`TablePrint::Printable.default_display_methods` takes an object and returns the set of methods we're going to use to print it.  This printable_spec is testing that for various types of objects, we return the proper set of methods.  In your case, the input will be your data hash and the output will be the keys.  Very simple; input-output.  That will also help with the assertion, because you won't have the column object in the middle.  The `Printer` is a higher level object that we don't want to involve in this test.  So I would put this spec in the existing "#default_display_methods" describe block and rename `it "returns hash keys"` or something.

```ruby
methods = TablePrint::Printable.default_display_methods(data)
methods.sort.should == ['name', 'surname']
```