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better error handling when xvfb is not installed

master
Corey Goldberg 6 years ago
parent
commit
db65ebdf8d
  1. 24
      xvfbwrapper.py

24
xvfbwrapper.py

@ -1,9 +1,8 @@
#!/usr/bin/env python
#
# * Corey Goldberg, 2012, 2013, 2015
# * Corey Goldberg, 2012, 2013, 2016
#
# * inspired by:
# PyVirtualDisplay: http://pypi.python.org/pypi/PyVirtualDisplay
# * inspired by: PyVirtualDisplay
"""wrapper for running display inside X virtual framebuffer (Xvfb)"""
@ -23,6 +22,10 @@ class Xvfb:
self.height = height
self.colordepth = colordepth
if not self._xvfb_exists():
msg = 'Can not find Xvfb. Please install it and try again.'
raise EnvironmentError(msg)
self.xvfb_cmd = [
'-screen', '0', '%dx%dx%d' %
(self.width, self.height, self.colordepth)
@ -31,12 +34,13 @@ class Xvfb:
for key, value in kwargs.items():
self.xvfb_cmd = self.xvfb_cmd + ['-%s' % key, value]
self.proc = None
if 'DISPLAY' in os.environ:
self.old_display_num = os.environ['DISPLAY'].split(':')[1]
else:
self.old_display_num = 0
self.proc = None
def __enter__(self):
self.start()
return self
@ -47,6 +51,7 @@ class Xvfb:
def start(self):
self.vdisplay_num = self.search_for_free_display()
self.xvfb_cmd = ['Xvfb', ':%d' % self.vdisplay_num] + self.xvfb_cmd
with open(os.devnull, 'w') as fnull:
self.proc = subprocess.Popen(self.xvfb_cmd,
stdout=fnull,
@ -59,7 +64,7 @@ class Xvfb:
else:
self._redirect_display(self.old_display_num)
self.proc = None
print('Error: Xvfb did not start')
raise RuntimeError('Xvfb did not start')
def stop(self):
self._redirect_display(self.old_display_num)
@ -76,7 +81,7 @@ class Xvfb:
else:
display_num = min_display_num
random.seed()
display_num += random.randint(0, 100)
display_num += random.randint(0, 1000)
return display_num
def _lock_files(self):
@ -89,3 +94,10 @@ class Xvfb:
def _redirect_display(self, display_num):
os.environ['DISPLAY'] = ':%s' % display_num
def _xvfb_exists(self):
"""Check that Xvfb exists in PATH and is executable."""
return any(
os.access(os.path.join(path, 'Xvfb'), os.X_OK)
for path in os.environ['PATH'].split(os.pathsep)
)
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