public void Test_RemoveDocument()
{
var expected = 12345;
var solution = CreateSolution(expected);
var analyzer = new SolutionSizeTracker.IncrementalAnalyzer();
// initialize
analyzer.NewSolutionSnapshotAsync(solution, CancellationToken.None).Wait();
AddSolution(analyzer, solution);
// remove document
var document = solution.Projects.First().Documents.First();
analyzer.RemoveDocument(document.Id);
var size = analyzer.GetSolutionSize(solution.Id);
var length = document.GetSyntaxTreeAsync().Result.Length;
Assert.Equal(expected - length, size);
}