You've made a lot of progress. You’ll do it in two ways: you’ll use a scripting engine first, and then you’ll see how it’s done by compiling and executing the code. You use the Syntax API for any analysis of the structure of C# code. The code for almost every test for your analyzer follows one of these two patterns. Contents Add const to both i and j, and you get a new warning on k because it can now be const. This code snippet verifies that condition: To be thorough, you need to add another test to make sure that you can create a constant declaration for a string. Create diagnostics. To fix this bug, the code fix must replace the var keyword with the inferred type's name: These changes update the data row declarations for both tests. Again, note that you’re using full type names for the return type (if it’s not void) and the parameter types. Figure 1 Interaction with the ScriptEngine. Now the Person object doesn’t care how IAddressService is implemented and you can use mocks for Person-based unit tests. If there are no differences in the parameter types, you’ve found a match, and that’s what you return (Lines 32-36). There are numerous possible declaration statements where this implementation makes mistakes. Introduction # One of the major parts of the Roslyn compiler is the Syntax API. It's often the case that your analyzer will be called for code that doesn't compile. Let’s fill these holes in the code: Other than generating the methods, everything else is fairly boilerplate. Then, you use the results of this data flow analysis to ensure that the local variable isn't written with a new value anywhere else. As you saw in the last example, you used SyntaxTree.ParseCompilationUnit() to create a tree structure that represents the code you pass into the method. Listing 4 Compiling code at runtime with Roslyn. Visual Studio calls registered analyzers as the user edits code. As you build your analyzer and code fix, you'll write tests for different code structures to verify your work. Introduction. C# and Visual Basic Language Feature Suggestions. Make the following changes to AnalyzeNode: In your AnalyzeNode method, replace the original semantic analysis: The first foreach loop examines each variable declaration using syntactic analysis. Responsiveness is a key requirement. A better approach would be to break the direct dependency on AddressService as Figure 4 shows: Figure 4 Using an interface in code. All code fix providers derive from CodeFixProvider. But there is still work to do. Accepting the suggested changes updates the type name and all references to that type in the solution. Add the following code as the last line in AnalyzeNode: You can check your progress by pressing F5 to run your analyzer. To install it you can run the following command in the … Now that you have your feet wet with Roslyn, let’s take a deeper dive into its API and see how we can create a simplistic dynamic mock at runtime. It no longer applies. Analyzer unit tests are a great tool when you know what code constructs should and shouldn't trigger your analyzer. Add the following string constant to your tests to represent that case: Then, add a data row for this test as shown in the snippet below: This test passes as well. It should look for a single local declaration that could be const but is not, like the following code: The first step is to find local declarations. Infact the project started internally at Microsoft a couple of years earlier. Finally, a new instance of the mock is created with a reference to the callback object (Lines 49-50). Consider the following test case string constant: The variable i can be made constant, but the variable j cannot. If you look at certain objects (like a SyntaxTree) in your Autos window, you can see the tree (and its corresponding code) in the visualizer. This is a CTP and trying to gain any insight into performance numbers you gather is suspect at best. The mock structure you’re goin g to create is fairly simple compared with some of the frameworks that currently exist in the .NET world. You can click on the light bulb displayed with the warning to see the suggested changes. When your analyzer detects a violation, it creates a diagnostic object that Visual Studio uses to notify the user of the violation. Immediately before the first foreach loop, call context.SemanticModel.GetTypeInfo() to retrieve detailed information about the declared type of the local declaration: Then, inside your foreach loop, check each initializer to make sure it's convertible to the variable type. If a declaration could be constant, your analyzer will create and report a diagnostic. Roslyn is deployed as a NuGet package. Referencing additional class library assemblies. Roslyn is a set of compilers, code analysis API for.NET languages. Let’ s use a simple example to illustrate how mocks are used. You look to see if the callback object has a method that matches the signature of the interface method. You're almost done. The template creates an analyzer that reports a warning on each type declaration where the type name contains lowercase letters, as shown in the following figure: The template also provides a code fix that changes any type name containing lower case characters to all upper case. The last thing you need to look at are the trees that Roslyn produces. Call the GetDeclaredSymbol extension method to retrieve the ILocalSymbol for the variable and check that it isn't contained with the DataFlowAnalysis.WrittenOutside collection of the data flow analysis. This code fix is already wired up to the Diagnostic ID produced by your diagnostic analyzer, but it doesn't yet implement the right code transform. The mock is typically used in unit testing scenarios, where a developer will use