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# frozen_string_literal: false
require_relative '../../spec_helper'
require 'stringio'
describe "StringIO#ungetbyte" do
it "ungets a single byte from a string starting with a single byte character" do
str = 'This is a simple string.'
io = StringIO.new("#{str}")
c = io.getc
c.should == 'T'
io.ungetbyte(83)
io.string.should == 'Shis is a simple string.'
end
it "ungets a single byte from a string in the middle of a multibyte character" do
str = "\u01a9"
io = StringIO.new(str)
b = io.getbyte
b.should == 0xc6 # First byte of UTF-8 encoding of \u01a9
io.ungetbyte(0xce) # First byte of UTF-8 encoding of \u03a9
io.string.should == "\u03a9"
end
it "constrains the value of a numeric argument to a single byte" do
str = 'This is a simple string.'
io = StringIO.new("#{str}")
c = io.getc
c.should == 'T'
io.ungetbyte(83 | 0xff00)
io.string.should == 'Shis is a simple string.'
end
it "ungets the bytes of a string if given a string as an argument" do
str = "\u01a9"
io = StringIO.new(str)
b = io.getbyte
b.should == 0xc6 # First byte of UTF-8 encoding of \u01a9
io.ungetbyte("\u01a9")
io.string.bytes.should == [198, 169, 169]
end
end
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