Fix test setup for TestEngine

The tests failed prematurely because the actual work was done on a background thread that had not reached to end when the assert was executed.

Author: MDoerner

Rubberduck.UnitTesting/UnitTesting/TestEngine.cs

@@ -19,7 +19,7 @@ namespace Rubberduck.UnitTesting
     // FIXME litter logging around here
     internal class TestEngine : ITestEngine
     {
-        private static readonly ParserState[] AllowedRunStates = 
+        protected static readonly ParserState[] AllowedRunStates = 
         {
             ParserState.Ready
         };
@@ -171,7 +171,7 @@ public void RequestCancellation()
             CancellationRequested = true;
         }
 
-        private void RunInternal(IEnumerable<TestMethod> tests)
+        protected virtual void RunInternal(IEnumerable<TestMethod> tests)
         {
             if (!CanRun)
             {
@@ -199,15 +199,15 @@ private void EnsureRubberduckIsReferencedForEarlyBoundTests()
             }
         }
 
-        private void RunWhileSuspended(IEnumerable<TestMethod> tests)
+        protected void RunWhileSuspended(IEnumerable<TestMethod> tests)
         {
             //Running the tests has to be done on the UI thread, so we push the task to it from within suspension of the parser.
             //We have to wait for the completion to make sure that the suspension only ends after tests have been completed.
-            var testTask = _uiDispatcher.StartTask(() => RunWhileSuspendedOnUIThread(tests));
+            var testTask = _uiDispatcher.StartTask(() => RunWhileSuspendedOnUiThread(tests));
             testTask.Wait();
         }
 
-        private void RunWhileSuspendedOnUIThread(IEnumerable<TestMethod> tests)
+        private void RunWhileSuspendedOnUiThread(IEnumerable<TestMethod> tests)
         {
             var testMethods = tests as IList<TestMethod> ?? tests.ToList();
             if (!testMethods.Any())

RubberduckTests/UnitTesting/MockedTestEngine.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Threading.Tasks;
 using Moq;
 using NUnit.Framework;
 using Rubberduck.Parsing.UIContext;
@@ -47,8 +48,17 @@ internal class MockedTestEngine : IDisposable
 
         private MockedTestEngine()
         {
-            Dispatcher.Setup(d => d.InvokeAsync(It.IsAny<Action>())).Callback((Action action) => action.Invoke()).Verifiable();
-            
+            Dispatcher.Setup(d => d.InvokeAsync(It.IsAny<Action>()))
+                .Callback((Action action) => action.Invoke())
+                .Verifiable();
+            Dispatcher.Setup(d => d.StartTask(It.IsAny<Action>(), It.IsAny<TaskCreationOptions>()))
+                .Returns((Action action, TaskCreationOptions options) =>
+                    {
+                        action.Invoke();
+                        return Task.CompletedTask;
+                    })
+                .Verifiable();
+
             TypeLib.Setup(tlm => tlm.Dispose()).Verifiable();
             WrapperProvider.Setup(p => p.TypeLibWrapperFromProject(It.IsAny<string>())).Returns(TypeLib.Object).Verifiable();
 
@@ -64,7 +74,7 @@ public MockedTestEngine(string testModuleCode) : this()
 
             Vbe = builder.Build();
             ParserState = MockParser.Create(Vbe.Object).State;
-            TestEngine = new TestEngine(ParserState, _fakesFactory.Object, VbeInteraction.Object, WrapperProvider.Object, Dispatcher.Object, Vbe.Object);
+            TestEngine = new SynchronouslySuspendingTestEngine(ParserState, _fakesFactory.Object, VbeInteraction.Object, WrapperProvider.Object, Dispatcher.Object, Vbe.Object);
         }
 
         public MockedTestEngine(IReadOnlyList<string> moduleNames, IReadOnlyList<int> methodCounts) : this()
@@ -87,7 +97,7 @@ public MockedTestEngine(IReadOnlyList<string> moduleNames, IReadOnlyList<int> me
             project.AddProjectToVbeBuilder();
             Vbe = builder.Build();
             ParserState = MockParser.Create(Vbe.Object).State;
-            TestEngine = new TestEngine(ParserState, _fakesFactory.Object, VbeInteraction.Object, WrapperProvider.Object, Dispatcher.Object, Vbe.Object);
+            TestEngine = new SynchronouslySuspendingTestEngine(ParserState, _fakesFactory.Object, VbeInteraction.Object, WrapperProvider.Object, Dispatcher.Object, Vbe.Object);
         }
 
         public MockedTestEngine(int testMethodCount) 
@@ -246,5 +256,32 @@ Public Sub TestCleanup()
     'this method runs after every test in the module.
 End Sub
 ";
+
+        private class SynchronouslySuspendingTestEngine : TestEngine
+        {
+            private readonly RubberduckParserState _state;
+
+            public SynchronouslySuspendingTestEngine(
+                RubberduckParserState state,
+                IFakesFactory fakesFactory,
+                IVBEInteraction declarationRunner,
+                ITypeLibWrapperProvider wrapperProvider,
+                IUiDispatcher uiDispatcher,
+                IVBE vbe)
+                : base(state, fakesFactory, declarationRunner, wrapperProvider, uiDispatcher, vbe)
+            {
+                _state = state;
+            }
+
+            protected override void RunInternal(IEnumerable<TestMethod> tests)
+            {
+                if (!CanRun)
+                {
+                    return;
+                }
+                //We have to do this on the same thread here to guarantee that the actions runs before the assert in the unit tests is called.
+                _state.OnSuspendParser(this, AllowedRunStates, () => RunWhileSuspended(tests));
+            }
+        }
     }
 }