ifmeorg/ifme

Checks for places where string concatenation can be replaced with string interpolation.

The cop can autocorrect simple cases but will skip autocorrecting more complex cases where the resulting code would be harder to read. In those cases, it might be useful to extract statements to local variables or methods which you can then interpolate in a string.

NOTE: When concatenation between two strings is broken over multiple lines, this cop does not register an offense; instead, Style/LineEndConcatenation will pick up the offense if enabled.

Two modes are supported: 1. aggressive style checks and corrects all occurrences of + where either the left or right side of + is a string literal. 2. conservative style on the other hand, checks and corrects only if left side (receiver of + method call) is a string literal. This is useful when the receiver is some expression that returns string like Pathname instead of a string literal.

Safety:

This cop is unsafe in aggressive mode, as it cannot be guaranteed that the receiver is actually a string, which can result in a false positive.

Example: Mode: aggressive (default)

# bad
email_with_name = user.name + ' <' + user.email + '>'
Pathname.new('/') + 'test'
 
# good
email_with_name = "#{user.name} <#{user.email}>"
email_with_name = format('%s <%s>', user.name, user.email)
"#{Pathname.new('/')}test"
 
# accepted, line-end concatenation
name = 'First' +
  'Last'

Example: Mode: conservative

# bad
'Hello' + user.name
 
# good
"Hello #{user.name}"
user.name + '!!'
Pathname.new('/') + 'test'

Checks for places where string concatenation can be replaced with string interpolation.

The cop can autocorrect simple cases but will skip autocorrecting more complex cases where the resulting code would be harder to read. In those cases, it might be useful to extract statements to local variables or methods which you can then interpolate in a string.

NOTE: When concatenation between two strings is broken over multiple lines, this cop does not register an offense; instead, Style/LineEndConcatenation will pick up the offense if enabled.

Two modes are supported: 1. aggressive style checks and corrects all occurrences of + where either the left or right side of + is a string literal. 2. conservative style on the other hand, checks and corrects only if left side (receiver of + method call) is a string literal. This is useful when the receiver is some expression that returns string like Pathname instead of a string literal.

Safety:

This cop is unsafe in aggressive mode, as it cannot be guaranteed that the receiver is actually a string, which can result in a false positive.

Example: Mode: aggressive (default)

# bad
email_with_name = user.name + ' <' + user.email + '>'
Pathname.new('/') + 'test'
 
# good
email_with_name = "#{user.name} <#{user.email}>"
email_with_name = format('%s <%s>', user.name, user.email)
"#{Pathname.new('/')}test"
 
# accepted, line-end concatenation
name = 'First' +
  'Last'

Example: Mode: conservative

# bad
'Hello' + user.name
 
# good
"Hello #{user.name}"
user.name + '!!'
Pathname.new('/') + 'test'

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

For more information visit Source: http://eslint.org/docs/rules/

Checks for places where keyword arguments can be used instead of boolean arguments when defining methods. respond_to_missing? method is allowed by default. These are customizable with AllowedMethods option.

Safety:

This cop is unsafe because changing a method signature will implicitly change behavior.

Example:

# bad
def some_method(bar = false)
  puts bar
end
 
# bad - common hack before keyword args were introduced
def some_method(options = {})
  bar = options.fetch(:bar, false)
  puts bar
end
 
# good
def some_method(bar: false)
  puts bar
end

Example: AllowedMethods: ['some_method']

# good
def some_method(bar = false)
  puts bar
end

Checks for places where string concatenation can be replaced with string interpolation.

The cop can autocorrect simple cases but will skip autocorrecting more complex cases where the resulting code would be harder to read. In those cases, it might be useful to extract statements to local variables or methods which you can then interpolate in a string.

NOTE: When concatenation between two strings is broken over multiple lines, this cop does not register an offense; instead, Style/LineEndConcatenation will pick up the offense if enabled.

Two modes are supported: 1. aggressive style checks and corrects all occurrences of + where either the left or right side of + is a string literal. 2. conservative style on the other hand, checks and corrects only if left side (receiver of + method call) is a string literal. This is useful when the receiver is some expression that returns string like Pathname instead of a string literal.

Safety:

This cop is unsafe in aggressive mode, as it cannot be guaranteed that the receiver is actually a string, which can result in a false positive.

Example: Mode: aggressive (default)

# bad
email_with_name = user.name + ' <' + user.email + '>'
Pathname.new('/') + 'test'
 
# good
email_with_name = "#{user.name} <#{user.email}>"
email_with_name = format('%s <%s>', user.name, user.email)
"#{Pathname.new('/')}test"
 
# accepted, line-end concatenation
name = 'First' +
  'Last'

Example: Mode: conservative

# bad
'Hello' + user.name
 
# good
"Hello #{user.name}"
user.name + '!!'
Pathname.new('/') + 'test'

Checks for places where keyword arguments can be used instead of boolean arguments when defining methods. respond_to_missing? method is allowed by default. These are customizable with AllowedMethods option.

Safety:

This cop is unsafe because changing a method signature will implicitly change behavior.

Example:

# bad
def some_method(bar = false)
  puts bar
end
 
# bad - common hack before keyword args were introduced
def some_method(options = {})
  bar = options.fetch(:bar, false)
  puts bar
end
 
# good
def some_method(bar: false)
  puts bar
end

Example: AllowedMethods: ['some_method']

# good
def some_method(bar = false)
  puts bar
end

Identifies places where if-elsif constructions can be replaced with case-when.

Safety:

This cop is unsafe. case statements use === for equality, so if the original conditional used a different equality operator, the behavior may be different.

Example: MinBranchesCount: 3 (default)

# bad
if status == :active
  perform_action
elsif status == :inactive || status == :hibernating
  check_timeout
elsif status == :invalid
  report_invalid
else
  final_action
end
 
# good
case status
when :active
  perform_action
when :inactive, :hibernating
  check_timeout
when :invalid
  report_invalid
else
  final_action
end

Example: MinBranchesCount: 4

# good
if status == :active
  perform_action
elsif status == :inactive || status == :hibernating
  check_timeout
elsif status == :invalid
  report_invalid
else
  final_action
end

Checks for non-atomic file operation. And then replace it with a nearly equivalent and atomic method.

These can cause problems that are difficult to reproduce, especially in cases of frequent file operations in parallel, such as test runs with parallel_rspec.

For examples: creating a directory if there is none, has the following problems

An exception occurs when the directory didn't exist at the time of exist?, but someone else created it before mkdir was executed.

Subsequent processes are executed without the directory that should be there when the directory existed at the time of exist?, but someone else deleted it shortly afterwards.

Safety:

This cop is unsafe, because autocorrection change to atomic processing. The atomic processing of the replacement destination is not guaranteed to be strictly equivalent to that before the replacement.

Example:

# bad - race condition with another process may result in an error in `mkdir`
unless Dir.exist?(path)
  FileUtils.mkdir(path)
end
 
# good - atomic and idempotent creation
FileUtils.mkdir_p(path)
 
# bad - race condition with another process may result in an error in `remove`
if File.exist?(path)
  FileUtils.remove(path)
end
 
# good - atomic and idempotent removal
FileUtils.rm_f(path)

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0
 
# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?
 
# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0
 
# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?
 
# bad
foo.negative?
bar.baz.positive?