a mock instead of an object that does a number of long -running or complex calculations. It’s slower, but you won’t have to deal with any uninstallation issues that a CTP may have. The barrier to entry to perform powerful metaprogramming-based implementations is much lower with Roslyn. You'll perform some semantic analysis using the SyntaxNodeAnalysisContext. So, if you install VS2015 you´re already using Roslyn. In the MakeConstAnalyzerAnalyzer.Initialize method, find the line that registers the action on symbols: After that change, you can delete the AnalyzeSymbol method. With all of this in place, you can now create a mock using the ITest and TestCallback classes like this: When this code executes, the result will contain a random integer value. Next, check the declaration for any const modifiers. Generally speaking, a mock is an object that can stand in place of another object. Create a new document by replacing the existing declaration with the new declaration. Roslyn is the open-source implementation of both the C# and Visual Basic compilers with an API surface for building code analysis tools. Return to CodeFixProvider.cs. Then, you only need to define a couple string constants for each new test. For example, consider the following code: In the code above, x is assigned a constant value and is never modified. In other words, const string s = "abc" is legal, but const object s = "abc" is not. If Emit() wasn’t successful, you can check the Diagnostic property to find out what isn’t correct in your code (Lines 39-47). By compiling C# at runtime, you can implement anything you want at the abstraction level you always write at. If so, it is legal to declare, In the second Visual Studio instance, create a new C# Console Application project and add, Finally, add another local variable that uses the, Move the editor caret over the squiggly underline and press. Declare that method using the following code: Change the Category to "Usage" in MakeConstAnalyzer.cs as shown in the following code: It's time to write the first version of the AnalyzeNode method. The actions represent code changes that should trigger your analyzer to examine code for violations. The rules you implement can be anything from code structure to coding style to naming conventions and more. The semantic checks are in a separate loop because it has a greater impact on performance. The first thing you want to do is create a string that represents th e structure of the class you want to dynamically create at runtime: Each mock needs a new type name ({0}), the interface it’s implementing {1}, a reference to the callback object ({2}) , and a list of interface methods with an implementation based on the methods that exist in the callback object ({3}). When Visual Studio detects code edits that match a registered action, it calls your analyzer's registered method. There are multiple ways to list the names of every variable declared in the loaded code. Visual Studio calls analyzers while the user is writing code. Earlier the compiler was written in C/C++. To be fair, Roslyn can compile code files and generate assemblies—it has to if it’s going to replace csc.exe. You have the ability to create a C#-based mock. The key aspect to notice is the way the implementation is done. Congratulate yourself by running your finished analyzer. Description. Next, you’ll see how you can compile this with Roslyn. DiagnosticAnalyzer.Initialize(AnalysisContext), CodeFixProvider.RegisterCodeFixesAsync(CodeFixContext). Open the Resources.resx file for the MakeConst analyzer project. Be careful to first remove any leading trivia from the first token of the declaration statement and attach it to the const token. Add a source string constant for that condition: In addition, reference types are not handled properly. Otherwise, you return the default value of the interface method’s return type if it’s not void (Lines 27-36). Windows Communication Foundation has become an integral part of many .NET based solutions, enabling highly customizable messaging across distributed environments. Installation instructions - Visual Studio Installer. The default startup project is the VSIX project. You'll address these cases by working with the unit test library written by the template. No other node type triggers a call to your AnalyzeNode method. This is time-consuming and brittle. But the point is, Roslyn brings code analysis and manipulation to a much higher level than what was ever available before. As a general rule, analyzers should exit as quickly as possible, doing minimal work. There’s a lot more to mocks and unit testing than what we’ve presented in this section. Via the package called Microsoft.CodeAnalysis.CSharp.Scripting, you get access to what I like to call high level scripting APIs of the C# compiler. But, you can also use metaprogramming techniques to sy nthesize a class at runtime that does this for you. Nous essaieront de couvrir tout ce qu’il y a à savoir sur le "App store" : les types de licences, les modèles de reven. Part 1: Installing Roslyn. When you have finished, the resource editor should appear as follow figure shows: The remaining changes are in the analyzer file. The template also creates a unit test project for you. The first step is to create a new C# Analyzer with code fix project. In this tutorial, you'll visit syntax nodes looking for local declarations, and see which of those have constant values. That enables you to differentiate the visual settings in the two copies of Visual Studio. The following code looks for any const modifiers on the local declaration: Finally, you need to check that the variable could be const. Next, replace TestMethod2 with this test that ensures a diagnostic is raised and a code fix applied