add crop tests

tests/test_fx.py

@@ -0,0 +1,39 @@
+import pytest
+from moviepy.editor import *
+
+from moviepy.video.fx.crop import crop
+
+import os
+import sys
+sys.path.append("tests")
+import download_media
+from test_helper import TRAVIS, TMP_DIR
+
+
+def test_download_media(capsys):
+    with capsys.disabled():
+       download_media.download()
+
+def test_crop():
+    clip = VideoFileClip("media/big_buck_bunny_432_433.webm")
+
+    clip1=crop(clip)   #ie, no cropping (just tests all default values)
+    clip1.write_videofile(os.path.join(TMP_DIR, "clip1.webm"))
+
+    clip2=crop(clip, x1=50, y1=60, x2=460, y2=275)
+    clip2.write_videofile(os.path.join(TMP_DIR, "clip2.webm"))
+
+    clip3=crop(clip, y1=30)  #remove part above y=30
+    clip3.write_videofile(os.path.join(TMP_DIR, "clip3.webm"))
+
+    clip4=crop(clip, x1=10, width=200) # crop a rect that has width=200
+    clip4.write_videofile(os.path.join(TMP_DIR, "clip4.webm"))
+
+    clip5=crop(clip, x_center=300, y_center=400, width=50, height=150)
+    clip5.write_videofile(os.path.join(TMP_DIR, "clip5.webm"))
+
+    clip6=crop(clip, x_center=300, width=400, y1=100, y2=600)
+    clip6.write_videofile(os.path.join(TMP_DIR, "clip6.webm"))
+
+if __name__ == '__main__':
+   pytest.main()