Issue Zulko#596 and Zulko#598: Updated test to support close().

Also changed test to meet Issue Zulko#598, but that is also being done in
PR#585, so will require a merge.

tests/test_TextClip.py

@@ -3,9 +3,9 @@
 import pytest
 from moviepy.video.fx.blink import blink
 from moviepy.video.VideoClip import TextClip
-from test_helper import TMP_DIR, TRAVIS
 
 sys.path.append("tests")
+from test_helper import TMP_DIR, TRAVIS
 
 def test_duration():
     #TextClip returns the following error under Travis (issue with Imagemagick)
@@ -15,26 +15,28 @@ def test_duration():
        return
 
     clip = TextClip('hello world', size=(1280,720), color='white')
-    clip.set_duration(5)
+    clip = clip.set_duration(5) #  Changed due to #598.
     assert clip.duration == 5
+    clip.close()
 
     clip2 = clip.fx(blink, d_on=1, d_off=1)
-    clip2.set_duration(5)
+    clip2 = clip2.set_duration(5)
     assert clip2.duration == 5
+    clip2.close()
 
 # Moved from tests.py. Maybe we can remove these?
 def test_if_textclip_crashes_in_caption_mode():
     if TRAVIS:
        return
 
     TextClip(txt='foo', color='white', size=(640, 480), method='caption',
-             align='center', fontsize=25)
+             align='center', fontsize=25).close()
 
 def test_if_textclip_crashes_in_label_mode():
     if TRAVIS:
        return
 
-    TextClip(txt='foo', method='label')
+    TextClip(txt='foo', method='label').close()
 
 if __name__ == '__main__':
    pytest.main()