#26414 splitted the pandas plotting code into two different modules:

• pandas.plotting: Generic plotting framework that defined an API (with docs) and is able to plot with a selectable backend (will be selectable with a pandas option)
• pandas.plotting._matplotlib: Matplotlib backend

Our tests in pandas/tests/plotting are currently testing both together (calling the pandas plotting framework, which will call the matplotlib backend). But ideally we'd like to have two different groups of tests:

• One with the current code but calling the matplotlib backend directly
• A test set of the generic pandas plotting framework, using a mock backend (needs to be implemented)

@jreback let me know if this makes sense to you