Module: ActiveSupport::Testing::ConstantStubbing
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Included In:
::ActionCable::Channel::TestCase ,
::ActionCable::Connection::TestCase ,
::ActionCable::TestCase ,
::ActionController::TestCase ,
::ActionDispatch::IntegrationTest ,
::ActionDispatch::SystemTestCase ,
::ActionMailbox::TestCase ,
::ActionMailer::TestCase ,
::ActionView::TestCase ,
::ActiveJob::TestCase ,
::ActiveSupport::TestCase ,
::Rails::Generators::TestCase
| |
Defined in: | activesupport/lib/active_support/testing/constant_stubbing.rb |
Instance Method Summary
-
#stub_const(mod, constant, new_value, exists: true)
Changes the value of a constant for the duration of a block.
Instance Method Details
#stub_const(mod, constant, new_value, exists: true)
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 World::List::Import::LARGE_IMPORT_THRESHOLD = 5000
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.
# File 'activesupport/lib/active_support/testing/constant_stubbing.rb', line 28
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