add test for mpl figure preservation

tests/test_mpl.py

@@ -0,0 +1,78 @@
+from xontrib import mplhooks
+import numpy as np
+import matplotlib
+import matplotlib.pyplot as plt
+
+
+# some default settings that are temporarily changed by mpl
+FONT_SIZE    = 22
+FACE_COLOR   = (0.0, 1.0, 0.0, 1.0)
+TIGHT_LAYOUT = False
+
+
+def create_figure():
+    """Simply create a figure with the default settings"""
+    f, ax = plt.subplots()
+    ax.plot(np.arange(20), np.arange(20))
+    # set the figure parameters such that mpl will require changes
+    f.set_tight_layout(TIGHT_LAYOUT)
+    f.set_facecolor(FACE_COLOR)
+    matplotlib.rcParams.update({'font.size': FONT_SIZE})
+    return f
+
+
+def test_mpl_preserve_font_size():
+    """Make sure that matplotlib preserves font size settings"""
+    f = create_figure()
+    width, height = f.canvas.get_width_height()
+    s = mplhooks.figure_to_rgb_array(f, 0.5*width, 0.5*height)
+    exp = FONT_SIZE
+    obs = matplotlib.rcParams['font.size']
+    plt.close(f)
+    assert exp == obs
+
+
+def test_mpl_preserve_tight_layout():
+    """Make sure that the figure preserves tight layout settings"""
+    f = create_figure()
+    width, height = f.canvas.get_width_height()
+    s = mplhooks.figure_to_rgb_array(f, 0.5*width, 0.5*height)
+    exp = TIGHT_LAYOUT
+    obs = f.get_tight_layout()
+    plt.close(f)
+    assert exp == obs
+
+
+def test_mpl_preserve_face_color():
+    """Make sure that the figure preserves face color settings"""
+    f = create_figure()
+    width, height = f.canvas.get_width_height()
+    s = mplhooks.figure_to_rgb_array(f, 0.5*width, 0.5*height)
+    exp = FACE_COLOR
+    obs = f.get_facecolor()
+    plt.close(f)
+    assert exp == obs
+
+
+def test_mpl_preserve_width():
+    """Make sure that the figure preserves width settings"""
+    f = create_figure()
+    width, height = f.canvas.get_width_height()
+    s = mplhooks.figure_to_rgb_array(f, 0.5*width, 0.5*height)
+    exp = width
+    newwidth, newheight = f.canvas.get_width_height()
+    obs = newwidth
+    plt.close(f)
+    assert exp == obs
+
+
+def test_mpl_preserve_height():
+    """Make sure that the figure preserves height settings"""
+    f = create_figure()
+    width, height = f.canvas.get_width_height()
+    s = mplhooks.figure_to_rgb_array(f, 0.5*width, 0.5*height)
+    exp = height
+    newwidth, newheight = f.canvas.get_width_height()
+    obs = newheight
+    plt.close(f)
+    assert exp == obs