I've been trying to follow http://devs.valence.desire2learn.com/2013/02/15/remote-plugins-the-bookwidget-sample-2 to make sure we can get the demo running before continuing with development, however we've run into the problem where the sample instructions given don't mention a "System Test Link", and d2l won't allow us to create the widget without one.
What is this, and how can this be solved?
Edit: The system the client is using is 10.1
Looks like the "community" decided that my additions to Sarah-Beth's answer were not appropriate. So here's my edited answer in it's entirety:
The System Test Link is not a required value in order to create a new Remote Plugin. This behavior has been verified against both Desire2Learn 10.1 and 10.2 environments.
A System Test Link value is required in order to run automated tests using the Test button on the Create a New Remote Plugin form. If you click the Test button without populating that field, you will be alerted that a value must be entered in the System Test Field in order to proceed. But this alert does not prevent you from creating your Remote Plugin by clicking Save.
The only required values for a new Remote Plugin are a launch point, a name, and a build type (course builder, widget).
Note. The UI for this management tool can be a bit confusing. When you enter your information and click Save, the tool's UX prompts the browser window to reset to the top of the displayed page: if your browser window is not long enough to contain the entire form, you will not see the little message above the Save button that tells you your configuration has changed, and there's no apparent change in the form's state. Accordingly, you may think that you haven't saved anything when, in fact you have.
Provide the config for your plugin, ensure you have a launch point, a name, and a build configuration selected (at least), and click Save. Once the browser resets the viewport to the top of the form's page, you should be able to click Cancel to back out of the form and see your new plugin in the list of plugins. We are aware of the discomfort in this form and are taking steps to improve it's UX.