diff --git a/core/fiber/blocking_spec.rb b/core/fiber/blocking_spec.rb
new file mode 100644
index 0000000000..5ae5fbd577
--- /dev/null
+++ b/core/fiber/blocking_spec.rb
@@ -0,0 +1,62 @@
+require_relative '../../spec_helper'
+require_relative 'shared/blocking'
+
+ruby_version_is "3.0" do
+  require "fiber"
+
+  describe "Fiber.blocking?" do
+    it_behaves_like :non_blocking_fiber, -> { Fiber.blocking? }
+
+    context "when fiber is blocking" do
+      context "root Fiber of the main thread" do
+        it "returns 1 for blocking: true" do
+          fiber = Fiber.new(blocking: true) { Fiber.blocking? }
+          blocking = fiber.resume
+
+          blocking.should == 1
+        end
+      end
+
+      context "root Fiber of a new thread" do
+        it "returns 1 for blocking: true" do
+          thread = Thread.new do
+            fiber = Fiber.new(blocking: true) { Fiber.blocking? }
+            blocking = fiber.resume
+
+            blocking.should == 1
+          end
+
+          thread.join
+        end
+      end
+    end
+  end
+
+  describe "Fiber#blocking?" do
+    it_behaves_like :non_blocking_fiber, -> { Fiber.current.blocking? }
+
+    context "when fiber is blocking" do
+      context "root Fiber of the main thread" do
+        it "returns true for blocking: true" do
+          fiber = Fiber.new(blocking: true) { Fiber.current.blocking? }
+          blocking = fiber.resume
+
+          blocking.should == true
+        end
+      end
+
+      context "root Fiber of a new thread" do
+        it "returns true for blocking: true" do
+          thread = Thread.new do
+            fiber = Fiber.new(blocking: true) { Fiber.current.blocking? }
+            blocking = fiber.resume
+
+            blocking.should == true
+          end
+
+          thread.join
+        end
+      end
+    end
+  end
+end
diff --git a/core/fiber/shared/blocking.rb b/core/fiber/shared/blocking.rb
new file mode 100644
index 0000000000..21707e1ea7
--- /dev/null
+++ b/core/fiber/shared/blocking.rb
@@ -0,0 +1,41 @@
+describe :non_blocking_fiber, shared: true do
+  context "root Fiber of the main thread" do
+    it "returns false" do
+      fiber = Fiber.new { @method.call }
+      blocking = fiber.resume
+
+      blocking.should == false
+    end
+
+    it "returns false for blocking: false" do
+      fiber = Fiber.new(blocking: false) { @method.call }
+      blocking = fiber.resume
+
+      blocking.should == false
+    end
+  end
+
+  context "root Fiber of a new thread" do
+    it "returns false" do
+      thread = Thread.new do
+        fiber = Fiber.new { @method.call }
+        blocking = fiber.resume
+
+        blocking.should == false
+      end
+
+      thread.join
+    end
+
+    it "returns false for blocking: false" do
+      thread = Thread.new do
+        fiber = Fiber.new(blocking: false) { @method.call }
+        blocking = fiber.resume
+
+        blocking.should == false
+      end
+
+      thread.join
+    end
+  end
+end