Using ipympl logic inside python shell or ipython?

[codingS3b]

I have a class that inherits from the ipywidgets.widgets.VBox and adds a figure.canvas instance of a matplotlib figure to its children like so:

import matplotlib.pyplot as plt
from ipywidgets import widgets

plt.ioff()

class MyVis(widgets.VBox):
    def __init__(self):
        super().__init__()
        self.fig = plt.figure()
        self.children = [self.fig.canvas]

m = MyVis()

This works fine when I use this class within jupyter notebooks using the %matplotlib widget magic before executing the above code.
When executed within ipython I get
TraitError: Element of the 'children' trait of a MyVis instance must be a Widget, but a value of <matplotlib.backends.backend_tkagg.FigureCanvasTkAgg object at 0x7f0c48d731d0> <class 'matplotlib.backends.backend_tkagg.FigureCanvasTkAgg'> was specified.
since of course ipympl and its magic are not active.

Since I also want to have unit-tests for this class (and others that make use of this class) using pytest, it would be nice to get around this problem.
Can I enable the ipympl way of handling figures somehow in the python shell (similar to using the %matplotlib widget magic in the notebook) that would allow my tests to run?