[Stub class constants] Stub class constants in RSpec tests

stub_const.rb

# Stubbing a single class constant is a little finicky and can remove all constants of a class if not done right

MyClass::MY_CONSTANT_1 #=> 'foo'
MyClass::MY_CONSTANT_2 #=> 'bar'



# METHOD 1 (PREFERRED)
before(:example) do
  stub_const('MyClass', MyClass)
  stub_const('MyClass::MY_CONSTANT_1', 'baz')
end

MyClass::MY_CONSTANT_1 #=> 'baz'
MyClass::MY_CONSTANT_2 #=> 'bar'



# METHOD 2 (NOT AS GOOD)
around(:example) do |example|
  # Stub constant
  original = MyClass.send(:remove_const, :MY_CONSTANT_1)
  MyClass.const_set(:MY_CONSTANT_1, 'baz')
  
  example.run
  
  # Put original value back again
  MyClass.send(:remove_const, :MY_CONSTANT_1)
  MyClass.const_set(:MY_CONSTANT_1, original)
end

MyClass::MY_CONSTANT_1 #=> 'baz'
MyClass::MY_CONSTANT_2 #=> 'bar'



# WHAT *NOT* TO DO:
before(:example) do
  stub_const('MyClass::MY_CONSTANT_1', 'baz')
end
MyClass::MY_CONSTANT_1 #=> 'baz'
MyClass::MY_CONSTANT_2 #=> NameError Exception: uninitialized constant MyClass::MY_CONSTANT_2