#!/usr/bin/env ruby

require File.expand_path(File.join(File.dirname(__FILE__), "test_helper"))

describe BinData::Skip, "when instantiating" do
  describe "with no mandatory parameters supplied" do
    it "raises an error" do
      args = {}
      lambda { BinData::Skip.new(args) }.must_raise ArgumentError
    end
  end
end

describe BinData::Skip, "with :length" do
  let(:obj) { BinData::Skip.new(:length => 5) }
  let(:io) { StringIO.new("abcdefghij") }

  it "initial state" do
    obj.must_equal ""
    obj.to_binary_s.must_equal_binary "\000" * 5
  end

  it "skips bytes" do
    obj.read(io)
    io.pos.must_equal 5
  end

  it "has expected binary representation after setting value" do
    obj.assign("123")
    obj.to_binary_s.must_equal_binary "\000" * 5
  end

  it "has expected binary representation after reading" do
    obj.read(io)
    obj.to_binary_s.must_equal_binary "\000" * 5
  end
end

describe BinData::Skip, "with :to_abs_offset" do
  BinData::Struct.new(:fields => [ [:skip, :f, { :to_abs_offset => 5 } ] ])

  let(:skip_obj) { [:skip, :f, { :to_abs_offset => 5 } ] }
  let(:io) { StringIO.new("abcdefghij") }

  it "reads skipping forward" do
    fields = [ skip_obj ]
    obj = BinData::Struct.new(:fields => fields)
    obj.read(io)
    io.pos.must_equal 5
  end

  it "reads skipping in place" do
    fields = [ [:string, :a, { :read_length => 5 }], skip_obj ]
    obj = BinData::Struct.new(:fields => fields)
    obj.read(io)
    io.pos.must_equal 5
  end

  it "does not read skipping backwards" do
    fields = [ [:string, :a, { :read_length => 10 }], skip_obj ]
    obj = BinData::Struct.new(:fields => fields)

    lambda {
      obj.read(io)
    }.must_raise BinData::ValidityError
  end

  it "writes skipping forward" do
    fields = [ skip_obj ]
    obj = BinData::Struct.new(:fields => fields)
    obj.to_binary_s.must_equal "\000\000\000\000\000"
  end

  it "reads skipping in place" do
    fields = [ [:string, :a, { :value => "abcde" }], skip_obj ]
    obj = BinData::Struct.new(:fields => fields)
    obj.to_binary_s.must_equal "abcde"
  end

  it "does not write skipping backwards" do
    fields = [ [:string, :a, { :value => "abcdefghij" }], skip_obj ]
    obj = BinData::Struct.new(:fields => fields)
    lambda {
      obj.to_binary_s
    }.must_raise BinData::ValidityError
  end
end