ece517-p3/expertiza

This warning comes up if a model does not limit what attributes can be set through mass assignment.

In particular, this check looks for attr_accessible inside model definitions. If it is not found, this warning will be issued.

Brakeman also warns on use of attr_protected - especially since it was found to be vulnerable to bypass. Warnings for mass assignment on models using attr_protected will be reported, but at a lower confidence level.

Note that disabling mass assignment globally will suppress these warnings.

This cop checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric

This cop looks for has(one|many) and belongsto associations where ActiveRecord can't automatically determine the inverse association because of a scope or the options used. This can result in unnecessary queries in some circumstances. :inverse_of must be manually specified for associations to work in both ways, or set to false to opt-out.

Example:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Blog < ApplicationRecord
  has_many :posts, -> { order(published_at: :desc) }
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  has_many(:posts,
    -> { order(published_at: :desc) },
    inverse_of: :blog
  )
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  with_options inverse_of: :blog do
    has_many :posts, -> { order(published_at: :desc) }
  end
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable
end

# good
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

Example:

# bad
# However, RuboCop can not detect this pattern...
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician
  belongs_to :patient
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

# good
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician, inverse_of: :appointments
  belongs_to :patient, inverse_of: :appointments
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

@see http://guides.rubyonrails.org/association_basics.html#bi-directional-associations @see http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#module-ActiveRecord::Associations::ClassMethods-label-Setting+Inverses

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end

This cop looks for has_many or has_one associations that don't specify a :dependent option. It doesn't register an offense if :through option was specified.

Example:

# bad
class User < ActiveRecord::Base
  has_many :comments
  has_one :avatar
end

# good
class User < ActiveRecord::Base
  has_many :comments, dependent: :restrict_with_exception
  has_one :avatar, dependent: :destroy
  has_many :patients, through: :appointments
end

This cop looks for has(one|many) and belongsto associations where ActiveRecord can't automatically determine the inverse association because of a scope or the options used. This can result in unnecessary queries in some circumstances. :inverse_of must be manually specified for associations to work in both ways, or set to false to opt-out.

Example:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Blog < ApplicationRecord
  has_many :posts, -> { order(published_at: :desc) }
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  has_many(:posts,
    -> { order(published_at: :desc) },
    inverse_of: :blog
  )
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  with_options inverse_of: :blog do
    has_many :posts, -> { order(published_at: :desc) }
  end
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable
end

# good
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

Example:

# bad
# However, RuboCop can not detect this pattern...
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician
  belongs_to :patient
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

# good
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician, inverse_of: :appointments
  belongs_to :patient, inverse_of: :appointments
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

@see http://guides.rubyonrails.org/association_basics.html#bi-directional-associations @see http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#module-ActiveRecord::Associations::ClassMethods-label-Setting+Inverses

This cop looks for has(one|many) and belongsto associations where ActiveRecord can't automatically determine the inverse association because of a scope or the options used. This can result in unnecessary queries in some circumstances. :inverse_of must be manually specified for associations to work in both ways, or set to false to opt-out.

Example:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Blog < ApplicationRecord
  has_many :posts, -> { order(published_at: :desc) }
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  has_many(:posts,
    -> { order(published_at: :desc) },
    inverse_of: :blog
  )
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  with_options inverse_of: :blog do
    has_many :posts, -> { order(published_at: :desc) }
  end
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable
end

# good
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

Example:

# bad
# However, RuboCop can not detect this pattern...
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician
  belongs_to :patient
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

# good
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician, inverse_of: :appointments
  belongs_to :patient, inverse_of: :appointments
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

@see http://guides.rubyonrails.org/association_basics.html#bi-directional-associations @see http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#module-ActiveRecord::Associations::ClassMethods-label-Setting+Inverses

Duplicated Code

Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:

Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).

Tuning

This issue has a mass of 34.

We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.

If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

See codeclimate-duplication's documentation for more information about tuning the mass threshold in your .codeclimate.yml.

Refactorings

• Extract Method
• Extract Class
• Form Template Method
• Introduce Null Object
• Pull Up Method
• Pull Up Field
• Substitute Algorithm

Further Reading

• Don't Repeat Yourself on the C2 Wiki
• Duplicated Code on SourceMaking
• Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76

This cop makes sure that predicates are named properly.

Example:

# bad
def is_even?(value)
end

# good
def even?(value)
end

# bad
def has_value?
end

# good
def value?
end