for the source code fragment: The preceding code also made a couple changes to the code that builds the expected diagnostic result. “In order to understand recursion, one must first understand recursion.”, Developer Fusion - The global developer community for .NET and Java programmers, http://hibernatingrhinos.com/open-source/rhino-mocks, Apt Windows: Let’s Get Chocolatey! Note that the dynamic assembly is lazily created (Lines 53-63). You can learn more in the article that covers semantic models. Now, let’s see the code that’s generated to create a meaningful object description from ToString() : You’re creating C# code as the output and not something like IL in a dynamic method. To fix the first bug, first open DiagnosticAnalyzer.cs and locate the foreach loop where each of the local declaration's initializers are checked to ensure that they're assigned with constant values. Also, since this is a CTP, yo u may not want to run this on your main installation of VS 2010; a safer bet is to create a virtual PC and work with Roslyn there. In the second Visual Studio instance that you just started, create a new C# Console Application project (either .NET Core or .NET Framework project will work -- analyzers work at the source level.) It exposes the syntax trees the compilers use to understand Visual Basic and C# programs. The following snippet defines both the code that raises the diagnostic, and the code after the fix has been applied: Finally, if a variable is declared with the var keyword, the code fix does the wrong thing and generates a const var declaration, which is not supported by the C# language. For the first step, you can rework these tests as data driven tests. To do so naively, take all … If you want to suggest a new feature for the C# or Visual Basic languages go here: dotnet/csharplang for C# specific issues Next, you create a ScriptEngine object, passing it the assembly references it needs to know about as well as any namespaces. roslyn Syntax Tree. Roslyn is open source .Net compiler in which the C++ code is replaced. Figure 7 shows the debug visualizer that is a representation of the mock code as a tree: Figure 7 The Roslyn syntax debugging visualizer. Add a declaration for MakeConstAsync like the following code: Your new MakeConstAsync method will transform the Document representing the user's source file into a new Document that now contains a const declaration. As you can imagine, these trees are rich and complex—in fact, when you install Roslyn, you get a couple of visualizers to help you see the tree. You saw how Roslyn provides you with a rich view of your code with parsers that provide tokens and trees. The template creates the initial DiagnosticAnalyzer class, in the MakeConstAnalyzer.cs file. A code fix defines an edit that addresses the reported issue. It allows us to write code which parses a source file and It is easy for us to modify source code. Notice that AnalyzeNode has red squiggles under it. Explore the analyzer template. Why not write for us? The course will focus on the rationale for building the .NET Compiler Platform, its overall architecture, and the various APIs exposed to analyze and manipulate C# and Visual Basic programs. You iterate through each method on the callback object. This tutorial creates an analyzer that finds local variable declarations that could be declared using the const modifier but are not. Press F5 to start the VSIX project. Open MakeConstAnalyzer.cs in Visual Studio. That project contains two tests. Now that you've seen the initial analyzer in action, close the second Visual Studio instance and return to your analyzer project. Introduction. connection lost, reconnecting… Code This initial analyzer shows two important properties of every analyzer. Scripting backends. The caller will use a class with methods that match the signature of the methods in the interface that you want to handle in the test. The analyzer with code fix template creates three projects: one contains the analyzer and code fix, the second is a unit test project, and the third is the VSIX project. The code you just added references an AnalyzeNode method that hasn't been declared. Change the title string to "Make constant": Next, delete the MakeUppercaseAsync method. Curated list of Roslyn books, tutorials, open source projects, analyzers, code fixes, refactorings, and source generators. Add the following code to the end of the AnalyzeNode method: The code just added ensures that the variable isn't modified, and can therefore be made const. Hopefully, once Roslyn is officially released, these frameworks will spend time updating their engines to use the Roslyn API to generate their mocks. var workspace = Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.Create (); var project = await workspace.OpenProjectAsync (projectFilePath); var compilation = await project.GetCompilationAsync (); foreach (var diagnostic in compilation.GetDiagnostics () .Where (d => d.Severity == … Let’s go through a quick example to see what the generated code looks like. Before the closing curly brace of the first foreach loop, add the following code to check the type of the local declaration when the constant is a string or null. Every diagnostic analyzer must derive from the. Unit tests for analyzers are much quicker than testing them interactively with Visual Studio. Even before its first final release in Visual Studio 2015, it started to mean a lot more than just a new compiler. We will explain what is Roslyn, what you can use it for and show practical examples on transforming C# code. For Source Code, Sample Chapters, the Author Forum and other resources, go to http://www.manning.com/hazzard/. Learn Roslyn Now is a blog series that explores Microsoft’s Roslyn compiler API. In