Microsoft.R.Editor.Tree.EditorTree.EnsureTreeReady C# (CSharp) Method

        public void EnsureTreeReady() {
            if (TreeUpdateTask == null)
                return;

            if (_ownerThread != Thread.CurrentThread.ManagedThreadId)
                throw new ThreadStateException("Method should only be called on the main thread");

            // OK to run in sync if changes are pending since we need it updated now
            TreeUpdateTask.EnsureProcessingComplete();
        }

        public async Task ParameterTest_ComputeCurrentParameter01() {
            ITextBuffer textBuffer = new TextBufferMock("aov(", RContentTypeDefinition.ContentType);
            SignatureHelpSource source = new SignatureHelpSource(textBuffer, EditorShell);
            SignatureHelpSessionMock session = new SignatureHelpSessionMock(textBuffer, 0);
            TextViewMock textView = session.TextView as TextViewMock;
            List<ISignature> signatures = new List<ISignature>();

            using (var tree = new EditorTree(textBuffer, EditorShell)) {
                tree.Build();
                using (var document = new EditorDocumentMock(tree)) {

                    session.TrackingPoint = new TrackingPointMock(textBuffer, 4, PointTrackingMode.Positive, TrackingFidelityMode.Forward);
                    await PackageIndexUtility.GetFunctionInfoAsync(FunctionIndex, "aov");

                    tree.TakeThreadOwnerShip();
                    await source.AugmentSignatureHelpSessionAsync(session, signatures, tree.AstRoot);

                    signatures.Should().ContainSingle();

                    int index = GetCurrentParameterIndex(signatures[0] as SignatureHelp, signatures[0].CurrentParameter);
                    index.Should().Be(0);

                    textView.Caret = new TextCaretMock(textView, 5);
                    TextBufferUtility.ApplyTextChange(textBuffer, 4, 0, 1, "a");
                    index = GetCurrentParameterIndex(signatures[0] as SignatureHelp, signatures[0].CurrentParameter);
                    index.Should().Be(0);

                    textView.Caret = new TextCaretMock(textView, 6);
                    TextBufferUtility.ApplyTextChange(textBuffer, 5, 0, 1, ",");
                    tree.EnsureTreeReady();
                    index = GetCurrentParameterIndex(signatures[0] as SignatureHelp, signatures[0].CurrentParameter);
                    index.Should().Be(1);

                    textView.Caret = new TextCaretMock(textView, 7);
                    TextBufferUtility.ApplyTextChange(textBuffer, 6, 0, 1, ",");
                    tree.EnsureTreeReady();
                    index = GetCurrentParameterIndex(signatures[0] as SignatureHelp, signatures[0].CurrentParameter);
                    index.Should().Be(2);
                }
            }
        }