Rules
General rules configuration is described here.
Rules are grouped by category to help you understand their purpose. Each rule has emojis denoting:
- ⚙️ - this rule is configurable
- 🛠 - some problems reported by this rule can be fixed by editor suggestions
- ⚠️ - this rule is deprecated and will be removed in the next major release
You can also suggest a rule!
Common 249 rules
Enforces named argument order in function and constructor invocations to be the same as corresponding named parameter declaration order.
Warns when a collection is accessed by a constant index inside a for loop.
Warns when a private member of another class is used.
Warns when an async function is invoked in non-async blocks.
Warns when a record type declaration contains fields with void, Never or Null.
Warns when a cascade expression is used after if null (??) binary expression without parentheses.
Warns when an expression is cast to an extension type.
Warns when a collection is checked for equality with another collection.
Avoid using collection methods with unrelated types, such as accessing a map of integers using a string key.
Warns then a binary expression has a boolean constant that either makes the resulting value always the same or does not affect it.
Warns when several conditions contradict each other.
Warns when an import/export directive contains a double slash.
Warns when a cascade expression has duplicate cascades.
Warns when a collection has duplicate collection elements.
Warns when a class or enum declaration has several constants with the same primitive values.
Warns when a file has multiple exports declarations with the same URI.
Warns when a final variable has the same initializer as another variable in scope.
Warns when a class has a mixin that is already present in that class's hierarchy.
Warns when a file has duplicate imports which differ only in name prefix.
Warns when a LogicalOrPattern or LogicalAndPattern contains duplicate patterns.
Warns when several switch cases have the same condition.
Warns when a test case has multiple test assertions with the same expression and expected value.
Warns when dynamic type is used as variable type in declaration, return type of a function, etc.
Warns when a collection literal in spread (...[]) has no elements.
Warns when a test group does not have any test cases.
Warns when both sides of a binary expression are the same.
Warns when a condition has excessive expressions.
Warns when an object pattern has an explicit field name.
Warns when a variable is declared with an explicit type that can be omitted.
Warns when a record type declaration contains a function type.
Warns when a Future is a target of the toString method or is used in an interpolation.
Warns when a generic type shadows an existing top-level (class, mixin, typedef or enum) declaration.
Warns when a try / catch has multiple catch blocks with the same body.
Warns when a return value of a method or function invocation or a class instance property access is not used.
Warns when an extension type declaration does not have the implements clause.
Warns when an entrypoint export is imported inside the library src folder.
Warns when an inferrable type argument can be removed without affecting the code.
Warns when a wildcard pattern has declaration keywords.
Warns when a file length (number of lines) exceeds the configured maximum.
Warns when Map's .keys.contains is used instead of containsKey.
Warns when a method that should be invoked is passed as tear-off.
Warns when Completer.completeError is called without providing a stack trace.
Warns when a enum constant is missing in a map declaration.
Warns when a string equals to a variable name that is available in the current scope but is not wrapped into an interpolation.
Configure a list of files that should have a corresponding test file.
Warns when an incorrect matcher or literal is used to verify the target expression.
Warns when a wildcard pattern is used in the wrong context.
Warns when a record declaration contains both named and positional fields.
Warns when multiple variable assignments are placed on the same line.
Warns when an if statement or conditional expression have a negated condition that can be inverted.
Warns when the representation field of an extension type is also an extension type.
Warns when a record type declaration contains a nested record type declaration.
Warns when a Stream type contains a Future or vice versa.
Warns when a switch expression contains another switch expression.
Warns when an exception class declaration has non-final fields.
Warns when non null assertion operator ! (or “bang” operator) is used for a property access or method invocation. The operator check works at runtime and it may fail and throw a runtime exception.
Warns when a toJson method references a non-encodable object.
Warns when an interpolation string contains a nullable value.
Warns when a parameter with the default value is marked as nullable.
Warns when the toString method is called on a nullable value.
Warns when an asynchronous function is used as an argument where a synchronous function is expected.
Warns when an invocation has an argument that matches the parameter's default value.
Warns when an object is used as an argument to its own method.
Warns when a record positional field is accessed via $.
Checks for redundant async in a method or function body.
Checks for else blocks that can be removed without changing semantics.
Warns when a record positional field has a name.
Warns when a @pragma('vm:prefer-inline') annotation has no effect.
