In the previous post in the Roslyn series we have explored how we could create code analyzers and how to test them, to reduce the cognitive load on our development team! However, what if we take an extra mile and create a Code Fix Provider to provide some suggestions for the developers! Shall we?
In the previous post we have seen how it is possible to create a diagnostic analyzer using Roslyn APIs. Being a TDD advocate it would be disappointing not to talk about how we could test our code analyzer! So let's take a look into it.
We are all familiar with diagnostics that are provided from the compiler when we develop an application, they could be in form of warnings, errors or code suggestions. A diagnostic or code analyzer, inspects our open files for various metrics, like style, maintainability, design, etc. However, sometimes we need to write a tailor-made analysis for our specific situation, tool, or project.
A syntax tree has knowledge about the textual content of what it represents and that content relates to C#. There are scenarios that we need to change the code, such as code fixes, refactorings, or advanced source generation, and it could be done through changing the syntax tree; since this is a bidirectional relationship. There are two approaches, Replacement Methods and SyntaxRewriter classes
Sometimes when we want to generate code whether it is source generators or code fixes for a code analyzer, it is required to know how a syntax tree could be created using the Roslyn Compiler API. There are two ways, that we will discuss them in this post.
Compilers used to be a black box, they were accepting a bunch of source files as input and were producing an artifact as an output! There were no means of interaction with any of the phases inside the compiler pipeline. However, with Roslyn, The .NET Compiler Platform SDK, it is not the case anymore!