ManageIQ/manageiq

Checks for rescue blocks targeting the Exception class.

Example:

# bad

begin
  do_something
rescue Exception
  handle_exception
end

Example:

# good

begin
  do_something
rescue ArgumentError
  handle_exception
end

Checks that there are no repeated bodies within if/unless, case-when, case-in and rescue constructs.

With IgnoreLiteralBranches: true, branches are not registered as offenses if they return a basic literal value (string, symbol, integer, float, rational, complex, true, false, or nil), or return an array, hash, regexp or range that only contains one of the above basic literal values.

With IgnoreConstantBranches: true, branches are not registered as offenses if they return a constant value.

Example:

# bad
if foo
  do_foo
  do_something_else
elsif bar
  do_foo
  do_something_else
end

# good
if foo || bar
  do_foo
  do_something_else
end

# bad
case x
when foo
  do_foo
when bar
  do_foo
else
  do_something_else
end

# good
case x
when foo, bar
  do_foo
else
  do_something_else
end

# bad
begin
  do_something
rescue FooError
  handle_error
rescue BarError
  handle_error
end

# good
begin
  do_something
rescue FooError, BarError
  handle_error
end

Example: IgnoreLiteralBranches: true

# good
case size
when "small" then 100
when "medium" then 250
when "large" then 1000
else 250
end

Example: IgnoreConstantBranches: true

# good
case size
when "small" then SMALL_SIZE
when "medium" then MEDIUM_SIZE
when "large" then LARGE_SIZE
else MEDIUM_SIZE
end

Do not define constants within a block, since the block's scope does not isolate or namespace the constant in any way.

If you are trying to define that constant once, define it outside of the block instead, or use a variable or method if defining the constant in the outer scope would be problematic.

For meta-programming, use const_set.

Example:

# bad
task :lint do
  FILES_TO_LINT = Dir['lib/*.rb']
end

# bad
describe 'making a request' do
  class TestRequest; end
end

# bad
module M
  extend ActiveSupport::Concern
  included do
    LIST = []
  end
end

# good
task :lint do
  files_to_lint = Dir['lib/*.rb']
end

# good
describe 'making a request' do
  let(:test_request) { Class.new }
  # see also `stub_const` for RSpec
end

# good
module M
  extend ActiveSupport::Concern
  included do
    const_set(:LIST, [])
  end
end

Example: AllowedMethods: ['enums'] (default)

# good

# `enums` for Typed Enums via `T::Enum` in Sorbet.
# https://sorbet.org/docs/tenum
class TestEnum < T::Enum
  enums do
    Foo = new("foo")
  end
end

Checks that there are no repeated bodies within if/unless, case-when, case-in and rescue constructs.

With IgnoreLiteralBranches: true, branches are not registered as offenses if they return a basic literal value (string, symbol, integer, float, rational, complex, true, false, or nil), or return an array, hash, regexp or range that only contains one of the above basic literal values.

With IgnoreConstantBranches: true, branches are not registered as offenses if they return a constant value.

Example:

# bad
if foo
  do_foo
  do_something_else
elsif bar
  do_foo
  do_something_else
end

# good
if foo || bar
  do_foo
  do_something_else
end

# bad
case x
when foo
  do_foo
when bar
  do_foo
else
  do_something_else
end

# good
case x
when foo, bar
  do_foo
else
  do_something_else
end

# bad
begin
  do_something
rescue FooError
  handle_error
rescue BarError
  handle_error
end

# good
begin
  do_something
rescue FooError, BarError
  handle_error
end

Example: IgnoreLiteralBranches: true

# good
case size
when "small" then 100
when "medium" then 250
when "large" then 1000
else 250
end

Example: IgnoreConstantBranches: true

# good
case size
when "small" then SMALL_SIZE
when "medium" then MEDIUM_SIZE
when "large" then LARGE_SIZE
else MEDIUM_SIZE
end

Checks that there are no repeated bodies within if/unless, case-when, case-in and rescue constructs.

