1 files changed, 54 insertions, 0 deletions
diff --git a/spec/ruby/core/io/ungetbyte_spec.rb b/spec/ruby/core/io/ungetbyte_spec.rb
new file mode 100644
index 0000000000..e0615cd76c
--- /dev/null
+++ b/spec/ruby/core/io/ungetbyte_spec.rb
@@ -0,0 +1,54 @@
+require_relative '../../spec_helper'
+
+describe "IO#ungetbyte" do
+  before :each do
+    @name = tmp("io_ungetbyte")
+    touch(@name) { |f| f.write "a" }
+    @io = new_io @name, "r"
+  end
+
+  after :each do
+    @io.close unless @io.closed?
+    rm_r @name
+  end
+
+  it "does nothing when passed nil" do
+    @io.ungetbyte(nil).should == nil
+    @io.getbyte.should == 97
+  end
+
+  it "puts back each byte in a String argument" do
+    @io.ungetbyte("cat").should == nil
+    @io.getbyte.should == 99
+    @io.getbyte.should == 97
+    @io.getbyte.should == 116
+    @io.getbyte.should == 97
+  end
+
+  it "calls #to_str to convert the argument" do
+    str = mock("io ungetbyte")
+    str.should_receive(:to_str).and_return("dog")
+
+    @io.ungetbyte(str).should == nil
+    @io.getbyte.should == 100
+    @io.getbyte.should == 111
+    @io.getbyte.should == 103
+    @io.getbyte.should == 97
+  end
+
+  it "never raises RangeError" do
+    for i in [4095, 0x4f7574206f6620636861722072616e67ff] do
+      @io.ungetbyte(i).should == nil
+      @io.getbyte.should == 255
+    end
+  end
+
+  it "raises IOError on stream not opened for reading" do
+    -> { STDOUT.ungetbyte(42) }.should.raise(IOError, "not opened for reading")
+  end
+
+  it "raises an IOError if the IO is closed" do
+    @io.close
+    -> { @io.ungetbyte(42) }.should.raise(IOError)
+  end
+end