForList>))]
+        [JsonPropertyName("ListWithEmptyObjectsField")]
+        public List<ObjectForList>? ListWithEmptyObjectsField { get; set; }
+    }
+
+    internal class NestedObject
+    {
+        [JsonPropertyName("Field")]
+        public ObjectForList? Field { get; set; }
+    }
+
+    internal class SomethingWithAnNestedEmptyObjectListField
+    {
+        [JsonConverter(typeof(EmptyListToNullConverter<ObjectForList>))]
+        [JsonPropertyName("ListWithEmptyNestedObjectsField")]
+        public List<ObjectForList>? ListWithEmptyNestedObjectsField { get; set; }
+    }
+
+    [Fact]
+    public void Test_Models_With_Empty_Strings()
+    {
+        var deserializing = () =>
+            JsonSerializer.Deserialize<SomethingWithAOptionalStringField>(JsonWithEmptyString);
+        var deserializedModel = deserializing();
+        deserializedModel.Should().NotBeNull();
+        deserializedModel
+            .OptionalStringField.Should()
+            .BeNull(because: "empty strings should be intpreted as null");
+        var reSererialized = JsonSerializer.Serialize(deserializedModel);
+        reSererialized.Should().BeEquivalentTo("{\"OptionalStringField\":null}");
+    }
+
+    [Fact]
+    public void Test_Models_With_Empty_Lists()
+    {
+        var deserializing = () =>
+            JsonSerializer.Deserialize<SomethingWithAnEmptyListField>(JsonWithEmptyLists);
+        var deserializedModel = deserializing();
+        deserializedModel.Should().NotBeNull();
+        deserializedModel
+            .EmptyListField.Should()
+            .BeNull(because: "empty lists should be intpreted as null");
+        var reSererialized = JsonSerializer.Serialize(deserializedModel);
+        reSererialized.Should().BeEquivalentTo("{\"EmptylistField\":null}");
+    }
+
+    [Fact]
+    public void Test_List_With_Empty_Models()
+    {
+        var deserializing = () =>
+            JsonSerializer.Deserialize<SomethingWithAnEmptyObjectListField>(
+                JsonWithEmptyObjectsList
+            );
+        var deserializedModel = deserializing();
+        deserializedModel.Should().NotBeNull();
+        deserializedModel
+            .ListWithEmptyObjectsField.Should()
+            .BeNull(
+                because: "lists with objects where all fields are an empty string should be null"
+            );
+        var reSererialized = JsonSerializer.Serialize(deserializedModel);
+        reSererialized.Should().BeEquivalentTo("{\"ListWithEmptyObjectsField\":null}");
+    }
+
+    [Fact]
+    public void Test_List_With_Empty_Nested_Models()
+    {
+        var deserializing = () =>
+            JsonSerializer.Deserialize<SomethingWithAnNestedEmptyObjectListField>(
+                JsonWithEmptyNestedObjectsList
+            );
+        var deserializedModel = deserializing();
+        deserializedModel.Should().NotBeNull();
+        deserializedModel
+            .ListWithEmptyNestedObjectsField.Should()
+            .BeNull(
+                because: "lists with objects where all fields are an empty string should be null"
+            );
+        var reSererialized = JsonSerializer.Serialize(deserializedModel);
+        reSererialized.Should().BeEquivalentTo("{\"ListWithEmptyNestedObjectsField\":null}");
+    }
+}