With IgnoreLiteralBranches: true, branches are not registered as offenses if they return a basic literal value (string, symbol, integer, float, rational, complex, true, false, or nil), or return an array, hash, regexp or range that only contains one of the above basic literal values.

With IgnoreConstantBranches: true, branches are not registered as offenses if they return a constant value.

Example:

# bad
if foo
  do_foo
  do_something_else
elsif bar
  do_foo
  do_something_else
end

# good
if foo || bar
  do_foo
  do_something_else
end

# bad
case x
when foo
  do_foo
when bar
  do_foo
else
  do_something_else
end

# good
case x
when foo, bar
  do_foo
else
  do_something_else
end

# bad
begin
  do_something
rescue FooError
  handle_error
rescue BarError
  handle_error
end

# good
begin
  do_something
rescue FooError, BarError
  handle_error
end

Example: IgnoreLiteralBranches: true

# good
case size
when "small" then 100
when "medium" then 250
when "large" then 1000
else 250
end

Example: IgnoreConstantBranches: true

# good
case size
when "small" then SMALL_SIZE
when "medium" then MEDIUM_SIZE
when "large" then LARGE_SIZE
else MEDIUM_SIZE
end

Checks for the use of a return with a value in a context where the value will be ignored. (initialize and setter methods)

Example:

# bad
def initialize
  foo
  return :qux if bar?
  baz
end

def foo=(bar)
  return 42
end

Example:

# good
def initialize
  foo
  return if bar?
  baz
end

def foo=(bar)
  return
end

Checks for operators, variables, literals, lambda, proc and nonmutating methods used in void context.

Example: CheckForMethodsWithNoSideEffects: false (default)

# bad
def some_method
  some_num * 10
  do_something
end

def some_method(some_var)
  some_var
  do_something
end

Example: CheckForMethodsWithNoSideEffects: true

# bad
def some_method(some_array)
  some_array.sort
  do_something(some_array)
end

# good
def some_method
  do_something
  some_num * 10
end

def some_method(some_var)
  do_something
  some_var
end

def some_method(some_array)
  some_array.sort!
  do_something(some_array)
end

Checks for rescue blocks with no body.

Example:

# bad
def some_method
  do_something
rescue
end

# bad
begin
  do_something
rescue
end

# good
def some_method
  do_something
rescue
  handle_exception
end

# good
begin
  do_something
rescue
  handle_exception
end

Example: AllowComments: true (default)

# good
def some_method
  do_something
rescue
  # do nothing
end

# good
begin
  do_something
rescue
  # do nothing
end

Example: AllowComments: false

# bad
def some_method
  do_something
rescue
  # do nothing
end

# bad
begin
  do_something
rescue
  # do nothing
end

Example: AllowNil: true (default)

# good
def some_method
  do_something
rescue
  nil
end

# good
begin
  do_something
rescue
  # do nothing
end

# good
do_something rescue nil

Example: AllowNil: false

# bad
def some_method
  do_something
rescue
  nil
end

# bad
begin
  do_something
rescue
  nil
end

# bad
do_something rescue nil

Checks that there are no repeated bodies within if/unless, case-when, case-in and rescue constructs.

With IgnoreLiteralBranches: true, branches are not registered as offenses if they return a basic literal value (string, symbol, integer, float, rational, complex, true, false, or nil), or return an array, hash, regexp or range that only contains one of the above basic literal values.

With IgnoreConstantBranches: true, branches are not registered as offenses if they return a constant value.

Example:

# bad
if foo
  do_foo
  do_something_else
elsif bar
  do_foo
  do_something_else
end

# good
if foo || bar
  do_foo
  do_something_else
end

# bad
case x
when foo
  do_foo
when bar
  do_foo
else
  do_something_else
end

# good
case x
when foo, bar
  do_foo
else
  do_something_else
end

# bad
begin
  do_something
rescue FooError
  handle_error
rescue BarError
  handle_error
end

# good
begin
  do_something
rescue FooError, BarError
  handle_error
end

Example: IgnoreLiteralBranches: true

# good
case size
when "small" then 100
when "medium" then 250
when "large" then 1000
else 250
end

Example: IgnoreConstantBranches: true

# good
case size
when "small" then SMALL_SIZE
when "medium" then MEDIUM_SIZE
when "large" then LARGE_SIZE
else MEDIUM_SIZE
end

Checks for the presence of constructors and lifecycle callbacks without calls to super.

