jbender/motion-spec

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true

# Some documentation for Person
class Person
  # Some code
end

# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

This cop checks for missing top-level documentation of classes and modules. Classes with no body are exempt from the check and so are namespace modules - modules that have nothing in their bodies except classes, other modules, or constant definitions.

The documentation requirement is annulled if the class or module has a "#:nodoc:" comment next to it. Likewise, "#:nodoc: all" does the same for all its children.

Example:

# bad
class Person
  # ...
end

# good
# Description/Explanation of Person class
class Person
  # ...
end

This cop checks for missing top-level documentation of classes and modules. Classes with no body are exempt from the check and so are namespace modules - modules that have nothing in their bodies except classes, other modules, or constant definitions.

The documentation requirement is annulled if the class or module has a "#:nodoc:" comment next to it. Likewise, "#:nodoc: all" does the same for all its children.

Example:

# bad
class Person
  # ...
end

# good
# Description/Explanation of Person class
class Person
  # ...
end

This cop checks whether some constant value isn't a mutable literal (e.g. array or hash).

Example:

# bad
CONST = [1, 2, 3]

# good
CONST = [1, 2, 3].freeze

This cop checks for ambiguous operators in the first argument of a method invocation without parentheses.

Example:

# bad

# The `*` is interpreted as a splat operator but it could possibly be
# a `*` method invocation (i.e. `do_something.*(some_array)`).
do_something *some_array

Example:

# good

# With parentheses, there's no ambiguity.
do_something(*some_array)

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end

# good
def test
  return unless something
  work
end

# also good
def test
  work if something
end

# bad
if something
  raise 'exception'
else
  ok
end

# good
raise 'exception' if something
ok

This cop checks for uses of fail and raise.

Example: EnforcedStyle: only_raise (default)

# The `only_raise` style enforces the sole use of `raise`.
# bad
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  # handle it
end

Kernel.fail

# good
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  raise
rescue Exception
  # handle it
end

Kernel.raise

Example: EnforcedStyle: only_fail

# The `only_fail` style enforces the sole use of `fail`.
# bad
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  raise
rescue Exception
  # handle it
end

Kernel.raise

# good
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  # handle it
end

Kernel.fail

Example: EnforcedStyle: semantic

# The `semantic` style enforces the use of `fail` to signal an
# exception, then will use `raise` to trigger an offense after
# it has been rescued.
# bad
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  # Error thrown
rescue Exception
  fail
end

Kernel.fail
Kernel.raise

# good
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  raise 'Preferably with descriptive message'
end

explicit_receiver.fail
explicit_receiver.raise

This cop enforces the use of either #alias or #alias_method depending on configuration. It also flags uses of alias :symbol rather than alias bareword.

Example: EnforcedStyle: prefer_alias (default)

# bad
alias_method :bar, :foo
alias :bar :foo

# good
alias bar foo

Example: EnforcedStyle: preferaliasmethod

# bad
alias :bar :foo
alias bar foo

# good
alias_method :bar, :foo

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true

# Some documentation for Person
class Person
  # Some code
end

# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

This cop enforces the use of either #alias or #alias_method depending on configuration. It also flags uses of alias :symbol rather than alias bareword.

Example: EnforcedStyle: prefer_alias (default)

# bad
alias_method :bar, :foo
alias :bar :foo

# good
alias bar foo

Example: EnforcedStyle: preferaliasmethod

# bad
alias :bar :foo
alias bar foo

# good
alias_method :bar, :foo

This cop checks the indentation of the first element in an array literal where the opening bracket and the first element are on separate lines. The other elements' indentations are handled by the AlignArray cop.

By default, array literals that are arguments in a method call with parentheses, and where the opening square bracket of the array is on the same line as the opening parenthesis of the method call, shall have their first element indented one step (two spaces) more than the position inside the opening parenthesis.

Other array literals shall have their first element indented one step more than the start of the line where the opening square bracket is.

This default style is called 'specialinsideparentheses'. Alternative styles are 'consistent' and 'align_brackets'. Here are examples:

Example: EnforcedStyle: specialinsideparentheses (default)

# The `special_inside_parentheses` style enforces that the first
# element in an array literal where the opening bracket and first
# element are on seprate lines is indented one step (two spaces) more
# than the position inside the opening parenthesis.

#bad
array = [
  :value
]
and_in_a_method_call([
  :no_difference
                     ])

#good
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
                     ])

Example: EnforcedStyle: consistent

# The `consistent` style enforces that the first element in an array
# literal where the opening bracket and the first element are on
# seprate lines is indented the same as an array literal which is not
# defined inside a method call.

#bad
# consistent
array = [
  :value
]
but_in_a_method_call([
                       :its_like_this
])

#good
array = [
  :value
]
and_in_a_method_call([
  :no_difference
])

Example: EnforcedStyle: align_brackets

# The `align_brackets` style enforces that the opening and closing
# brackets are indented to the same position.

#bad
# align_brackets
and_now_for_something = [
                          :completely_different
]

#good
# align_brackets
and_now_for_something = [
                          :completely_different
                        ]

This cop checks whether constant names are written using SCREAMINGSNAKECASE.

To avoid false positives, it ignores cases in which we cannot know for certain the type of value that would be assigned to a constant.

Example:

# bad
InchInCm = 2.54
INCHinCM = 2.54
Inch_In_Cm = 2.54

# good
INCH_IN_CM = 2.54

This cop checks for uses of fail and raise.

Example: EnforcedStyle: only_raise (default)

# The `only_raise` style enforces the sole use of `raise`.
# bad
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  # handle it
end

Kernel.fail

# good
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  raise
rescue Exception
  # handle it
end

Kernel.raise

Example: EnforcedStyle: only_fail

# The `only_fail` style enforces the sole use of `fail`.
# bad
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  raise
rescue Exception
  # handle it
end

Kernel.raise

# good
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  # handle it
end

Kernel.fail

Example: EnforcedStyle: semantic

# The `semantic` style enforces the use of `fail` to signal an
# exception, then will use `raise` to trigger an offense after
# it has been rescued.
# bad
begin
  raise
rescue Exception
  # handle it
end

def watch_out
  # Error thrown
rescue Exception
  fail
end

Kernel.fail
Kernel.raise

# good
begin
  fail
rescue Exception
  # handle it
end

def watch_out
  fail
rescue Exception
  raise 'Preferably with descriptive message'
end

explicit_receiver.fail
explicit_receiver.raise

This cop checks for missing top-level documentation of classes and modules. Classes with no body are exempt from the check and so are namespace modules - modules that have nothing in their bodies except classes, other modules, or constant definitions.

The documentation requirement is annulled if the class or module has a "#:nodoc:" comment next to it. Likewise, "#:nodoc: all" does the same for all its children.

Example:

# bad
class Person
  # ...
end

# good
# Description/Explanation of Person class
class Person
  # ...
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true

# Some documentation for Person
class Person
  # Some code
end

# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

This cop enforces the use of either #alias or #alias_method depending on configuration. It also flags uses of alias :symbol rather than alias bareword.

Example: EnforcedStyle: prefer_alias (default)

# bad
alias_method :bar, :foo
alias :bar :foo

# good
alias bar foo

Example: EnforcedStyle: preferaliasmethod

# bad
alias :bar :foo
alias bar foo

# good
alias_method :bar, :foo