Create test for MultiCursor

ianhi · ianhi · commit 699edf77257e · 2021-03-07T13:28:56.000-05:00
diff --git a/lib/matplotlib/tests/test_widgets.py b/lib/matplotlib/tests/test_widgets.py
@@ -2,7 +2,7 @@
 import matplotlib.widgets as widgets
 import matplotlib.pyplot as plt
 from matplotlib.testing.decorators import image_comparison
-from matplotlib.testing.widgets import do_event, get_ax
+from matplotlib.testing.widgets import do_event, get_ax, mock_event
 
 from numpy.testing import assert_allclose
 
@@ -460,3 +460,43 @@ def test_polygon_selector():
                       + polygon_place_vertex(50, 150)
                       + polygon_place_vertex(50, 50))
     check_polygon_selector(event_sequence, expected_result, 1)
+
+
+@pytest.mark.parametrize(
+    "horizOn, vertOn",
+    [(True, True), (True, False), (False, True)],
+)
+def test_MultiCursor(horizOn, vertOn):
+    fig, (ax1, ax2, ax3) = plt.subplots(3, sharex=True)
+
+    # useblit=false to avoid having to draw the figure to cache the renderer
+    multi = widgets.MultiCursor(
+        fig.canvas, (ax1, ax2), useblit=False, horizOn=horizOn, vertOn=vertOn
+    )
+
+    # Only two of the axes should have a line drawn on them.
+    if vertOn:
+        assert len(multi.vlines) == 2
+    if horizOn:
+        assert len(multi.hlines) == 2
+
+    # mock a motion_notify_event
+    # Can't use `do_event` as that helper requires the widget
+    # to have a single .ax attribute.
+    event = mock_event(ax1, xdata=.5, ydata=.25)
+    multi.onmove(event)
+
+    # the lines in the first two ax should both move
+    for l in multi.vlines:
+        assert l.get_xdata() == (.5, .5)
+    for l in multi.hlines:
+        assert l.get_ydata() == (.25, .25)
+
+    # test a move event in an axes not part of the MultiCursor
+    # the lines in ax1 and ax2 should not have moved.
+    event = mock_event(ax3, xdata=.75, ydata=.75)
+    multi.onmove(event)
+    for l in multi.vlines:
+        assert l.get_xdata() == (.5, .5)
+    for l in multi.hlines:
+        assert l.get_ydata() == (.25, .25)
