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Feature: let and let!
Use `let` to define a memoized helper method. The value will be cached across
multiple calls in the same example but not across examples.
Note that `let` is lazy-evaluated: it is not evaluated until the first time
the method it defines is invoked. You can use `let!` to force the method's
invocation before each example.
By default, `let` is threadsafe, but you can configure it not to be
by disabling `config.threadsafe`, which makes `let` perform a bit faster.
Scenario: Use `let` to define memoized helper method
Given a file named "let_spec.rb" with:
"""ruby
$count = 0
RSpec.describe "let" do
let(:count) { $count += 1 }
it "memoizes the value" do
expect(count).to eq(1)
expect(count).to eq(1)
end
it "is not cached across examples" do
expect(count).to eq(2)
end
end
"""
When I run `rspec let_spec.rb`
Then the examples should all pass
Scenario: Use `let!` to define a memoized helper method that is called in a `before` hook
Given a file named "let_bang_spec.rb" with:
"""ruby
$count = 0
RSpec.describe "let!" do
invocation_order = []
let!(:count) do
invocation_order << :let!
$count += 1
end
it "calls the helper method in a before hook" do
invocation_order << :example
expect(invocation_order).to eq([:let!, :example])
expect(count).to eq(1)
end
end
"""
When I run `rspec let_bang_spec.rb`
Then the examples should all pass