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## Mutating Constants
### Stubbing
Support is provided for stubbing constants. Like with method stubs, the
stubbed constants will be restored to their original state when an
example completes.
``` ruby
stub_const("Foo", fake_foo)
Foo # => fake_foo
```
Stubbed constant names must be fully qualified; the current module
nesting is not considered.
``` ruby
module MyGem
class SomeClass; end
end
module MyGem
describe "Something" do
let(:fake_class) { Class.new }
it "accidentally stubs the wrong constant" do
# this stubs ::SomeClass (in the top-level namespace),
# not MyGem::SomeClass like you probably mean.
stub_const("SomeClass", fake_class)
end
it "stubs the right constant" do
stub_const("MyGem::SomeClass", fake_class)
end
end
end
```
When you stub a constant that is a module or a class, nested
constants on the original module or class are not transferred
by default, but you can use the `:transfer_nested_constants`
option to tell rspec-mocks to transfer them:
``` ruby
class CardDeck
SUITS = [:Spades, :Diamonds, :Clubs, :Hearts]
NUM_CARDS = 52
end
fake_class = Class.new
stub_const("CardDeck", fake_class)
CardDeck # => fake_class
CardDeck::SUITS # => raises uninitialized constant error
CardDeck::NUM_CARDS # => raises uninitialized constant error
stub_const("CardDeck", fake_class, :transfer_nested_constants => true)
CardDeck::SUITS # => [:Spades, :Diamonds, :Clubs, :Hearts]
CardDeck::NUM_CARDS # => 52
stub_const("CardDeck", fake_class, :transfer_nested_constants => [:SUITS])
CardDeck::SUITS # => [:Spades, :Diamonds, :Clubs, :Hearts]
CardDeck::NUM_CARDS # => raises uninitialized constant error
```
### Hiding
Support is also provided for hiding constants. Hiding a constant temporarily
removes it; it is restored to its original value after the test completes.
```ruby
FOO = 42
hide_const("FOO")
FOO => NameError: uninitialized constant FOO
```
Like stubbed constants, names must be fully qualified.
Hiding constants that are already undefined has no effect.
```ruby
hide_const("NO_OP")
```
|
