This is an article about using Roslyn Workspaces to run quick one-off analysis on your .NET projects without going into complexities of analyzers and code-fixes. It builds upon part 1, where we created a query that analyzed logical expressions inside our code-base. This time we will use Workspaces to replace invocations of an obsolete method with a newer version.
Our synthetic code-base emulates a reporting system for a big corporation. The system pulls together information form accounting, HR, sales and supply systems and prepares analytical reports for our users. It's a big system that has been around for over a decade, so there is quite a bit of legacy code in it. Today we finally decided to get rid of the obsolete overload of our most called method ScheduleReport. We want to replace:
var scheduleId = reportSchedulingSystem.ScheduleReport(reportName, false, id, null, null, null);
var scheduleId = reportSchedulingSystem.ScheduleReport( reportName, new UserIdsAcrossSystems(userIdInAccountingSystem: id), false).id;
in a fully automated manner.
From the point of view of developer using it (we will call them 'user-dev'), Refactorings in Roslyn are additional commands that pop-up in Visual Studio when they click certain pieces of code. From our point of view, Refactorings are classes inheriting from CodeRefactoringProvider, which get a chance to examine current syntax graph every time user-dev clicks something in it and determine, if they should offer any transformations of that graph based on its state and what was clicked.
We will be building a Refactoring which allows our user-dev to regenerate a given classes public constructor by adding to it any missing assignment of members that match a certain pattern and are not yet assigned during construction. Specifically, this is the refactoring we use at work to regenerate dependency injected constructors.