Code review comment for lp:~mandel/ubuntuone-windows-installer/uninstall-old-app

The code in the existent is_old_beta_installed should reuse the newly added get_property_for_product, so we do not add code duplication. Likewise, tests should be refactored so there is no duplication there (I'm talking about _assert_get_product_property and _assert_is_old_beta_installed).