ruby--ruby/spec/ruby/library/stringio/seek_spec.rb

require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

describe "StringIO#seek" do
  before :each do
    @io = StringIO.new("12345678")
  end

  it "seeks from the current position when whence is IO::SEEK_CUR" do
    @io.pos = 1
    @io.seek(1, IO::SEEK_CUR)
    @io.pos.should eql(2)

    @io.seek(-1, IO::SEEK_CUR)
    @io.pos.should eql(1)
  end

  it "seeks from the end of self when whence is IO::SEEK_END" do
    @io.seek(3, IO::SEEK_END)
    @io.pos.should eql(11) # Outside of the StringIO's content

    @io.seek(-2, IO::SEEK_END)
    @io.pos.should eql(6)
  end

  it "seeks to an absolute position when whence is IO::SEEK_SET" do
    @io.seek(5, IO::SEEK_SET)
    @io.pos.should == 5

    @io.pos = 3
    @io.seek(5, IO::SEEK_SET)
    @io.pos.should == 5
  end

  it "raises an Errno::EINVAL error on negative amounts when whence is IO::SEEK_SET" do
    lambda { @io.seek(-5, IO::SEEK_SET) }.should raise_error(Errno::EINVAL)
  end

  it "raises an Errno::EINVAL error on incorrect whence argument" do
    lambda { @io.seek(0, 3) }.should raise_error(Errno::EINVAL)
    lambda { @io.seek(0, -1) }.should raise_error(Errno::EINVAL)
    lambda { @io.seek(0, 2**16) }.should raise_error(Errno::EINVAL)
    lambda { @io.seek(0, -2**16) }.should raise_error(Errno::EINVAL)
  end

  it "tries to convert the passed Object to a String using #to_int" do
    obj = mock("to_int")
    obj.should_receive(:to_int).and_return(2)
    @io.seek(obj)
    @io.pos.should eql(2)
  end

  it "raises a TypeError when the passed Object can't be converted to an Integer" do
    lambda { @io.seek(Object.new) }.should raise_error(TypeError)
  end
end

describe "StringIO#seek when self is closed" do
  before :each do
    @io = StringIO.new("example")
    @io.close
  end

  it "raises an IOError" do
    lambda { @io.seek(5) }.should raise_error(IOError)
  end
end