Add spec for IO::Buffer#locked and #locked?

Author: trinistr

core/io/buffer/locked_spec.rb

@@ -0,0 +1,75 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#locked" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  context "when buffer is locked" do
+    it "allows reading and writing operations on the buffer" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.set_string("test")
+      @buffer.locked do
+        @buffer.get_string.should == "test"
+        @buffer.set_string("meat")
+      end
+      @buffer.get_string.should == "meat"
+    end
+
+    it "disallows operations changing buffer itself, raising IO::Buffer::LockedError" do
+      @buffer = IO::Buffer.new(4)
+      @buffer.locked do
+        # Just an example, each method is responsible for checking the lock state.
+        -> { @buffer.resize(8) }.should raise_error(IO::Buffer::LockedError)
+      end
+    end
+  end
+
+  it "disallows reentrant locking, raising IO::Buffer::LockedError" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      -> { @buffer.locked {} }.should raise_error(IO::Buffer::LockedError, "Buffer already locked!")
+    end
+  end
+
+  it "does not propagate to buffer's slices" do
+    @buffer = IO::Buffer.new(4)
+    slice = @buffer.slice(0, 2)
+    @buffer.locked do
+      @buffer.locked?.should be_true
+      slice.locked?.should be_false
+      slice.locked { slice.locked?.should be_true }
+    end
+  end
+
+  it "does not propagate backwards from buffer's slices" do
+    @buffer = IO::Buffer.new(4)
+    slice = @buffer.slice(0, 2)
+    slice.locked do
+      slice.locked?.should be_true
+      @buffer.locked?.should be_false
+      @buffer.locked { @buffer.locked?.should be_true }
+    end
+  end
+end
+
+describe "IO::Buffer#locked?" do
+  after :each do
+    @buffer&.free
+    @buffer = nil
+  end
+
+  it "is false by default" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked?.should be_false
+  end
+
+  it "is true only inside of #locked block" do
+    @buffer = IO::Buffer.new(4)
+    @buffer.locked do
+      @buffer.locked?.should be_true
+    end
+    @buffer.locked?.should be_false
+  end
+end