Introduce `Fiber#storage` for inheritable fiber-scoped variables. (#6612)

1 files changed, 101 insertions, 0 deletions

diff --git a/test/fiber/test_storage.rb b/test/fiber/test_storage.rb
new file mode 100644
index 0000000000..0a6942617c
--- /dev/null
+++ b/test/fiber/test_storage.rb
@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+require 'test/unit'
+
+class TestFiberStorage < Test::Unit::TestCase
+  def test_storage
+    Fiber.new do
+      Fiber[:x] = 10
+      assert_kind_of Hash, Fiber.current.storage
+      assert_predicate Fiber.current.storage, :any?
+    end.resume
+  end
+
+  def test_storage_inherited
+    Fiber.new do
+      Fiber[:foo] = :bar
+
+      Fiber.new do
+        assert_equal :bar, Fiber[:foo]
+        Fiber[:bar] = :baz
+      end.resume
+
+      assert_nil Fiber[:bar]
+    end.resume
+  end
+
+  def test_variable_assignment
+    Fiber.new do
+      Fiber[:foo] = :bar
+      assert_equal :bar, Fiber[:foo]
+    end.resume
+  end
+
+  def test_storage_assignment
+    Fiber.new do
+      Fiber.current.storage = {foo: :bar}
+      assert_equal :bar, Fiber[:foo]
+    end.resume
+  end
+
+  def test_inherited_storage
+    Fiber.new do
+      Fiber.current.storage = {foo: :bar}
+      f = Fiber.new do
+        assert_equal :bar, Fiber[:foo]
+      end
+      f.resume
+    end.resume
+  end
+
+  def test_enumerator_inherited_storage
+    Fiber.new do
+      Fiber[:item] = "Hello World"
+
+      enumerator = Enumerator.new do |out|
+        out << Fiber.current
+        out << Fiber[:item]
+      end
+
+      # The fiber within the enumerator is not equal to the current...
+      assert_not_equal Fiber.current, enumerator.next
+
+      # But it inherited the storage from the current fiber:
+      assert_equal "Hello World", enumerator.next
+    end.resume
+  end
+
+  def test_thread_inherited_storage
+    Fiber.new do
+      Fiber[:x] = 10
+
+      x = Thread.new do
+        Fiber[:y] = 20
+        Fiber[:x]
+      end.value
+
+      assert_equal 10, x
+      assert_equal nil, Fiber[:y]
+    end.resume
+  end
+
+  def test_enumerator_count
+    Fiber.new do
+      Fiber[:count] = 0
+
+      enumerator = Enumerator.new do |y|
+        # Since the fiber is implementation detail, the storage are shared with the parent:
+        Fiber[:count] += 1
+        y << Fiber[:count]
+      end
+
+      assert_equal 1, enumerator.next
+      assert_equal 1, Fiber[:count]
+    end.resume
+  end
+
+  def test_storage_assignment_type_error
+    assert_raise(TypeError) do
+      Fiber.new(storage: {Object.new => "bar"}) {}
+    end
+  end
+end