minitest mock expectations

Provides method call assertions for minitest.

Installation

Add this line to your application's Gemfile:

gem "minitest-mock_expectations"

And then execute:

$ bundle

Or install it as:

$ gem install minitest-mock_expectations

Usage

require "minitest/mock_expectations"

Imagine we have model Post:

class Post
  attr_accessor :title, :body
  attr_reader :comments

  def initialize(title: "", body: "", comments: [])
    @title = title
    @body = body
    @comments = comments
  end

  def add_comment(comment)
    @comments << comment

    "Thank you!"
  end
end

and @post variable that refers to an instance of Post:

def setup
  @post = Post.new(
    title: "What is new in Rails 6.0",
    body: "https://gitlab.com/bogdanvlviv/posts/-/issues/15",
    comments: [
      "Wow.",
      "I like this post."
    ]
  )
end

assert_called(object, method_name, message = nil, times: 1, returns: nil)

Asserts that the method will be called on the object in the block

assert_called(@post, :title) do
  @post.title
end

To assert that the method will be called multiple times on the object in the block set :times option:

assert_called(@post, :title, times: 2) do
  @post.title
  @post.title
end

You can stub the return value of the method in the block via :returns option:

assert_called(@post, :title, returns: "What is new in Rails 5.2") do
  assert_equal "What is new in Rails 5.2", @object.title
end

assert_equal "What is new in Rails 6.0", @object.title

refute_called(object, method_name, message = nil, &block)

Asserts that the method will not be called on the object in the block

refute_called(@post, :title) do
  @post.body
end

assert_not_called

Alias for refute_called.

assert_called_with(object, method_name, arguments, returns: nil)

Asserts that the method will be called with the arguments on the object in the block

assert_called_with(@post, :add_comment, ["Thanks for sharing this."]) do
  @post.add_comment("Thanks for sharing this.")
end

You can stub the return value of the method in the block via :returns option:

assert_called_with(@post, :add_comment, ["Thanks for sharing this."], returns: "Thanks!") do
  assert_equal "Thanks!", @post.add_comment("Thanks for sharing this.")
end

assert_equal "Thank you!", @post.add_comment("Thanks for sharing this.")

You can also assert that the method will be called with different arguments on the object in the block:

assert_called_with(@post, :add_comment, [["Thanks for sharing this."], ["Thanks!"]]) do
  @post.add_comment("Thanks for sharing this.")
  @post.add_comment("Thanks!")
end

assert_called_with(@post, :add_comment, [[["Thanks for sharing this."]]]) do
  @post.add_comment(["Thanks for sharing this."])
end

assert_called_with(@post, :add_comment, [[["Thanks for sharing this.", "Thanks!"]]]) do
  @post.add_comment(["Thanks for sharing this.", "Thanks!"])
end

assert_called_with(@post, :add_comment, [[["Thanks for sharing this."], ["Thanks!"]]]) do
  @post.add_comment(["Thanks for sharing this."], ["Thanks!"])
end

assert_called_with(@post, :add_comment, [["Thanks for sharing this."], {body: "Thanks!"}]) do
  @post.add_comment(["Thanks for sharing this."], {body: "Thanks!"})
end

assert_called_with(@post, :add_comment, [[["Thanks for sharing this."]], [{body: "Thanks!"}]]) do
  @post.add_comment(["Thanks for sharing this."])
  @post.add_comment({body: "Thanks!"})
end

assert_called_with(@post, :add_comment, [[["Thanks for sharing this."]], [["Thanks!"]]]) do
  @post.add_comment(["Thanks for sharing this."])
  @post.add_comment(["Thanks!"])
end

assert_called_on_instance_of(klass, method_name, message = nil, times: 1, returns: nil)

Asserts that the method will be called on an instance of the klass in the block

assert_called_on_instance_of(Post, :title) do
  @post.title
end

To assert that the method will be called multiple times on an instance of the klass in the block set :times option:

assert_called_on_instance_of(Post, :title, times: 2) do
  @post.title
  @post.title
end

You can stub the return value of the method in the block via :returns option:

assert_called_on_instance_of(Post, :title, returns: "What is new in Rails 5.2") do
  assert_equal "What is new in Rails 5.2", @post.title
end

assert_equal "What is new in Rails 6.0", @post.title

Use nesting of the blocks to assert that the several methods will be called on an instance of the klass in the block:

assert_called_on_instance_of(Post, :title, times: 3) do
  assert_called_on_instance_of(Post, :body, times: 2) do
    @post.title
    @post.body
    @post.title
    @post.body
    @post.title
  end
end

refute_called_on_instance_of(klass, method_name, message = nil, &block)

Asserts that the method will not be called on an instance of the klass in the block

refute_called_on_instance_of(Post, :title) do
  @post.body
end

Use nesting of the blocks to assert that the several methods will not be called on an instance of the klass in the block:

refute_called_on_instance_of(Post, :title) do
  refute_called_on_instance_of(Post, :body) do
    @post.add_comment("Thanks for sharing this.")
  end
end

assert_not_called_on_instance_of

Alias for refute_called_on_instance_of.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/bogdanvlviv/minitest-mock_expectations. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.