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CSharpGuidelinesAnalyzer/docs/Overview.md at master · bkoelman/CSharpGuidelinesAnalyzer

Implementation overview

The list below describes per rule what its analyzer reports on.

Category: Class Design

AV1000: A class or interface should have a single purpose

This analyzer reports when a type has the word "And" in its name.

This analyzer reports when:

  • the name of a static class does not end in "Extensions"
  • a static class whose name ends in "Extensions" contains a public or internal non-extension method.

AV1010: Don't suppress compiler warnings using the new keyword

This analyzer reports when a member has the new modifier in its signature.

Category: Member Design

AV1115: A property, method or local function should do only one thing

This analyzer reports when a member has the word "And" in its name.

AV1130: Return an IEnumerable<T> or ICollection<T> instead of a concrete collection class

This analyzer reports when the return type of a public or internal method implements IEnumerable and is changeable (for example: List<string> or ICollection<int>). Instead, return IEnumerable<T>, IAsyncEnumerable<T>, IQueryable<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, IReadOnlySet<T>, IReadOnlyDictionary<TKey, TValue> or an immutable collection.

AV1135: Properties, arguments and return values representing strings or collections should never be null

This analyzer reports when null is returned from a method, local function, lambda expression or property getter which has a return type of string, collection or task.

Category: Miscellaneous Design

AV1210: Don't swallow errors by catching generic exceptions

This analyzer reports when a handler catches Exception, SystemException or ApplicationException without a when filter.

AV1225: Use a protected virtual method to raise each event

This analyzer reports when an event is raised:

  • not from a method (for example, from a lambda expression or local function)
  • from a method that is not protected and virtual
  • from a method whose name does not match the pattern On{EventName}, for example: OnValueChanged.

AV1235: Don't pass null as the sender argument when raising an event

This analyzer reports when:

  • 'sender' argument is null when raising a non-static event
  • 'args' argument is null when raising an event.

AV1250: Evaluate the result of a LINQ expression before returning it

This analyzer reports when the return type of a public method is IEnumerable or IEnumerable<T> and it returns:

  • the result of a method call that uses deferred execution (for example: Where, Select, Concat)
  • the result of a query (LINQ expression)
  • an expression of type IQueryable or IQueryable<T>.

Category: Maintainability

AV1500: Methods should not exceed 7 statements

This analyzer reports when a method body (such as a method, property getter or local function) contains more than 7 statements.

Note: This rule can be customized using a configuration file by setting MaxStatementCount to a value in range 0-255.

AV1502: Avoid conditions with double negatives

This analyzer reports when the logical not operator is applied on an argument that has the word "No" or "Not" in its name.

AV1505: Name assemblies after their contained namespace

This analyzer reports when:

  • a namespace does not match with the assembly name
  • a type is declared in a namespace that does not match with the assembly name
  • a type is not declared in a namespace.

AV1506: Name a source file to the type it contains

This analyzer reports when:

  • a file is not named using pascal casing
  • a file name contains an underscore
  • a file name includes generic arity.

AV1507: Limit the contents of a source code file to one type

This analyzer reports when a file contains multiple non-nested types, unless they only differ by generic arity.

AV1522: Assign each variable in a separate statement

This analyzer reports when multiple properties, fields, parameters or variables are assigned in a single statement, except when using out variables, is-patterns or deconstruction into tuples.

AV1530: Don't change a loop variable inside a for loop

This analyzer reports when a for loop variable is written to in the loop body.

This analyzer reports when for, foreach, while or do-while loops are nested.

AV1535: Always add a block after the keywords if, else, do, while, for, foreach and case

This analyzer reports when a case or default clause in a switch statement does not have a block. The other keywords can be configured using Resharper.

AV1536: Always add a default block after the last case in a switch statement

This analyzer reports when a non-exhaustive switch statement on a (nullable) bool or (nullable) non-flags enum type does not have a default clause.

AV1537: Finish every if-else-if statement with an else clause

This analyzer reports when an if-else-if construct does not end with an unconditional else clause.

AV1551: Call the more overloaded method from other overloads

This analyzer reports when:

  • an overloaded method does not call another overload (unless it is the longest in the group)
  • the longest overloaded method (the one with the most parameters) is not virtual
  • the order of parameters in an overloaded method does not match with the parameter order of the longest overload.

AV1553: Only use optional parameters to replace overloads

This analyzer reports when an optional parameter of type string, collection or task has default value null.

AV1554: Do not use optional parameters in interface methods or their concrete implementations

This analyzer reports when an interface method or an abstract/virtual/override method contains an optional parameter.

