ManageIQ/manageiq

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 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 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 the presence of precise comparison of floating point numbers.

Floating point values are inherently inaccurate, and comparing them for exact equality is almost never the desired semantics. Comparison via the ==/!= operators checks floating-point value representation to be exactly the same, which is very unlikely if you perform any arithmetic operations involving precision loss.

Example:

# bad
x == 0.1
x != 0.1

# good - using BigDecimal
x.to_d == 0.1.to_d

# good
(x - 0.1).abs < Float::EPSILON

# good
tolerance = 0.0001
(x - 0.1).abs < tolerance

# Or some other epsilon based type of comparison:
# https://www.embeddeduse.com/2019/08/26/qt-compare-two-floats/

Checks for unintended or-assignment to a constant.

Constants should always be assigned in the same location. And its value should always be the same. If constants are assigned in multiple locations, the result may vary depending on the order of require.

Safety:

This cop is unsafe because code that is already conditionally assigning a constant may have its behavior changed by autocorrection.

Example:

# bad
CONST ||= 1

# good
CONST = 1

Checks for the use of YAML class methods which have potential security issues leading to remote code execution when loading from an untrusted source.

NOTE: Ruby 3.1+ (Psych 4) uses Psych.load as Psych.safe_load by default.

Safety:

The behavior of the code might change depending on what was in the YAML payload, since YAML.safe_load is more restrictive.

Example:

# bad
YAML.load("--- !ruby/object:Foo {}") # Psych 3 is unsafe by default

# good
YAML.safe_load("--- !ruby/object:Foo {}", [Foo])                    # Ruby 2.5  (Psych 3)
YAML.safe_load("--- !ruby/object:Foo {}", permitted_classes: [Foo]) # Ruby 3.0- (Psych 3)
YAML.load("--- !ruby/object:Foo {}", permitted_classes: [Foo])      # Ruby 3.1+ (Psych 4)
YAML.dump(foo)

Enforce that development dependencies for a gem are specified in Gemfile, rather than in the gemspec using add_development_dependency. Alternatively, using EnforcedStyle: gemspec, enforce that all dependencies are specified in gemspec, rather than in Gemfile.

Example: EnforcedStyle: Gemfile (default)

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gems.rb

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.
#
# Identical to `EnforcedStyle: Gemfile`, but with a different error message.
# Rely on Bundler/GemFilename to enforce the use of `Gemfile` vs `gems.rb`.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gemspec

# Specify all dependencies in your gemspec.

# bad
# Gemfile
gem "foo"

# good
# example.gemspec
s.add_development_dependency "foo"

# good (with AllowedGems: ["bar"])
# Gemfile
gem "bar"

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 unintended or-assignment to a constant.

Constants should always be assigned in the same location. And its value should always be the same. If constants are assigned in multiple locations, the result may vary depending on the order of require.

Safety:

This cop is unsafe because code that is already conditionally assigning a constant may have its behavior changed by autocorrection.

Example:

# bad
CONST ||= 1

# good
CONST = 1

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 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

Enforce that development dependencies for a gem are specified in Gemfile, rather than in the gemspec using add_development_dependency. Alternatively, using EnforcedStyle: gemspec, enforce that all dependencies are specified in gemspec, rather than in Gemfile.

Example: EnforcedStyle: Gemfile (default)

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gems.rb

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.
#
# Identical to `EnforcedStyle: Gemfile`, but with a different error message.
# Rely on Bundler/GemFilename to enforce the use of `Gemfile` vs `gems.rb`.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gemspec

# Specify all dependencies in your gemspec.

# bad
# Gemfile
gem "foo"

# good
# example.gemspec
s.add_development_dependency "foo"

# good (with AllowedGems: ["bar"])
# Gemfile
gem "bar"

Enforce that development dependencies for a gem are specified in Gemfile, rather than in the gemspec using add_development_dependency. Alternatively, using EnforcedStyle: gemspec, enforce that all dependencies are specified in gemspec, rather than in Gemfile.

Example: EnforcedStyle: Gemfile (default)

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gems.rb

# Specify runtime dependencies in your gemspec,
# but all other dependencies in your Gemfile.
#
# Identical to `EnforcedStyle: Gemfile`, but with a different error message.
# Rely on Bundler/GemFilename to enforce the use of `Gemfile` vs `gems.rb`.

# bad
# example.gemspec
s.add_development_dependency "foo"

# good
# Gemfile
gem "foo"

# good
# gems.rb
gem "foo"

# good (with AllowedGems: ["bar"])
# example.gemspec
s.add_development_dependency "bar"

Example: EnforcedStyle: gemspec

# Specify all dependencies in your gemspec.

# bad
# Gemfile
gem "foo"

# good
# example.gemspec
s.add_development_dependency "foo"

# good (with AllowedGems: ["bar"])
# Gemfile
gem "bar"

Sort globbed results by default in Ruby 3.0. This cop checks for redundant sort method to Dir.glob and Dir[].

Safety:

This cop is unsafe, in case of having a file and a directory with identical names, since directory will be loaded before the file, which will break exe/files.rb that rely on exe.rb file.

Example:

# bad
Dir.glob('./lib/**/*.rb').sort.each do |file|
end

Dir['./lib/**/*.rb'].sort.each do |file|
end

# good
Dir.glob('./lib/**/*.rb').each do |file|
end

Dir['./lib/**/*.rb'].each do |file|
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