1 files changed, 119 insertions, 0 deletions
diff --git a/spec/ruby/core/io/ungetc_spec.rb b/spec/ruby/core/io/ungetc_spec.rb
new file mode 100644
index 0000000000..ce4cc9d346
--- /dev/null
+++ b/spec/ruby/core/io/ungetc_spec.rb
@@ -0,0 +1,119 @@
+# -*- encoding: utf-8 -*-
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "IO#ungetc" do
+  before :each do
+    @io = IOSpecs.io_fixture "lines.txt"
+
+    @empty = tmp('empty.txt')
+  end
+
+  after :each do
+    @io.close unless @io.closed?
+    rm_r @empty
+  end
+
+  it "pushes back one character onto stream" do
+    @io.getc.should == ?V
+    @io.ungetc(86)
+    @io.getc.should == ?V
+
+    @io.ungetc(10)
+    @io.getc.should == ?\n
+
+    @io.getc.should == ?o
+    @io.getc.should == ?i
+    # read the rest of line
+    @io.readline.should == "ci la ligne une.\n"
+    @io.getc.should == ?Q
+    @io.ungetc(99)
+    @io.getc.should == ?c
+  end
+
+  it "pushes back one character when invoked at the end of the stream" do
+    # read entire content
+    @io.read
+    @io.ungetc(100)
+    @io.getc.should == ?d
+  end
+
+  it "pushes back one character when invoked at the start of the stream" do
+    @io.read(0)
+    @io.ungetc(100)
+    @io.getc.should == ?d
+  end
+
+  it "pushes back one character when invoked on empty stream" do
+    touch(@empty)
+
+    File.open(@empty) { |empty|
+      empty.getc().should == nil
+      empty.ungetc(10)
+      empty.getc.should == ?\n
+    }
+  end
+
+  it "affects EOF state" do
+    touch(@empty)
+
+    File.open(@empty) { |empty|
+      empty.eof?.should == true
+      empty.getc.should == nil
+      empty.ungetc(100)
+      empty.eof?.should == false
+    }
+  end
+
+  it "adjusts the stream position" do
+    @io.pos.should == 0
+
+    # read one char
+    c = @io.getc
+    @io.pos.should == 1
+    @io.ungetc(c)
+    @io.pos.should == 0
+
+    # read all
+    @io.read
+    pos = @io.pos
+    @io.ungetc(98)
+    @io.pos.should == pos - 1
+  end
+
+  it "makes subsequent unbuffered operations to raise IOError" do
+    @io.getc
+    @io.ungetc(100)
+    lambda { @io.sysread(1) }.should raise_error(IOError)
+  end
+
+  it "does not affect the stream and returns nil when passed nil" do
+    @io.getc.should == ?V
+    @io.ungetc(nil)
+    @io.getc.should == ?o
+  end
+
+  it "puts one or more characters back in the stream" do
+    @io.gets
+    @io.ungetc("Aquí ").should be_nil
+    @io.gets.chomp.should == "Aquí Qui è la linea due."
+  end
+
+  it "calls #to_str to convert the argument if it is not an Integer" do
+    chars = mock("io ungetc")
+    chars.should_receive(:to_str).and_return("Aquí ")
+
+    @io.ungetc(chars).should be_nil
+    @io.gets.chomp.should == "Aquí Voici la ligne une."
+  end
+
+  it "returns nil when invoked on stream that was not yet read" do
+    @io.ungetc(100).should be_nil
+  end
+
+  it "raises IOError on closed stream" do
+    @io.getc
+    @io.close
+    lambda { @io.ungetc(100) }.should raise_error(IOError)
+  end
+end