AV1555: Avoid using named arguments

This analyzer reports when a named argument is used, unless the parameter type is bool or bool?.

AV1561: Don't declare signatures with more than 3 parameters

This analyzer reports when a method, constructor, local function, indexer or delegate:

  • declares more than three parameters
  • declares a tuple parameter
  • returns a tuple with more than 2 elements.

Note: This rule can be customized using a configuration file by setting MaxParameterCount and/or MaxConstructorParameterCount to a value in range 0-255. When MaxConstructorParameterCount is omitted, the value from MaxParameterCount (or its default) is used for constructors.

AV1562: Don't use ref or out parameters

This analyzer reports when:

  • a parameter is declared as ref
  • a parameter is declared as out, unless the containing method name starts with "Try".

AV1564: Avoid signatures that take a bool parameter

This analyzer reports when a public or internal member declares a parameter of type bool or bool?.

AV1568: Don't use parameters as temporary variables

This analyzer reports when a by-value (not ref, in or out) parameter is written to.

AV1580: Write code that is easy to debug

This analyzer reports using nested method calls.

Category: Naming

AV1704: Don't include numbers in variables, parameters and type members

This analyzer reports when a digit occurs in the name of a type, member, local function, parameter, tuple element or variable.

AV1706: Don't use abbreviations

This analyzer reports when the name of a type, member, local function, parameter, tuple element or variable consists of a single letter or contains an abbreviation like "Btn", "Ctrl", "Frm", "Chk", "Str" etc.

AV1708: Name types using nouns, noun phrases or adjective phrases

This analyzer reports when a type name contains the term "Utility", "Utilities", "Facility", "Facilities", "Helper", "Helpers", "Common" or "Shared".

AV1710: Don't repeat the name of a class or enumeration in its members

This analyzer reports when a member name contains the name of its containing type.

AV1711: Name members similarly to members of related .NET Framework classes

This analyzer reports when a member is named "AddItem", "Delete" or "NumberOfItems". See also CA1726.

AV1712: Avoid short names or names that can be mistaken for other names

This analyzer reports when a variable or parameter is named "b001", "lo", "I1" or "lOl".

AV1715: Properly name properties

This analyzer reports when a public or internal (nullable) boolean member or parameter name does not start with a word like "is", "has", "can" etc.

AV1738: Prefix an event handler with "On"

This analyzer reports when the name of an event handler method does not match the pattern {TargetName}On{EventName}, for example: OkButtonOnClick.

AV1739: Use an underscore for irrelevant lambda parameters

This analyzer reports when an unused lambda parameter name does not consist solely of underscores.

AV1745: Group extension methods in a class suffixed with Extensions

This analyzer reports when all public and internal methods of a static class are extension methods, but its name does not end with "Extensions".

AV1755: Postfix asynchronous methods with Async or TaskAsync

This analyzer reports when the name of an async method does not end with "Async".

Category: Performance

AV1840: Await ValueTask and ValueTask<T> directly and exactly once

This analyzer reports when an expression of type ValueTask or ValueTask<T> is being assigned or used as argument without await.

Category: Framework

AV2202: Prefer language syntax over explicit calls to underlying implementations

This analyzer reports when:

  • the HasValue property of a nullable value type is used to check for null
  • a comparison with a nullable value type contains a redundant null check.

AV2210: Build with the highest warning level

This analyzer reports when warnings are not treated as errors in the build settings.

Note: this analyzer requires Full Solution Analysis enabled.

AV2220: Avoid LINQ query syntax for simple expressions

This analyzer reports when a query (LINQ expression) can be changed into a single method call.

AV2230: Only use the dynamic keyword when talking to a dynamic object

This analyzer reports when a statically typed expression is implicitly converted to dynamic, unless the source type is object or ObjectHandle.

AV2235: Favor async/await over Task continuations

This analyzer reports when Task.ContinueWith is called.

Category: Documentation

AV2305: Document all public, protected and internal types and members

This analyzer reports (in addition to what the C# compiler reports) when compiling with documentation comments enabled and:

  • an internal type has no XML documentation comments
  • an internal member has no XML documentation comments
  • a public member in an internal type has no XML documentation comments
  • a parameter of an internal member has no XML documentation comments.

This analyzer reports when a comment is found inside a method body, except when it is a Resharper suppression, language injection or formatter configuration comment.

AV2318: Don't use comments for tracking work to be done later

This analyzer reports when a comment starts with the word "TODO".

Category: Layout

This analyzer reports when a #region directive is found.