A collection of static analyzers based on Roslyn that integrate with VS
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README.md

VSDiagnostics

A collection of code-quality analyzers based on the Roslyn compiler platform. This project aims to ensure code-quality as you type it in your editor rather than having to do this as a separate build-step. By performing static analysis while you're writing code, certain convention violations and hidden pitfalls can be avoided as early in the process as possible.

Get it from NuGet!

Build status Test status

Keep in mind that this project is under active development. If you encounter bugs, let us know!

What is an analyzer exactly?

With the release of Visual Studio 2015 RC, we also received the pretty much final implementation of the Diagnostics implementation. This SDK allows us to create our own diagnostics to help us write proper code that’s being verified against those rules in real-time: you don’t have to perform the verification at a separate build-step. What’s more is that we can combine that with a code fix: a shortcut integrated in Visual Studio that provides us a solution to what we determine to be a problem.

This might sound a little abstract but if you’ve been using Visual Studio (and/or Resharper) then you know what I mean: have you ever written your classname as class rather than Class? This is a violation of the C# naming conventions and visual studio will warn you about it and provide you a quickfix to turn it into a proper capitalized word. This is exactly the behaviour we can create and which is integrated seemlessly in Visual Studio.

Full text available on my blog.

What is available?

Currently these diagnostics are implemented:

Category Name Description
Arithmetic VSD0045 The operands of a divisive expression are both integers and result in an implicit rounding.
Async VSD0001 Asynchronous methods should end with the -Async suffix.
Async VSD0041 A non-async, non-Task method should not end with -Async.
Async VSD0064 Async methods should return a Task to make them awaitable.
Attributes VSD0002 An attribute should not have an empty argument list.
Attributes VSD0003 Gives an enum the [Flags] attribute.
Attributes VSD0004 A [Flags] enum its values are not explicit powers of 2
Attributes VSD0039 A [Flags] enum its values are not explicit powers of 2 and its values dont fit in the specified enum type.
Attributes VSD0005 The [Obsolete] attribute doesn't have a reason.
Attributes VSD0006 OnPropertyChanged() can use the [CallerMemberName] attribute to automatically pass the property name.
Exceptions VSD0007 An ArgumentException should use nameof() to refer to a variable.
Exceptions VSD0008 Verifies no NullReferenceException is caught.
Exceptions VSD0009 Verifies whether an ArgumentException is thrown with a message.
Exceptions VSD0010 Warns when an exception catch block is empty.
Exceptions VSD0011 Warns when an exception is rethrown in a way that it loses the stacktrace.
Exceptions VSD0012 Verifies whether a try-catch block does not defer all exception handling to a single Exception clause.
Exceptions VSD0052 An exception is thrown from an implicit operator.
Exceptions VSD0053 An exception is thrown from a property getter.
Exceptions VSD0054 An exception is thrown from a static constructor.
Exceptions VSD0055 An exception is thrown from a finally block.
Exceptions VSD0056 An exception is thrown from an equality operator.
Exceptions VSD0057 An exception is thrown from a Dispose method.
Exceptions VSD0058 An exception is thrown from a finalizer method.
Exceptions VSD0059 An exception is thrown from a GetHashCode() method.
Exceptions VSD0060 An exception is thrown from an Equals() method.
Exceptions VSD0065 A null object is attempted to get thrown.
General VSD0013 Changes an as expression to a cast.
General VSD0014 Changes a cast expression to as.
General VSD0015 A boolean expression comparing to false can be simplified.
General VSD0016 A boolean expression comparing to true can be simplified.
General VSD0017 The conditional operator shouldn't return redundant default options.
General VSD0018 The conditional operator shouldn't return redundant inverted default options.
General VSD0019 The condition is a constant (false) and thus unnecessary.
General VSD0020 The condition is a constant (true) and thus unnecessary.
General VSD0021 Inserts the default access modifier for a declaration.
General VSD0022 Detects usage of the goto keyword.
General VSD0023 Requires braces for if, else, for, foreach, while, do, using, lock, fixed and switch constructs.
General VSD0025 Implements the most common configuration of naming conventions.
General VSD0026 A public, internal or protected internal non-const, non-readonly field should be used as a property.
General VSD0027 Changes Nullable<T> to T?.
General VSD0028 Use the nameof() operator in conjunction with OnPropertyChanged.
General VSD0029 Simplify the expression using an expression-bodied member.
General VSD0030 A constructor is the same as a default constructor and can be removed.
General VSD0031 Use as/null instead of is/as.
General VSD0032 Use var instead of the explicit type.
General VSD0033 Use the built-in type alias instead of the concrete type.
General VSD0044 Add cases for missing enum members.
General VSD0043 An instance of type System.Random is created in a loop.
General VSD0046 Equals() and GetHashCode() must be implemented together.
General VSD0047 Implement elementary methods for a type used in a collection.
General VSD0048 A property with a private setter can become a read-only property instead.
General VSD0049 A switch is missing a default label.\
General VSD0052 Implement Equals() and GetHashCode() using existing fields and properties.
General VSD0063 A GetHashCode implementation refers to a mutable field.
General VSD0066 Recursively using an overloaded operator.
Strings VSD0034 Replaces an empty string literal with the more expressive string.Empty.
Strings VSD0035 Orders the arguments of a string.Format() call in ascending order according to index.
Strings VSD0042 A string.Format() call lacks arguments and will cause a runtime exception.
Structs VSD0036 Warns when a struct replaces this with a new instance.
Structs VSD0050 Structs should implement Equals(), GetHashCode(), and ToString().
Tests VSD0037 A test method should not end with -Test.
Tests VSD0038 Verifies whether a test method has the public modifier.
Tests VSD0062 A method might be missing a test attribute.

How do I use this?

Simply head over to NuGet and install it! If you don't immediately find it: make sure you're also looking through the NuGet V2 package source.

Can I request diagnostics?

Yes, you can! Create an issue and we'll take a look at your proposal.

What if I don't like a diagnostic?

Every diagnostic can be turned off for a single line or for the entire project. At most, you will have to ignore the diagnostic once. For this reason every diagnostic is turned on by default. In order to do so, right click on 'Analyzers' under your references and select 'Open Active Rule Set'. This presents you with the following window to configure which diagnostics should be turned on and their default severity. If you wish to do so, you can change the severity to a more strict or more forgiving setting.

What's on the roadmap?

Most things are filed as an issue so if you want the complete picture -- head over there. However in broad terms:

  • Supporting more C# 6 features to ease the transition
  • Implement diagnostics aimed at removing unused code
  • Create a website that gives more detailed information
  • Add user-configurable settings for each diagnostic
  • Introduce a Visual Studio extension so it doesn't have to be tied to the project
  • Introduce a command-line tool so it isn't tied to a Visual Studio instance

Can I contribute?

Definitely! Take a look at the open issues and see if there's anything that interests you. Submit your pull request and we'll take a look at it as soon as possible.

If you think you're going to make larger changes than a single implementation then we would ask you to get in contact with us first so we can discuss it and prevent unneeded work.

You'll need Visual Studio 2015 and the SDK to get started.

Where can I find more information about every diagnostic?

Release 2.0.0 will come with a website where we document every diagnostic including reasoning behind its implementation choices. In the meantime you can take a look at the tests that belong to each diagnostic to see what exact scenarios we have accounted for.

How can I get in contact?

You're always free to open an issue but if you would like something more direct you can drop by in the StackExchange chat channel where the main contributors reside or send an email to jer_vannevel@outlook.com.