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Contents
# frozen_string_literal: true
module ActiveSupport
module Testing
module ConstantStubbing
# Changes the value of a constant for the duration of a block. Example:
#
# # World::List::Import::LARGE_IMPORT_THRESHOLD = 5000
# stub_const(World::List::Import, :LARGE_IMPORT_THRESHOLD, 1) do
# assert_equal 1, World::List::Import::LARGE_IMPORT_THRESHOLD
# end
#
# assert_equal 5000, World::List::Import::LARGE_IMPORT_THRESHOLD
#
# Using this method rather than forcing <tt>World::List::Import::LARGE_IMPORT_THRESHOLD = 5000</tt> prevents
# warnings from being thrown, and ensures that the old value is returned after the test has completed.
#
# If the constant doesn't already exists, but you need it set for the duration of the block
# you can do so by passing `exists: false`.
#
# stub_const(object, :SOME_CONST, 1, exists: false) do
# assert_equal 1, SOME_CONST
# end
#
# Note: Stubbing a const will stub it across all threads. So if you have concurrent threads
# (like separate test suites running in parallel) that all depend on the same constant, it's possible
# divergent stubbing will trample on each other.
def stub_const(mod, constant, new_value, exists: true)
if exists
begin
old_value = mod.const_get(constant, false)
mod.send(:remove_const, constant)
mod.const_set(constant, new_value)
yield
ensure
mod.send(:remove_const, constant)
mod.const_set(constant, old_value)
end
else
if mod.const_defined?(constant)
raise NameError, "already defined constant #{constant} in #{mod.name}"
end
begin
mod.const_set(constant, new_value)
yield
ensure
mod.send(:remove_const, constant)
end
end
end
end
end
end
Version data entries
25 entries across 25 versions & 3 rubygems