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Contents
Feature: Test Doubles
_Test double_ is a generic term for any object that stands in for a real object during a test
(think "stunt double"). You create one using the `double` method. Doubles are "strict" by
default -- any message you have not allowed or expected will trigger an error -- but you can
[switch a double to being "loose"](./null-object-doubles). When creating a double, you can allow messages (and set
their return values) by passing a hash.
Once you have a test double, you can [allow](./allowing-messages) or [expect](./expecting-messages) messages on it.
We recommend you use [verifying doubles](../verifying-doubles) whenever possible.
Scenario: Doubles are strict by default
Given a file named "double_spec.rb" with:
"""ruby
RSpec.describe "A test double" do
it "raises errors when messages not allowed or expected are received" do
dbl = double("Some Collaborator")
dbl.foo
end
end
"""
When I run `rspec double_spec.rb`
Then it should fail with:
"""
#<Double "Some Collaborator"> received unexpected message :foo with (no args)
"""
Scenario: A hash can be used to define allowed messages and return values
Given a file named "double_spec.rb" with:
"""ruby
RSpec.describe "A test double" do
it "returns canned responses from the methods named in the provided hash" do
dbl = double("Some Collaborator", :foo => 3, :bar => 4)
expect(dbl.foo).to eq(3)
expect(dbl.bar).to eq(4)
end
end
"""
When I run `rspec double_spec.rb`
Then the examples should all pass
Version data entries
5 entries across 5 versions & 1 rubygems