Warns when a variable with the name that has only underscores (ex. _, __, etc.) is referenced.
Warns when an extension type exposes a member that renames an existing representation field member.
Suggests calling functions or methods with a void return type separately from the return statement.
Warns when a variable or a class instance field / property is assigned to itself.
Warns when a comparison has both sides exactly the same.
Warns when an extension declares a method with the name that is already used by the extension target.
Warns when a declaration name shadows another declaration with the same name in the current scope.
Checks for names within the scope that are very similar and thus confusing.
Warns when a getter overrides a field that is already passed to the super constructor.
Warns when a throw expression is called inside a catch block.
Warns when a thrown object does not implement toString.
Warns when a public top-level member (except the entrypoint) is declared inside a test file.
Warns when a late field is not assigned a value.
Warns when a stream subscription is not assigned to a variable.
Warns when an error from a Future inside a try / catch block might not be caught.
Warns when a break, continue, return or throw are used unconditionally in a for loop.
Warns when the @pragma annotation has an unknown value.
Warns when a .call() invocation is unnecessary and can be simplified.
Warns when a collection literal can be replaced by its first and only element.
Checks for unnecessary conditional expressions.
Suggests removing an unnecessary empty constructor for enum and class declarations.
Warns when a enum constant has an unnecessary empty argument list.
Suggests removing unnecessary extends clauses that match default values for classes and type parameters.
Warns when a return type of a declaration is unnecessary wrapped into a Future.
Warns when a getter provides access to an existing final field without any additional logic.
Warns when a return statement inside an if block is equal to the return statement after it.
Warns when a late variable is assigned in all code branches before use.
Warns when the return type of a function or a method is declared nullable, but the function or method always return non-nullable value.
Warns when a parent declaration is overridden by a declaration without an implementation.
Warns when a value is reassigned to a variable without using the initial value.
Warns when a return statement is unnecessary and can be removed.
Warns when a constructor has an unnecessary super invocation.
Warns about unnecessary usage of the is operator, and whereType and whereNotNull methods.
Warns about unnecessary use of the as operator and cast method.
Warns about unrelated usages of the is operator and whereType method.
Warns about unrelated usages of the as operator and cast method.
Warns when first, last, single, firstWhere, lastWhere, singleWhere or [] methods are used on Iterable or its subclasses.
Warns when the .reduce collection method is called on a potentially empty collection.
Warns when a variable is checked for non-nullable value, but is not used within the condition or then branch.
Warns when an assignment is not used in the subsequent statements.
Warns when a function or method declares unused generic types.
Warns when a newly created object is not being used.
Checks for unused parameters inside a function or method body.
Warns when a weak cryptographic algorithm (ex. md5 or sha1) is used.
Warns when a switch on the Enum value has a wildcard pattern case.
Warns when the configured method, field, constructor, or property name is used.
Warns when a literal value is on the left hand side in a binary expressions.
Checks that double literals should begin with 0. instead of just ., and should not end with a trailing 0.
Warns when a test or testWidgets name doesn't follow the configured pattern.
Warns when a function with nullable return type returns only nullvalue.
Warns when an invocation's declaration is annotated with @Throws() but the potential exception is not handled.
Warns when a getter or setter do not access at least one field with the name that matches the getter or setter name.
Warns when the file path in the test folder does not match the implementation file path in the lib folder.
Warns when a positional field name does not match a variable name on destructuring assignment.
Warns when a method or function declaration is missing the @useResult annotation.
Warns when a variable is declared in the outer block, but used only in the inner one.
Warns when a variable does not depend on the outer loop and can be moved out.
Warns when equal arguments are passed to a function or method invocation.
Warns when a if statement has duplicate conditions.
Warns when an if statement contains another if statement with the same condition.
Warns when a switch expression has cases with equal bodies.
Warns when if statement has equal then and else statements or conditional expression has equal then and else expressions.
Warns when number literals are used outside of named constants or variables.
Warns when string literals are used outside of named constants or variables.
Suggests adding abstract final to classes with only static members to avoid them being instantiated or being used in inheritance.
Warns when a collection's call chain can be rewritten to use .any() or .every() instead of .isEmpty or .isNotEmpty.
Recommends to use async/await syntax to handle a Future result instead of .then() invocation.