This cop does not consider method_missing (and respond_to_missing?) because in some cases it makes sense to overtake what is considered a missing method. In other cases, the theoretical ideal handling could be challenging or verbose for no actual gain.

Autocorrection is not supported because the position of super cannot be determined automatically.

Object and BasicObject are allowed by this cop because of their stateless nature. However, sometimes you might want to allow other parent classes from this cop, for example in the case of an abstract class that is not meant to be called with super. In those cases, you can use the AllowedParentClasses option to specify which classes should be allowed in addition to Object and BasicObject.

Example:

# bad
class Employee < Person
  def initialize(name, salary)
    @salary = salary
  end
end

# good
class Employee < Person
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
Employee = Class.new(Person) do
  def initialize(name, salary)
    @salary = salary
  end
end

# good
Employee = Class.new(Person) do
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
class Parent
  def self.inherited(base)
    do_something
  end
end

# good
class Parent
  def self.inherited(base)
    super
    do_something
  end
end

# good
class ClassWithNoParent
  def initialize
    do_something
  end
end

Example: AllowedParentClasses: [MyAbstractClass]

# good
class MyConcreteClass < MyAbstractClass
  def initialize
    do_something
  end
end

Checks for excessive nesting of conditional and looping constructs.

You can configure if blocks are considered using the CountBlocks option. When set to false (the default) blocks are not counted towards the nesting level. Set to true to count blocks as well.

The maximum level of nesting allowed is configurable.

Looks for expressions containing multiple binary operators where precedence is ambiguous due to lack of parentheses. For example, in 1 + 2 * 3, the multiplication will happen before the addition, but lexically it appears that the addition will happen first.

The cop does not consider unary operators (ie. !a or -b) or comparison operators (ie. a =~ b) because those are not ambiguous.

NOTE: Ranges are handled by Lint/AmbiguousRange.

Example:

# bad
a + b * c
a || b && c
a ** b + c

# good (different precedence)
a + (b * c)
a || (b && c)
(a ** b) + c

# good (same precedence)
a + b + c
a * b / c % d

Checks for rescue blocks targeting the Exception class.

Example:

# bad

begin
  do_something
rescue Exception
  handle_exception
end

Example:

# good

begin
  do_something
rescue ArgumentError
  handle_exception
end

Checks for useless method definitions, specifically: empty constructors and methods just delegating to super.

Safety:

This cop is unsafe as it can register false positives for cases when an empty constructor just overrides the parent constructor, which is bad anyway.

Example:

# bad
def initialize
  super
end

def method
  super
end

# good - with default arguments
def initialize(x = Object.new)
  super
end

# good
def initialize
  super
  initialize_internals
end

def method(*args)
  super(:extra_arg, *args)
end

Checks for assignments in the conditions of if/while/until.

AllowSafeAssignment option for safe assignment. By safe assignment we mean putting parentheses around an assignment to indicate "I know I'm using an assignment as a condition. It's not a mistake."

Safety:

This cop's autocorrection is unsafe because it assumes that the author meant to use an assignment result as a condition.

Example:

# bad
if some_var = true
  do_something
end

# good
if some_var == true
  do_something
end

Example: AllowSafeAssignment: true (default)

# good
if (some_var = true)
  do_something
end

Example: AllowSafeAssignment: false

# bad
if (some_var = true)
  do_something
end

Checks for rescue blocks targeting the Exception class.

Example:

# bad

begin
  do_something
rescue Exception
  handle_exception
end

Example:

# good

begin
  do_something
rescue ArgumentError
  handle_exception
end