How do you unit test ASP.NET Core MVC Controllers that return anonymous objects?

Question

I\'m having trouble unit testing ASP.NET Core MVC controllers that return anonymous objects. The unit testing is set up in a separate project and calls the controller method

Answer 1

Original idea from this answer with a more generic approach. Using a custom DynamicObject as a wrapper for inspecting the value via reflection there was no need to add the InternalsVisibleTo

public class DynamicObjectResultValue : DynamicObject, IEquatable<DynamicObjectResultValue> {
    private readonly object value;

    public DynamicObjectResultValue(object value) {
        this.value = value;
    }

    #region Operators
    public static bool operator ==(DynamicObjectResultValue a, DynamicObjectResultValue b) {
        // If both are null, or both are same instance, return true.
        if (System.Object.ReferenceEquals(a, b)) {
            return true;
        }
        // If one is null, but not both, return false.
        if (ReferenceEquals((object)a, null) || ReferenceEquals((object)b, null)) {
            return false;
        }
        // Return true if the fields match:
        return a.value == b.value;
    }

    public static bool operator !=(DynamicObjectResultValue a, DynamicObjectResultValue b) {
        return !(a == b);
    }
    #endregion

    public override IEnumerable<string> GetDynamicMemberNames() {
        return value.GetType().GetProperties().Select(p => p.Name);
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result) {
        //initialize value
        result = null;
        //Search possible matches and get its value
        var property = value.GetType().GetProperty(binder.Name);
        if (property != null) {
            // If the property is found, 
            // set the value parameter and return true. 
            var propertyValue = property.GetValue(value, null);
            result = propertyValue;
            return true;
        }
        // Otherwise, return false. 
        return false;
    }

    public override bool Equals(object obj) {
        if (obj is DynamicObjectResultValue)
            return Equals(obj as DynamicObjectResultValue);
        // If parameter is null return false.
        if (ReferenceEquals(obj, null)) return false;
        // Return true if the fields match:
        return this.value == obj;
    }

    public bool Equals(DynamicObjectResultValue other) {
        // If parameter is null return false.
        if (ReferenceEquals(other, null)) return false;
        // Return true if the fields match:
        return this.value == other.value;
    }

    public override int GetHashCode() {
        return ToString().GetHashCode();
    }

    public override string ToString() {
        return string.Format("{0}", value);
    }
}

Assuming the following controller

public class FooController : Controller {

    public IActionResult GetAnonymousObject() {

        var jsonResult = new {
            id = 1,
            name = "Foo",
            type = "Bar"
        };

        return Ok(jsonResult);
    }

    public IActionResult GetAnonymousCollection() {

        var jsonResult = Enumerable.Range(1, 20).Select(x => new {
            id = x,
            name = "Foo" + x,
            type = "Bar" + x
        }).ToList();

        return Ok(jsonResult);
    }
}

Tests could look like

[TestMethod]
public void TestDynamicResults() {
    //Arrange
    var controller = new FooController();

    //Act
    var result = controller.GetAnonymousObject() as OkObjectResult;

    //Assert
    dynamic obj = new DynamicObjectResultValue(result.Value);

    Assert.IsNotNull(obj);
    Assert.AreEqual(1, obj.id);
    Assert.AreEqual("Foo", obj.name);
    Assert.AreEqual(3, obj.name.Length);
    Assert.AreEqual("Bar", obj.type);
}

[TestMethod]
public void TestDynamicCollection() {
    //Arrange
    var controller = new FooController();

    //Act
    var result = controller.GetAnonymousCollection() as OkObjectResult;

    //Assert
    Assert.IsNotNull(result, "No ActionResult returned from action method.");
    dynamic jsonCollection = result.Value;
    foreach (dynamic value in jsonCollection) {
        dynamic json = new DynamicObjectResultValue(value);

        Assert.IsNotNull(json.id,
            "JSON record does not contain \"id\" required property.");
        Assert.IsNotNull(json.name,
            "JSON record does not contain \"name\" required property.");
        Assert.IsNotNull(json.type,
            "JSON record does not contain \"type\" required property.");
    }
}