Suggests to prefix boolean variables, methods, fields and parameters with one of the configured prefixes.
Warns when a @pragma('vm:prefer-inline') annotation does not have a corresponding @pragma('dart2js:tryInline') annotation.
Warns when // ignore: comments are left without any additional description why this ignore is applied.
Recommends to use a conditional expression instead of assigning to the same thing or return statement in each branch of an if statement.
Suggests using .contains instead of .indexOf when checking for the presence of an element.
Warns when a field with a Function type does not matched the configured name or a field with a non-Function type matches the configured name.
Ensures a consistent name for the error parameter in catch, then, catchError, listen and handleError.
Warns when a for loop increments a wrong variable.
Warns when a declaration that returns a Future has an incorrect return type.
Warns when the callback handler name does not matched the configured one.
Warns when an identifier name length is very short or long.
Warns when a JSON object type cast is done in an unsafe way that will throw at runtime.
Warns when the setter parameter name does not match the configured one.
Warns when a declaration that returns a Stream has an incorrect return type.
Warns if the file within /test contains a main, but the file name doesn't end with _test.dart.
Warns when a declaration is missing or has an unnecessary @Throws() annotation.
Type name should only contain alphanumeric characters, start with an uppercase character and span between min-length and max-length characters in length.
Warns when a class with no non-final fields has a non-constant constructor declaration.
Since Dart 2.15 it's possible to use byName method on enum values prop instead of searching the value with firstWhere.
Warns when a Function type does not specify the return type and arguments.
Warns when a method that accepts type arguments has no arguments and no type arguments passed.
Warns when an inline callback is passed as an argument to a function or method invocation.
Suggests to convert a method that has no parameters and side-effects to a getter.
Warns when a method or a function returns a variable declared right before the return statement.
Warns when List.from() factory is used instead of List.of().
Warns when a file name does not match the class name.
Warns when a property access or a method invocation start with duplicated chains of other invocations / accesses inside a single function or method block.
Warns when a declaration has a boolean positional parameter.
Suggests converting positional parameters to named parameters when a declaration has a certain number of positional parameters.
Warns when a null check inside a collection literal can be replaced with a null-aware spread (...?).
Warns when a parent class implements hashCode and ==, but the child class does not implement them.
Warns when an if null (??) has a binary expression without parentheses.
Warns when a global constant does not start with a configured prefix.
Warns when an extension type has a public representation field.
Warns when an exception class declaration is not public.
Warns when a Future is returned from a try / catch block without an await.
Warns when several returns inside a function body can be replace with a single conditional expression.
Warns when a patterns check for non-nullability can be simplified.
Warns when a file contains more than one top-level declaration (class, mixin, extension, enum or extension type).
Warns when a more specific switch case is placed after a more general one.
Suggests to use static class member instead of global constants, variables and functions.
Suggests to use a switch statement or expression instead of conditionals with multiple enum values.
Suggests to use a switch statement or expression instead of conditionals with sealed class instances.
Warns when the second argument of an expect or expectLater is not a subclass of a Matcher.
Checks for a trailing comma for arguments, parameters, enum values and collections.
Warns when a variable is declared with the var keyword instead of a type.
Warns when the test name is not unique within the same test suite.
Warns when the @visibleForTesting annotation is applied to the class declaration.
Warns when a dynamic or Object type is used instead of a wildcard pattern.
Checks for unnecessary trailing commas for arguments, parameters, enum values and collections.
Flutter 40 rules
Warns when a class that matches the config does not declare a copyWith method.
Warns when an event listener is added but never removed.
Checks if all the parameters from the default constructor are included in the copyWith method.
Warns when an Image widget is wrapped into an Opacity widget.
Warns when context.dependOnInheritedWidgetOfExactType is transitively called from any invocation in initState.
Warns when a TextFormField, TextField or EditableText does not have at least one way to get the updated value.
Warns when an Image widget does not have a semanticLabel.
Warns when a Widget recursively uses itself.
Warns when a method or function returns a Widget or subclass of a Widget.
Warns when a ListView widget with shrinkWrap parameter is wrapped in a Column, Row or another ListView widget.
Warns when a Column, Row, Flex, Wrap, SliverList, SliverMainAxisGroup or SliverCrossAxisGroup widget has only one child.
Warns when a State has a constructor with non-empty body.
