add doc example to tests

moviepy/video/compositing/concatenate.py

@@ -82,12 +82,15 @@ def make_frame(t):
             i = max([i for i, e in enumerate(tt) if e <= t])
             return clips[i].get_frame(t - tt[i])
 
+        def get_mask(c):
+            mask = c.mask or ColorClip([1, 1], col=1, ismask=True)
+            if mask.duration is None:
+               mask.duration = c.duration
+            return mask
+
         result = VideoClip(ismask = ismask, make_frame = make_frame)
         if any([c.mask is not None for c in clips]):
-            masks = [c.mask.set_duration(c.duration) if (c.mask is not None) else
-                     ColorClip([1,1], col=1, ismask=True, duration=c.duration)
-                 #ColorClip(c.size, col=1, ismask=True).set_duration(c.duration)
-                     for c in clips]
+            masks = [get_mask(c) for c in clips]
             result.mask = concatenate_videoclips(masks, method="chain", ismask=True)
             result.clips = clips
     elif method == "compose":

tests/test_examples.py

@@ -0,0 +1,44 @@
+import pytest
+from moviepy.editor import *
+import moviepy.video.tools.cuts as cuts
+
+import sys
+sys.path.append("tests")
+import download_media
+
+def test_download_media(capsys):
+    with capsys.disabled():
+       download_media.download()
+
+def test_matplotlib():
+    #for now, python 3.5 installs a version of matplotlib that complains
+    #about $DISPLAY variable, so lets just ignore for now.
+    if sys.version_info < (3,4):
+       return
+
+    if sys.version_info.major == 3 and sys.version_info.minor == 5:
+       return
+
+    import matplotlib.pyplot as plt
+    import numpy as np
+    from moviepy.editor import VideoClip
+    from moviepy.video.io.bindings import mplfig_to_npimage
+
+    x = np.linspace(-2, 2, 200)
+
+    duration = 2
+
+    fig, ax = plt.subplots()
+
+    def make_frame(t):
+        ax.clear()
+        ax.plot(x, np.sinc(x**2) + np.sin(x + 2*np.pi/duration * t), lw=3)
+        ax.set_ylim(-1.5, 2.5)
+        return mplfig_to_npimage(fig)
+
+    animation = VideoClip(make_frame, duration=duration)
+    animation.write_gif('/tmp/matplotlib.gif', fps=20)
+
+
+if __name__ == '__main__':
+   pytest.main()