require_relative '../../spec_helper'

describe "String#unpack" do
  it "raises a TypeError when passed nil" do
    -> { "abc".unpack(nil) }.should.raise(TypeError)
  end

  it "raises a TypeError when passed an Integer" do
    -> { "abc".unpack(1) }.should.raise(TypeError)
  end

  it "starts unpacking from the given offset" do
    "abc".unpack("CC", offset: 1).should == [98, 99]
  end

  it "traits offset as a bytes offset" do
    "؈".unpack("CC").should == [216, 136]
    "؈".unpack("CC", offset: 1).should == [136, nil]
  end

  describe "when the offset is negative" do
    ruby_version_is "4.1" do
      it "starts unpacking from the end" do
        "abc".unpack("CC", offset: -2).should == [98, 99]
      end

      it "raises an ArgumentError if it is less than -length" do
        -> { "a".unpack("C", offset: -2) }.should.raise(ArgumentError, "offset outside of string")
      end
    end

    ruby_version_is ""..."4.1" do
      it "raises an ArgumentError" do
        -> { "a".unpack("C", offset: -1) }.should.raise(ArgumentError, "offset can't be negative")
      end
    end
  end

  it "returns nil if the offset is at the end of the string" do
    "a".unpack("C", offset: 1).should == [nil]
  end

  it "raises an ArgumentError when the offset is larger than the string" do
    -> { "a".unpack("C", offset: 2) }.should.raise(ArgumentError, "offset outside of string")
  end
end