Warns when an instance that has a dispose method is not assigned to a variable.
Warns when a GestureDetector widget has no event handlers.
Warns when a StatelessWidget has an initialized final field.
Warns when a widget's State has unnecessary overrides.
Warns when setState is called inside initState, didUpdateWidget or build methods and when it is called from a sync method that is called inside those methods.
Warns when a StatefulWidget can be converted to a StatelessWidget.
Warns when a widget is wrapped in a Padding widget but has a padding setting by itself.
Warns when a RenderObject setter doesn't have an equality check for the new value.
Warns when an updateRenderObject method is absent or doesn't update all fields set in createRenderObject.
Warns when a widget state field is not disposed in dispose method.
Warns when a FloatingActionButton does not have a tooltip specified.
Warns when MediaQuery.of or MediaQuery.maybeOf are used over dedicated methods (ex. sizeOf).
Warns about inline callbacks in a widget tree and suggest to extract them to a widget method.
Suggests using for-loop in arguments that accept a list of widgets.
Warns when a file contains more than one widget.
Warns when a widget that returns a Sliver... widget does not have a Sliver prefix in its name.
Warns when a Column widget with only children parameter is wrapped in a SingleChildScrollView widget.
Warns when a widget or widget state have public members (fields, methods, etc.).
Checks that super calls in the initState and dispose methods are called in the correct order.
Warns when setState is called past an await point.
Provider 5 rules
Warns when a Provider.value returns a new instance instead of reusing an existing one.
Warns when a watch or select methods are used outside of the build method.
Warns when a provided class with a dispose method does not have this method called in the Provider dispose callback.
Warns when multiple nested Providers can be replaced with MultiProvider instead.
Bloc 6 rules
Warns when a Bloc has public methods except the overridden ones.
Warns when an async handler does not have isClosed check before dispatching an event after an async gap.
Warns when a BlocProvider / BlocListener / RepositoryProvider can be replace with a Multi version.
Riverpod 7 rules
Warns when a Notifier (or AsyncNotifier) member is called inside the build method.
Warns when a Notifier (or AsyncNotifier) has a non-empty constructor.
Warns when a ConsumerWidget has an unused ref and can be converted to a regular widget.
Warns when an instance with a dispose method created inside a provider does not have the dispose method called in ref.onDispose.
Equatable 2 rules
Warns when a field is not added to props getter of a class that extends Equatable or EquatableMixin.
Flame 4 rules
Warns when a Vector2 is created inside a Component's update method.
Warns when a late final variable is being initialized in the Component's onMount method.
Warns when a game is instantiated in a StatelessWidget build method.
Patrol 2 rules
Suggests using custom finders instead of find in Patrol tests.
Fake Async 1 rule
Get It 1 rule
Warns when a function is passed to registerSingleton.
Flutter Hooks 6 rules
Warns when hooks inside the build method or other hooks are called conditionally.
Warns when a hook is used outside the build method, other hooks or HookBuilder.
Warns when a hook widget or HookBuilder does not use hooks.
Firebase Analytics 2 rules
Warns when the event name does not comply with Firebase limitations.
Warns when the parameter name does not comply with Firebase limitations.
GetX 4 rules
Warns when GetX Rx primitives are instantiated inside the build method.
Warns when a widget state field is not disposed in the onClose method.
Checks that super calls in the onStart, onInit, onClose and onDelete methods are called in the correct order.
Pubspec 9 rules
pubspec-rules: config section.Warns when a pubspec file has the dependency_overrides section.
Warns when a dependency version is listed not with the caret syntax.
Warns when a dependency version is not specified as the exact version.
Warns when a package version does not match the semantic versioning approach.
Intl 6 rules
Warns when DateTime, values are formatted with toString instead of DateFormat.format().
Recommends to use ClassName_ClassMemberName pattern for Intl methods name argument.
Warns when int, num or double values are formatted with toString instead of NumberFormat.format().
Warns when an Intl method invoked without a description.
Warns when an Intl method invoked without an examples argument or has it incomplete.
Easy Localization 1 rule
Angular 3 rules
Warns when a @Component annotation has explicit false value for preserveWhitespace.
Enforces Angular @Component annotation arguments ordering.
Prefer setting changeDetection: ChangeDetectionStrategy.OnPush in Angular @Component annotations.