1 files changed, 23 insertions, 0 deletions
diff --git a/spec/ruby/core/io/buffer/external_spec.rb b/spec/ruby/core/io/buffer/external_spec.rb
new file mode 100644
index 0000000000..18b2ee0d06
--- /dev/null
+++ b/spec/ruby/core/io/buffer/external_spec.rb
@@ -0,0 +1,23 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#external?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is true for a buffer with externally-managed memory" do
+    @buffer = IO::Buffer.for("string")
+    @buffer.external?.should == true
+  end
+
+  it "is false for a buffer with self-managed memory" do
+    @buffer = IO::Buffer.new(12, IO::Buffer::MAPPED)
+    @buffer.external?.should == false
+  end
+
+  it "is false for a null buffer" do
+    @buffer = IO::Buffer.new(0)
+    @buffer.external?.should == false
+  end
+end