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.
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.
