Unit test matplotlib's ginput

Question

I know there might be a lot of issues related with testing matplotlib's GUI. I found some advice here: How can I write unit tests against code that uses matplotlib?

I use matplotlib to generate "user" input for my code. How can I mock this input generation?

In the following, I describe my function.

import numpy as np
import matplotlib.pyplot as plt

def select_pixel(xRes, yRes):
    pos = []
    pos2d = np.zeros([xRes, yRes])

    fig, axes = plt.subplots()
    axes.set_title('Click to select pixels, middle mouse button to finish')
    axes.imshow(pos2d)

    # Gather selection
    val = [()]
    while len(val):
        val = plt.ginput(1, timeout=-1)
        if len(val):
            x, y = val[0]
            if (x is not None) & (y is not None):
                pos.append([int(x), int(y)])

    return pos

For this function, I want to generate a mock output with several use cases:

• No input
• A single input
• Several inputs (eventually also mocking None values?)