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Feature: Anonymous test doubles
Anonymous test doubles can be useful as a stepping stone towards actual fakes and when migrating from another testing library.
In contrast with other testing libraries, Bogus makes its fakes respond to all methods by default. This way you can spy on methods without stubbing them first.
It is not advisable to use those for anything else than an intermediate step. Fakes that mimic an actual class have many more benefits.
The syntax for defining fakes is:
fake(method_1: return_value, method_2: proc{return_value2})
If you pass a proc as a return value to a fake, the proc will be called to obtain the value. This can be used for instance to raise errors in stubbed methods.
If you want to actually return a proc from a method, you need to use a slightly longer syntax:
factory = fake()
stub(factory).make_validator{ proc{ false } }
Background:
Given a file named "student.rb" with:
"""ruby
class Student
attr_reader :library_card
def initialize(name)
@name = name
end
def sign_up(library)
@library_card = library.register_junior(@name)
end
end
"""
Scenario: Stubbing any method with any parameters
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake }
let(:jake) { Student.new("Jake") }
it "allows stubbing any method with any parameters" do
stub(library).register_junior(any_args) { "the card" }
jake.sign_up(library)
expect(jake.library_card).to eq("the card")
end
end
"""
Scenario: Stubbing methods in initializer
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake(register_junior: "the card") }
let(:jake) { Student.new("Jake") }
it "allows stubbing any method with any parameters" do
jake.sign_up(library)
expect(jake.library_card).to eq("the card")
end
end
"""
Scenario: Stubbing methods inline by passing a block
Then the following test should pass:
"""ruby
library = fake(register_junior: proc{ raise "library full!" })
expect {
library.register_junior("Jake")
}.to raise_error("library full!")
"""
Scenario: Mocking any method with any parameters
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake }
let(:jake) { Student.new("Jake") }
it "allows mocking any method with any parameters" do
mock(library).register_junior("Jake") { "the card" }
jake.sign_up(library)
expect(jake.library_card).to eq("the card")
end
end
"""
Scenario: Mocking any method with any parameters
Then spec file with following content should fail:
"""ruby
require_relative 'student'
describe Student do
it "allows stubbing any method with any parameters" do
library = fake
mock(library).register_junior { "the card" }
end
end
"""
Scenario: Stubbing methods in initializer
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake(register_junior: "the card") }
let(:jake) { Student.new("Jake") }
it "allows stubbing any method with any parameters" do
jake.sign_up(library)
expect(jake.library_card).to eq("the card")
end
end
"""
Scenario: Spying on method calls
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake }
let(:jake) { Student.new("Jake") }
it "allows spying on any method" do
jake.sign_up(library)
expect(library).to have_received.register_junior("Jake")
end
end
"""
Scenario: Invoking arbitrary methods
Then spec file with following content should pass:
"""ruby
require_relative 'student'
describe Student do
let(:library) { fake }
it "allows calling any method with any parameters" do
expect {
library.foo
library.bar("hello")
library.baz(1, 2, 3, 4, 5)
}.not_to raise_error
end
end
"""
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