ActiveMocker

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.rb and the defined methods on a model then generates a ruby file that can be included within a test. The mock file can be run by themselves and come with a partial implementation of ActiveRecord. Attributes and associations can be used just the same as in ActiveRecord. Methods will have the correct arguments but raise an NotImplementedError when called. Mocks are regenerated when the schema is modified so your mocks will not go stale; preventing the case where your units tests pass but production code fails.

Examples from a real apps

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Documentation
Contact
Installation
Setup
- Generate
Dependencies
Usage
Mocking Methods
Managing Mocks
ActiveRecord supported methods
Known Limitations
Inspiration
Contributing

Documentation

rdoc

Contact

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Installation

Add this line to your application's Gemfile:

group :development, :test do
  gem 'active_mocker'
end

It needs to be in development as well as test because development is where mocks will be generated. 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

See example_rails_app for complete setup.

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

Using With Rspec, --tag active_mocker:true

require 'rspec'
require 'active_mocker/rspec_helper'
require 'spec/mocks/person_mock'
require 'spec/mocks/account_mock'

describe 'Example', active_mocker:true do

  before do
    Person.create # stubbed for PersonMock.create
  end

end

Assigning the tag active_mocker:true will stub any ActiveRecord model Constants for Mock classes in an it or a before/after(:each). This removes any need for dependency injection. Write tests and code like you would normally.
To stub any Constants in before(:all), after(:all) use mock_class('ClassName').
Mock state will be cleaned up for you in an after(:all). To clean state your self use ActiveMocker::LoadedMocks.delete_all.

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

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

person.first_name
  => "Dustin"

When schema.rb changes, the mock fails

(After rake db:migrate is called the mocks will be regenerated.)

#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.new(first_name: "Dustin", last_name: "Zeisler")
  =>#<UnknownAttributeError unknown attribute: first_name >

Mocking Methods

Rspec 3 Mocks - verify double

Verifying doubles are a stricter alternative to normal doubles that provide guarantees about what is being verified. When using verifying doubles, RSpec will check that the methods being stubbed are actually present on the underlying object if it is available. rspec-mocks/docs/verifying-doubles

RSpec.configure do |config|
  config.mock_framework = :rspec
  config.mock_with :rspec do |mocks|
    mocks.verify_doubled_constant_names = true
    mocks.verify_partial_doubles = true
  end
end

Person.bar('baz')
  => NotImplementedError: ::bar is not Implemented for Class :PersonMock. To continue stub the method.

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

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

# Rspec 3 mock class method
allow_any_instance_of(Person).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.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

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

Constants and Modules

Any locally defined modules will not be included or extended.

class Person < ActiveRecord::Base
  CONSTANT_VALUE = 13
end

PersonMock::CONSTANT_VALUE
  => 13

Scoped Methods

Any chained scoped methods will be available when the mock file that defines it is required. When called it raises a NotImplementedError, stub the method with a value to continue.

Managing Mocks

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

ActiveMocker::LoadedMocks.delete_all

ActiveRecord supported methods

See Documentation for a complete list of methods and usage.

Class Methods - docs

new
create/create!
column_names/attribute_names
delete_all/destroy_all
table_name

Query Methods - docs

all
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
update(id, attributes)
count
uniq
first/last
average(:field_name)
minimum(:field_name)
maximum(:field_name)
sum(:field_name)
order(:field_name)
reverse_order
limit

Relation Methods - docs

concat
include
push
clear
take
empty?
replace
any?
many?

instance methods - docs

attributes
update
save/save!
write_attribute/read_attribute - (protected, can be used within modules)
delete
new_record?
persisted?
reload
attribute_names
attribute_present?
has_attribute?

has_one/belongs_to/has_many

build_< association >
create_< association >
create_< association >!
< 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 is supported.
Scale and Precision are not supported.

Known Limitations

Model names and table names must follow the default ActiveRecord naming pattern.
When an association is set in one object it may not always be reflective in other objects, especially when it is a non standard/custom association. See test_rails_4_app/spec/active_record_compatible_api.rb for a complete list of supported associations.
Validation/Callbacks are not supported.
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!

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