order to create a Roslyn Analyzer project, you need to install the .NET Compiler Platform SDK via the Visual Studio Installer. The end result may look simple, but step back for a moment and think about what you just did. Welcome to the .NET Compiler Platform ("Roslyn") Roslyn provides open-source C# and Visual Basic compilers with rich code analysis APIs. For example, assume a Microsoft.CodeAnalysis.Compilation instance named compilation has been configured. Tutorial: Write your first analyzer and code fix Prerequisites. While you are refactoring, rename both methods to better names. If you’re interested in getting a deeper dive into unit testing, please check out “The Art of Unit Testing” ( http://manning.com/osherove/) and “Dependency Injection in .NET” (http://manning.com/seemann/). This starts a second instance of Visual Studio that has loaded your new analyzer. Here I would like to go over more about what I learned while building that visual studio extension, in particular sharin… The CallMe() method calls Callback on the TestCallback object as the signature matches. Along the way, you've learned many of the code APIs that are part of the .NET Compiler Platform SDK (Roslyn APIs). Add the following code to AnalyzeNode in MakeConstAnalyzer.cs: This cast always succeeds because your analyzer registered for changes to local declarations, and only local declarations. Your analyzer already handles one of those tests, the case where a variable is assigned after being initialized. In RegisterCodeFixesAsync, change the ancestor node type you're searching for to a LocalDeclarationStatementSyntax to match the diagnostic: Next, change the last line to register a code fix. .NET Compiler Platform ("Roslyn"): Analyzers and the Rise of Code-Aware Libraries. TestMethod1 shows the typical format of a test that analyzes code without triggering a diagnostic. Your semantic analysis examined a single variable declaration. It enables building code analysis tools with the same APIs that are used by Visual Studio. Implement the code fix to accept recommendations. This works fine if you add const to the declarations starting with i, then j and finally k. But, if you add the const modifier in a different order, starting with k, your analyzer creates errors: k can't be declared const, unless i and j are both already const. A syntax tree is a data structure used by the C# and Visual Basic compilers to understand C# and Visual Basic programs. After these changes, you get red squiggles only on the first two variables. Now, whenever a developer needs to test a Person object, they also need to ensure that the service is up and running and will return the expected data. It's much faster than repeatedly opening a second copy of Visual Studio. Optionally, an analyzer can also provide a code fix that represents a modification to the user's source code. That means making sure it is never assigned after it is initialized. Add the following using directive to the top of the file: The final step is to make your edit. The .NET Compiler Platform provides the framework for running analysis as developers are writing code, and all the Visual Studio UI features for fixing code: showing squiggles in the editor, populating the Visual Studio Error List, creating the "light bulb" suggestions and showing the rich preview of the suggested fixes. This is needed for our scripting environment so it can reference the object that you’ve been given in @this. The second check guarantees that the initializer is a constant. TestMethod2 shows the pattern for reporting a diagnostic and running the code fix. A Microsoft.CodeAnalysis.SemanticModel represents all of semantic information in a single source file. With Roslyn, you can easily create dynamic code that does complex activities. Each declared variable needs to have an initializer. Replace the line that declares and initializes newLocal with the following code. Once Create() is done, you can emit the results into a dynamic module. Syntax trees are produced by the same parser that runs when a project is built or a developer hits F5. This is necessary because, if you want to retain code formatting as you change it, you need to know what kind of whitespace exists in the document (and how much of it). The code doesn’t care how the class that implements IAddressService works; it just cares about the contract that the interface specifies. An analyzer is a way to perform source code analysis and report a problem to the user. The only constant value allowed for a reference type is null, except in this case of System.String, which allows string literals. In Implementing Adapter Pattern and Imitating Multiple Inheritance in C# using Roslyn based VS Extension Wrapper Generatorarticle I describe building a VS 2015 preview Roslyn based extension for generating class member wrappers. The template also shows the basic features that are part of any analyzer: You register actions in your override of DiagnosticAnalyzer.Initialize(AnalysisContext) method. In this course, we'll explore the .NET Compiler Platform, codenamed "Roslyn". Let’s see how you can use Roslyn to create a mock at runtime. Figure 1 lays out the flow and interaction between these parts so you can see at a higher level how they work together to run your dynamic code. compress css and generate sql connection strings. The first step is to update the registration constants and Initialize method so these constants indicate your "Make Const" analyzer. Find out more. Open the MakeConstCodeFixProvider.cs file added by the template. You’ll compile the code and create an instance of the mock, passing that back to the caller. The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs.
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