Add (partial) spec for IO::Buffer#valid?

Author: trinistr

core/io/buffer/valid_spec.rb

@@ -0,0 +1,119 @@
+require_relative '../../../spec_helper'
+
+describe "IO::Buffer#valid?" do
+ after :each do
+ @buffer&.free
+ @buffer = nil
+ end
+
+ # Non-slices are always valid
+ context "with a non-slice buffer" do
+ it "is true for a regular buffer" do
+ @buffer = IO::Buffer.new(4)
+ @buffer.valid?.should be_true
+ end
+
+ it "is true for a 0-size buffer" do
+ @buffer = IO::Buffer.new(0)
+ @buffer.valid?.should be_true
+ end
+
+ it "is true for a freed buffer" do
+ @buffer = IO::Buffer.new(4)
+ @buffer.free
+ @buffer.valid?.should be_true
+ end
+
+ it "is true for a freed file-backed buffer" do
+ File.open(__FILE__, "r") do |file|
+ @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+ @buffer.valid?.should be_true
+ @buffer.free
+ @buffer.valid?.should be_true
+ end
+ end
+
+ it "is true for a freed string-backed buffer" do
+ @buffer = IO::Buffer.for("hello")
+ @buffer.valid?.should be_true
+ @buffer.free
+ @buffer.valid?.should be_true
+ end
+ end
+
+ # "A buffer becomes invalid if it is a slice of another buffer (or string)
+ # which has been freed or re-allocated at a different address."
+ context "with a slice" do
+ it "is true for a slice of a live buffer" do
+ @buffer = IO::Buffer.new(4)
+ slice = @buffer.slice(0, 2)
+ slice.valid?.should be_true
+ end
+
+ context "when buffer is resized" do
+ platform_is_not :windows do
+ it "is true when slice is still inside the buffer" do
+ @buffer = IO::Buffer.new(4)
+ slice = @buffer.slice(1, 2)
+ @buffer.resize(3)
+ slice.valid?.should be_true
+ end
+ end
+
+ it "is false when slice becomes outside the buffer" do
+ @buffer = IO::Buffer.new(4)
+ slice = @buffer.slice(2, 2)
+ @buffer.resize(3)
+ slice.valid?.should be_false
+ end
+
+ platform_is_not :linux do
+ # This test does not cause a copy-resize on Linux.
+ # It MAY cause the buffer to move, but there is no guarantee.
+ it "is false when buffer is copied on resize" do
+ @buffer = IO::Buffer.new(4, IO::Buffer::MAPPED)
+ slice = @buffer.slice(0, 2)
+ @buffer.resize(8)
+ slice.valid?.should be_false
+ end
+ end
+ end
+
+ it "is false for a slice of a transferred buffer" do
+ buffer = IO::Buffer.new(4)
+ slice = buffer.slice(0, 2)
+ @buffer = buffer.transfer
+ slice.valid?.should be_false
+ end
+
+ it "is false for a slice of a freed buffer" do
+ @buffer = IO::Buffer.new(4)
+ slice = @buffer.slice(0, 2)
+ @buffer.free
+ slice.valid?.should be_false
+ end
+
+ it "is false for a slice of a freed file-backed buffer" do
+ File.open(__FILE__, "r") do |file|
+ @buffer = IO::Buffer.map(file, nil, 0, IO::Buffer::READONLY)
+ slice = @buffer.slice(0, 2)
+ slice.valid?.should be_true
+ @buffer.free
+ slice.valid?.should be_false
+ end
+ end
+
+ it "is true for a slice of a freed string-backed buffer while string is alive" do
+ @buffer = IO::Buffer.for("alive")
+ slice = @buffer.slice(0, 2)
+ slice.valid?.should be_true
+ @buffer.free
+ slice.valid?.should be_true
+ end
+
+ # There probably should be a test with a garbage-collected string,
+ # but it's not clear how to force that.
+
+ it "needs to be reviewed for spec completeness"
+ end
+end