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rails--rails/activesupport/test/descendants_tracker_test.rb
Xavier Noria 340b39ea31 Remove autoloading logic from AS::DescendantsTracker
The descendants tracker is a generic tracker that you can use anywhere.
In particular, outside Rails applications.

Should provide API to clear only a subset of classes, but in my view
should know nothing about autoloading. That is a concern of client code.
2021-08-23 00:24:26 +02:00

98 lines
3.1 KiB
Ruby

# frozen_string_literal: true
require_relative "abstract_unit"
require "set"
require "active_support/descendants_tracker"
class DescendantsTrackerTest < ActiveSupport::TestCase
setup do
@original_state = ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants").dup
@original_state.each { |k, v| @original_state[k] = v.dup }
ActiveSupport::DescendantsTracker.clear
eval <<~RUBY
class Parent
extend ActiveSupport::DescendantsTracker
end
class Child1 < Parent
end
class Child2 < Parent
end
class Grandchild1 < Child1
end
class Grandchild2 < Child1
end
RUBY
end
teardown do
ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants").replace(@original_state)
%i(Parent Child1 Child2 Grandchild1 Grandchild2).each do |name|
DescendantsTrackerTest.send(:remove_const, name)
end
end
test ".descendants" do
assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2], Parent.descendants
assert_equal_sets [Grandchild1, Grandchild2], Child1.descendants
assert_equal_sets [], Child2.descendants
end
test ".descendants with garbage collected classes" do
# The Ruby GC (and most other GCs for that matter) are not fully precise.
# When GC is run, the whole stack is scanned to mark any object reference
# in registers. But some of these references might simply be leftovers from
# previous method calls waiting to be overridden, and there's no definite
# way to clear them. By executing this code in a distinct thread, we ensure
# that such references are on a stack that will be entirely garbage
# collected, effectively working around the problem.
Thread.new do
child_klass = Class.new(Parent)
assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2, child_klass], Parent.descendants
end.join
# Calling `GC.start` 4 times should trigger a full GC run
4.times do
GC.start
end
assert_equal_sets [Child1, Grandchild1, Grandchild2, Child2], Parent.descendants
end
test ".direct_descendants" do
assert_equal_sets [Child1, Child2], Parent.direct_descendants
assert_equal_sets [Grandchild1, Grandchild2], Child1.direct_descendants
assert_equal_sets [], Child2.direct_descendants
end
test ".subclasses" do
[Parent, Child1, Child2].each do |klass|
assert_equal klass.direct_descendants, klass.subclasses
end
end
test ".clear deletes all state" do
ActiveSupport::DescendantsTracker.clear
assert_empty ActiveSupport::DescendantsTracker.class_eval("@@direct_descendants")
end
test ".clear(only) deletes the given classes only" do
ActiveSupport::DescendantsTracker.clear(only: Set[Child2, Grandchild1])
assert_equal_sets [Child1, Grandchild2], Parent.descendants
assert_equal_sets [Grandchild2], Child1.descendants
assert_equal_sets [Child1], Parent.direct_descendants
assert_equal_sets [Grandchild2], Child1.direct_descendants
end
private
def assert_equal_sets(expected, actual)
assert_equal Set.new(expected), Set.new(actual)
end
end