ActiveMocker

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ActiveMocker creates mocks classes from ActiveRecord models. Allowing your test suite to run very fast by not loading Rails or hooking to a database. It parses the schema definition and the defined methods on a model then saves a ruby file that can be included within a test. Mocks are regenerated when the schema is modified so your mocks will not go stale. This prevents the case where your units tests pass but production code is failing.

Example from a real app

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Contact

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Installation

Add this line to your application's Gemfile:

gem 'active_mocker'

And then execute:

$ bundle

Or install it yourself as:

$ gem install active_mocker

Dependencies

  • Tested with Rails 4.1 may work with older versions but not supported.
  • Requires Ruby MRI =< 2.1.

Setup

Overwrite defaults configuration

ActiveMocker::Generate.configure do |config|
  config.schema_file = File.join(Rails.root, 'db/schema.rb')
  config.model_dir   = File.join(Rails.root, 'app/models')
  config.mock_dir    = File.join(Rails.root, 'spec/mocks')
  config.logger      = Rails.logger
end

Generate Mocks

Running this rake task builds/rebuilds the mocks. It will be ran automatically after every schema modification. If the model changes this rake task needs to be called manually. You could add a file watcher for when your models change and have it run the rake task.

rake active_mocker::build

Usage

#db/schema.rb

ActiveRecord::Schema.define(version: 20140327205359) do

  create_table "people", force: true do |t|
    t.integer  "account_id"
    t.string   "first_name",        limit: 128
    t.string   "last_name",         limit: 128
    t.string   "address",           limit: 200
    t.string   "city",              limit: 100
  end

end

#app/models/person.rb

class Person < ActiveRecord::Base
  belongs_to :account

  def bar(name, type=nil)
    puts name
  end

  def self.bar
  end

end

#person_spec.rb

require 'spec/mocks/person_mock.rb'
require 'spec/mocks/account_mock.rb'

PersonMock.column_names
    => ["id", "account_id", "first_name", "last_name", "address", "city"]

person_mock = PersonMock.new( first_name:  "Dustin", 
                              last_name:   "Zeisler", 
                              account:      AccountMock.new )
    => "#<PersonMock id: nil, account_id: nil, first_name: "Dustin", last_name: "Zeisler, address: nil, city: nil>"

 person_mock.first_name
    => "Dustin"

When schema.rb changes, the mock fails

(Requires a regeneration of the mocks files.)

#db/schema.rb

 ActiveRecord::Schema.define(version: 20140327205359) do

   create_table "people", force: true do |t|
     t.integer  "account_id"
     t.string   "f_name",        limit: 128
     t.string   "l_name",        limit: 128
     t.string   "address",       limit: 200
     t.string   "city",          limit: 100
   end

 end

#person_spec.rb

 PersonMock.new(first_name: "Dustin", last_name: "Zeisler")
         =>#<RuntimeError Rejected params: {"first_name"=>"Dustin", "last_name"=>"Zeisler"} for PersonMock>

Mocking Methods

Class Methods

 PersonMock.bar('baz')
    => RuntimeError: ::bar is not Implemented for Class: PersonMock

 # Rspec 3 Mocks
 allow(PersonMock).to receive(:bar) do  |name, type=nil|
    "Now implemented with #{name} and #{type}"
 end

Instance Methods

  PersonMock.new.bar('foo', 'type')
    => "Now implemented with foo and type"

  # Rspec 3 Mocks
  allow_any_instance(PersonMock).to receive(:bar) do
     "Now implemented"
  end

When the model changes, the mock fails

(Requires a regeneration of the mocks files.)

#app/models/person.rb

class Person < ActiveRecord::Base
  belongs_to :account

  def bar(name)
    puts name
  end

end

#person_spec.rb

person_mock.new.bar('foo', 'type')
  => ArgumentError: wrong number of arguments (2 for 1)

#app/models/person.rb

class Person < ActiveRecord::Base
  belongs_to :account

  def foo(name, type=nil)
    puts name
  end

end

 #person_spec.rb

# Rspec 3 Mocks
allow(person_mock).to receive(:bar) do  |name, type=nil|
  "Now implemented with #{name} and #{type}"
end
  => NoMethodError: undefined method `bar' for class `PersonMock'

Managing Mocks

Rspec Tag - active_mocker:true

describe 'Example', active_mocker:true do

end

Assigning this tag will stub any ActiveRecord model Constants for Mock classes in any it's or before(:each). To stub any Constants in before(:all), after(:all) use mock_class('ClassName').

Deletes All Records and Clears Mocked Methods

PersonMock.clear_mock

Clears all Loaded Mocks - (Use in after(:all) to keep state from leaking to other tests.)

ActiveMocker::LoadedMocks.clear_all

Deletes All Records for Loaded Mocks - (Useful in after(:each) to clean up state between examples)

ActiveMocker::LoadedMocks.delete_all

List All Loaded Mocks

ActiveMocker::LoadedMocks.all
        => { 'PersonMock' => PersonMock }

Map The Mock Class to it's Model

ActiveMocker::LoadedMocks.class_name_to_mock
    => { 'Person' => PersonMock }

Constants and included and extended Modules are Available.

#app/models/person.rb

class User < ActiveRecord::Base
   CONSTANT_VALUE = 13
end

#user_spec.rb

require 'spec/mocks/user_mock.rb'

UserMock::CONSTANT_VALUE
    => 13

Mocked Class

UserMock.mocked_class
    => 'User'

ActiveRecord supported methods

class methods

  • new
  • create/create!
  • column_names/attribute_names
  • find
  • find_by/find_by!
  • find_or_create_by
  • find_or_initialize_by
  • where(conditions_hash)
  • where(key: array_of_values)
  • where.not(conditions_hash)
  • delete_all/destroy_all
  • delete_all(conditions_hash)
  • destroy(id)/delete(id)
  • update_all
  • all
  • count
  • first/last
  • limit

instance methods

  • attributes
  • update
  • save/save!
  • write_attribute/read_attribute - (protected, can be used within modules)
  • delete

has_one/belongs_to

  • build_< association >
  • create_< association >
  • create_< association >!

has_many associations/Collections

  • empty?
  • length/size/count
  • uniq
  • replace
  • first/last
  • concat
  • include
  • push
  • clear
  • take
  • average(:field_name)
  • minimum(:field_name)
  • maximum(:field_name)
  • sum(:field_name)
  • find
  • find_by/find_by!
  • where(conditions_hash)
  • where(key: array_of_values)
  • where.not(conditions_hash)
  • update_all
  • delete_all
  • order(:field_name)
  • reverse_order
  • limit
  • < association >.create
  • < association >.build

Schema/Migration Option Support

  • All schema types are supported and coerced by Virtus. If coercion fails the passed value will be retained.
  • Default value
  • Scale and Precision not supported.

Known Limitations

  • Model names and table names must follow the default ActiveRecord naming pattern.
  • Whatever associations are setup in one mock object will not reflected in any other objects.
  • Validation are not present in mocks.
  • Sql queries, joins, etc will never be supported.

Inspiration

Thanks to Jeff Olfert for being my original inspiration for this project.

Contributing

Your contribution are welcome!

  1. Fork it ( http://github.com/zeisler/active_mocker/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request