Using Reflection Causing MissingMethodException in Xamarin UITest - unit-testing

Question

I have a class in my Xamarin PCL which makes a call to System.Reflection.GetRuntimeProperties. For an example, let's say my PCL class has this method:
public string ExampleMethod(string arg) {
if(arg == null) return null;
IEnumerable<PropertyInfo> infos = this.GetType().GetRuntimeProperties();
return infos[0].Name;
}
I then have a Xamarin.UITest project which references the PCL project and tests this class. I have two test cases in my TestFixture so far, which for our example would be the following:
[Test]
public void TestExampleMethod_ArgNull_Null(){
Assert.That (exampleInstance.ExampleMethod(null), Is.Null);
}
[Test]
public void TestExampleMethod_ArgNotNull_NotNull(){
Assert.That (exampleInstance.ExampleMethod("testValue"), Is.NotNull);
}
When I run the Xamarin.UITest project, it compiles, runs the tests, and completes fine on both Android and iOS platforms. The TestExampleMethod_ArgNull_Null test passes since it returns early. However, the TestExampleMethod_ArgNotNull_NotNull test fails with:
System.MissingMethodException : Method 'RuntimeReflectionExtensions.GetRuntimeProperties' not found.
So it appears that even though everything is compiling just fine, and I am able to run other test cases fine, the Xamarin.UITest project is not able to use anything in System.Reflection. Does anyone know how I go about debugging this?

Answer 1

On my end, using the following failed to build:
IEnumerable<PropertyInfo> infos = this.GetType().GetRuntimeProperties();
return infos[0].Name;
due to not being able to do bracket indexes on and IEnumerable. I changed to this:
List<PropertyInfo> infos = this.GetType().GetRuntimeProperties().ToList();
return infos[0].Name;
And the project built and the tests ran successfully.
The class with the method using Reflection was in a PCL which was referenced from a UI Test project.
So basically I am not able to reproduce the error you got.

Answer 2

I posted this to Xamarin Support as well (thanks #jgoldberger) and we were able to figure out that it was due to a project setup issue. This is a project which uses Couchbase Lite which requires a specific version of Json.Net (6.0.4 as of this post). I must have accidentally updated the packages on some of the projects since the same version of Json.Net was not being used across all the projects (PCL, Android, iOS, and UITest). I ended up re-creating the project from scratch and that took care of it.