2 files changed, 118 insertions, 0 deletions

diff --git a/cont.c b/cont.c
index e050deefdc..49629efd90 100644
--- a/cont.c
+++ b/cont.c
@@ -2090,10 +2090,17 @@ fiber_storage_validate_each(VALUE key, VALUE value, VALUE _argument)
 static void
 fiber_storage_validate(VALUE value)
 {
+    // nil is an allowed value and will be lazily initialized.
+    if (value == Qnil) return;
+
     if (!RB_TYPE_P(value, T_HASH)) {
         rb_raise(rb_eTypeError, "storage must be a hash");
     }
 
+    if (RB_OBJ_FROZEN(value)) {
+        rb_raise(rb_eFrozenError, "storage must not be frozen");
+    }
+
     rb_hash_foreach(value, fiber_storage_validate_each, Qundef);
 }
 
diff --git a/spec/ruby/core/fiber/storage_spec.rb b/spec/ruby/core/fiber/storage_spec.rb
new file mode 100644
index 0000000000..4adfd30d2b
--- /dev/null
+++ b/spec/ruby/core/fiber/storage_spec.rb
@@ -0,0 +1,111 @@
+require_relative '../../spec_helper'
+
+require 'fiber'
+
+describe "Fiber.new(storage:)" do
+  ruby_version_is "3.2" do
+    it "creates a Fiber with the given storage" do
+      storage = {life: 42}
+      fiber = Fiber.new(storage: storage) { Fiber.current.storage }
+      fiber.resume.should == storage
+    end
+
+    it "creates a fiber with lazily initialized storage" do
+      fiber = Fiber.new(storage: nil) {}
+      fiber.storage.should == {}
+    end
+
+    it "creates a fiber by inheriting the storage of the parent fiber" do
+      fiber = Fiber.new(storage: {life: 42}) do
+        Fiber.new { Fiber.current.storage }.resume
+      end
+      fiber.resume.should == {life: 42}
+    end
+
+    it "creates a fiber with a reference to the storage of the parent fiber" do
+      fiber = Fiber.new(storage: {life: 42}) do
+        Fiber.new(storage: false) { Fiber[:life] = 43 }.resume
+        Fiber.current.storage
+      end
+      fiber.resume.should == {life: 43}
+    end
+
+    it "cannot create a fiber with non-hash storage" do
+      -> { Fiber.new(storage: 42) {} }.should raise_error(TypeError)
+    end
+  end
+end
+
+describe "Fiber#storage" do
+  ruby_version_is "3.2" do
+    it "can clear the storage of the fiber" do
+      fiber = Fiber.new(storage: {life: 42}) { Fiber.current.storage }
+      fiber.storage = nil
+      fiber.resume.should == {}
+    end
+
+    it "can set the storage of the fiber" do
+      fiber = Fiber.new(storage: {life: 42}) { Fiber.current.storage }
+      fiber.storage = {life: 43}
+      fiber.resume.should == {life: 43}
+    end
+
+    it "can't set the storage of the fiber to non-hash" do
+      fiber = Fiber.new(storage: {life: 42}) { Fiber.current.storage }
+      -> { fiber.storage = 42 }.should raise_error(TypeError)
+    end
+
+    it "can't set the storage of the fiber to a frozen hash" do
+      fiber = Fiber.new(storage: {life: 42}) { Fiber.current.storage }
+      -> { fiber.storage = {life: 43}.freeze }.should raise_error(FrozenError)
+    end
+
+    it "can't set the storage of the fiber to a hash with non-symbol keys" do
+      fiber = Fiber.new(storage: {life: 42}) { Fiber.current.storage }
+      -> { fiber.storage = {life: 43, Object.new => 44} }.should raise_error(TypeError)
+    end
+  end
+end
+
+describe "Fiber.[]" do
+  ruby_version_is "3.2" do
+    it "returns the value of the given key in the storage of the current fiber" do
+      Fiber.new(storage: {life: 42}) { Fiber[:life] }.resume.should == 42
+    end
+
+    it "returns nil if the key is not present in the storage of the current fiber" do
+      Fiber.new(storage: {life: 42}) { Fiber[:death] }.resume.should be_nil
+    end
+
+    it "returns nil if the current fiber has no storage" do
+      Fiber.new { Fiber[:life] }.resume.should be_nil
+    end
+  end
+end
+
+describe "Fiber.[]=" do
+  ruby_version_is "3.2" do
+    it "sets the value of the given key in the storage of the current fiber" do
+      Fiber.new(storage: {life: 42}) { Fiber[:life] = 43; Fiber[:life] }.resume.should == 43
+    end
+
+    it "sets the value of the given key in the storage of the current fiber" do
+      Fiber.new(storage: {life: 42}) { Fiber[:death] = 43; Fiber[:death] }.resume.should == 43
+    end
+
+    it "sets the value of the given key in the storage of the current fiber" do
+      Fiber.new { Fiber[:life] = 43; Fiber[:life] }.resume.should == 43
+    end
+  end
+end
+
+describe "Thread.new" do
+  ruby_version_is "3.2" do
+    it "creates a thread with the storage of the current fiber" do
+      fiber = Fiber.new(storage: {life: 42}) do
+        Thread.new { Fiber.current.storage }.value
+      end
+      fiber.resume.should == {life: 42}
+    end
+  end
+end