add the tests i forgot in the last commit

src/Altinn.App.Api/Controllers/Conventions/AltinnApiJsonFormatter.cs

@@ -1,7 +1,6 @@
 using System.Text.Encodings.Web;
 using System.Text.Json;
 using Altinn.App.Api.Extensions;
-using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.Formatters;
 
 namespace Altinn.App.Api.Controllers.Conventions;

test/Altinn.App.Api.Tests/Controllers/Conventions/AltinnApiJsonFormatterTests.cs

@@ -0,0 +1,89 @@
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Json.Serialization.Metadata;
+using Altinn.App.Api.Controllers.Attributes;
+using Altinn.App.Api.Controllers.Conventions;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Formatters;
+
+namespace Altinn.App.Api.Tests.Controllers.Conventions;
+
+public class AltinnApiJsonFormatterTests
+{
+    [Fact]
+    public void CreateFormatter_WhenEncoderIsNull_SetsUnsafeRelaxedJsonEscaping()
+    {
+        // Arrange
+        string settingsName = "AltinnApi";
+        var serializerOptions = new JsonSerializerOptions
+        {
+            Encoder = null,
+            TypeInfoResolver = new DefaultJsonTypeInfoResolver()
+        };
+
+        // Act
+        var formatter = AltinnApiJsonFormatter.CreateFormatter(settingsName, serializerOptions);
+
+        // Assert
+        Assert.NotNull(formatter);
+        Assert.Equal(settingsName, formatter.SettingsName);
+        Assert.NotNull(formatter.SerializerOptions.Encoder);
+        Assert.Equal(JavaScriptEncoder.UnsafeRelaxedJsonEscaping, formatter.SerializerOptions.Encoder);
+    }
+
+    [Fact]
+    public void CreateFormatter_WhenEncoderIsNotNull_PreservesEncoder()
+    {
+        // Arrange
+        string settingsName = "AltinnApi";
+        var originalEncoder = JavaScriptEncoder.Default;
+        var serializerOptions = new JsonSerializerOptions
+        {
+            Encoder = originalEncoder,
+            TypeInfoResolver = new DefaultJsonTypeInfoResolver()
+        };
+
+        // Act
+        var formatter = AltinnApiJsonFormatter.CreateFormatter(settingsName, serializerOptions);
+
+        // Assert
+        Assert.NotNull(formatter);
+        Assert.Equal(settingsName, formatter.SettingsName);
+        Assert.Equal(originalEncoder, formatter.SerializerOptions.Encoder);
+    }
+
+    [Fact]
+    public void CanWriteResult_SettingsNameMatches_ReturnsTrue()
+    {
+        // Arrange
+        string settingsName = JsonSettingNames.AltinnApi;
+        var formatter = AltinnApiJsonFormatter.CreateFormatter(
+            settingsName,
+            new JsonSerializerOptions() { TypeInfoResolver = new DefaultJsonTypeInfoResolver() }
+        );
+
+        var httpContext = new DefaultHttpContext();
+
+        // Create an Endpoint with JsonSettingsNameAttribute
+        var endpoint = new Endpoint(
+            requestDelegate: null,
+            metadata: new EndpointMetadataCollection(new JsonSettingsNameAttribute(settingsName)),
+            displayName: null
+        );
+
+        httpContext.SetEndpoint(endpoint);
+
+        var context = new OutputFormatterWriteContext(
+            httpContext,
+            (stream, encoding) => new StreamWriter(stream, encoding),
+            typeof(object),
+            new object()
+        );
+
+        // Act
+        bool canWrite = formatter.CanWriteResult(context);
+
+        // Assert
+        Assert.True(canWrite);
+    }
+}

test/Altinn.App.Api.Tests/Controllers/Conventions/AltinnControllerConventionTests.cs

@@ -0,0 +1,31 @@
+using System.Reflection;
+using Altinn.App.Api.Controllers.Attributes;
+using Altinn.App.Api.Controllers.Conventions;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+
+namespace Altinn.App.Api.Tests.Controllers.Conventions;
+
+public class AltinnControllerConventionsTests
+{
+    [Fact]
+    public void Apply_AddsJsonSettingsNameAttributeToControllerModel()
+    {
+        // Arrange
+        var convention = new AltinnControllerConventions();
+        var controllerType = typeof(TestController).GetTypeInfo();
+        var controllerModel = new ControllerModel(controllerType, []);
+
+        // Act
+        convention.Apply(controllerModel);
+
+        // Assert
+        var attribute = controllerModel.Filters.OfType<JsonSettingsNameAttribute>().FirstOrDefault();
+
+        Assert.NotNull(attribute);
+        Assert.Equal(JsonSettingNames.AltinnApi, attribute.Name);
+    }
+
+    // Dummy controller
+    private class TestController : ControllerBase { }
+}