1 files changed, 70 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/truncate_spec.rb b/spec/ruby/library/stringio/truncate_spec.rb
new file mode 100644
index 0000000000..1023b3d13c
--- /dev/null
+++ b/spec/ruby/library/stringio/truncate_spec.rb
@@ -0,0 +1,70 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require "stringio"
+
+describe "StringIO#truncate when passed [length]" do
+  before :each do
+    @io = StringIO.new('123456789')
+  end
+
+  # TODO: Report to Ruby-Core: The RDoc says it always returns 0
+  it "returns the passed length" do
+    @io.truncate(4).should eql(4)
+    @io.truncate(10).should eql(10)
+  end
+
+  it "truncated the underlying string down to the passed length" do
+    @io.truncate(4)
+    @io.string.should == "1234"
+  end
+
+  it "does not create a copy of the underlying string" do
+    io = StringIO.new(str = "123456789")
+    io.truncate(4)
+    io.string.should equal(str)
+  end
+
+  it "does not change the position" do
+    @io.pos = 7
+    @io.truncate(4)
+    @io.pos.should eql(7)
+  end
+
+  it "can grow a string to a larger size, padding it with \\000" do
+    @io.truncate(12)
+    @io.string.should == "123456789\000\000\000"
+  end
+
+  it "raises an Errno::EINVAL when the passed length is negative" do
+    lambda { @io.truncate(-1) }.should raise_error(Errno::EINVAL)
+    lambda { @io.truncate(-10) }.should raise_error(Errno::EINVAL)
+  end
+
+  it "tries to convert the passed length to an Integer using #to_int" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(4)
+
+    @io.truncate(obj)
+    @io.string.should == "1234"
+  end
+
+  it "returns the passed length Object, NOT the result of #to_int" do
+    obj = mock("to_int")
+    obj.should_receive(:to_int).and_return(4)
+    @io.truncate(obj).should equal(obj)
+  end
+
+  it "raises a TypeError when the passed length can't be converted to an Integer" do
+    lambda { @io.truncate(Object.new) }.should raise_error(TypeError)
+  end
+end
+
+describe "StringIO#truncate when self is not writable" do
+  it "raises an IOError" do
+    io = StringIO.new("test", "r")
+    lambda { io.truncate(2) }.should raise_error(IOError)
+
+    io = StringIO.new("test")
+    io.close_write
+    lambda { io.truncate(2) }.should raise_error(IOError)
+  end
+end