SpecFlow XTC screenshot workaround

XamarinTestCloudHooks.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
using TechTalk.SpecFlow;
using TechTalk.SpecFlow.Bindings;
using TechTalk.SpecFlow.Bindings.Reflection;
using TechTalk.SpecFlow.Tracing;
using Xamarin.UITest;
using Xamarin.UITest.Events;

namespace SpecFlowHooks
{
    [Binding]
    public class XamarinTestCloudHooks
    {
        static IApp _app;

        [AfterAppStarted]
        public static void AfterAppStarted(IApp app)
        {
            _app = app;
        }
        
        [BeforeScenario]
        public void BeforeScenario()
        {
            var testRunner = TestRunnerManager.GetTestRunner();
            var executionEngineField = testRunner.GetType().GetField("executionEngine", BindingFlags.Instance | BindingFlags.NonPublic);
            var executionEngine = executionEngineField.GetValue(testRunner);
            var testTracerField = executionEngine.GetType().GetField("testTracer", BindingFlags.Instance | BindingFlags.NonPublic);
            
            var testTracerValue = testTracerField.GetValue(executionEngine);

            if (testTracerValue is TestTracerDecorator)
            {
                // Already decorated.
                return;
            }

            testTracerField.SetValue(executionEngine, new TestTracerDecorator(testTracerValue as ITestTracer));
        }

        class TestTracerDecorator : ITestTracer
        {
            readonly ITestTracer _testTracer;
            StepInstance _currentStepInstance;

            public TestTracerDecorator(ITestTracer testTracer)
            {
                _testTracer = testTracer;
            }

            public void TraceStep(StepInstance stepInstance, bool showAdditionalArguments)
            {
                _currentStepInstance = stepInstance;
                _testTracer.TraceStep(stepInstance, showAdditionalArguments);
            }

            public void TraceWarning(string text)
            {
                _testTracer.TraceWarning(text);
            }

            public void TraceStepDone(BindingMatch match, object[] arguments, TimeSpan duration)
            {
                if (_currentStepInstance != null && _app != null)
                {
                    _app.Screenshot(string.Format("{0} {1}", _currentStepInstance.Keyword, _currentStepInstance.Text));
                }

                _testTracer.TraceStepDone(match, arguments, duration);
            }

            public void TraceStepSkipped()
            {
                _testTracer.TraceStepSkipped();
            }

            public void TraceStepPending(BindingMatch match, object[] arguments)
            {
                _testTracer.TraceStepPending(match, arguments);
            }

            public void TraceBindingError(BindingException ex)
            {
                _testTracer.TraceBindingError(ex);
            }

            public void TraceError(Exception ex)
            {
                _testTracer.TraceError(ex);
            }

            public void TraceNoMatchingStepDefinition(StepInstance stepInstance, ProgrammingLanguage targetLanguage,
                CultureInfo bindingCulture, List<BindingMatch> matchesWithoutScopeCheck)
            {
                _testTracer.TraceNoMatchingStepDefinition(stepInstance, targetLanguage, bindingCulture, matchesWithoutScopeCheck);
            }

            public void TraceDuration(TimeSpan elapsed, IBindingMethod method, object[] arguments)
            {
                _testTracer.TraceDuration(elapsed, method, arguments);
            }

            public void TraceDuration(TimeSpan elapsed, string text)
            {
                _testTracer.TraceDuration(elapsed, text);
            }
        }
    }
}