Merge pull request #13247 from Kojoley/tests-handle-no-matplotlib

Skip test_pylabtools when no matplotlib installed

IPython/core/tests/test_pylabtools.py

@@ -1,273 +1,274
 """Tests for pylab tools module.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 
 from binascii import a2b_base64
 from io import BytesIO
 
-import matplotlib
+import pytest
+
+matplotlib = pytest.importorskip("matplotlib")
 matplotlib.use('Agg')
 from matplotlib.figure import Figure
 
 from matplotlib import pyplot as plt
 from matplotlib_inline import backend_inline
 import numpy as np
-import pytest
 
 from IPython.core.getipython import get_ipython
 from IPython.core.interactiveshell import InteractiveShell
 from IPython.core.display import _PNG, _JPEG
 from .. import pylabtools as pt
 
 from IPython.testing import decorators as dec
 
 
 def test_figure_to_svg():
     # simple empty-figure test
     fig = plt.figure()
     assert pt.print_figure(fig, "svg") is None
 
     plt.close('all')
 
     # simple check for at least svg-looking output
     fig = plt.figure()
     ax = fig.add_subplot(1,1,1)
     ax.plot([1,2,3])
     plt.draw()
     svg = pt.print_figure(fig, "svg")[:100].lower()
     assert "doctype svg" in svg
 
 
 def _check_pil_jpeg_bytes():
     """Skip if PIL can't write JPEGs to BytesIO objects"""
     # PIL's JPEG plugin can't write to BytesIO objects
     # Pillow fixes this
     from PIL import Image
     buf = BytesIO()
     img = Image.new("RGB", (4,4))
     try:
         img.save(buf, 'jpeg')
     except Exception as e:
         ename = e.__class__.__name__
         raise pytest.skip("PIL can't write JPEG to BytesIO: %s: %s" % (ename, e)) from e
 
 @dec.skip_without("PIL.Image")
 def test_figure_to_jpeg():
     _check_pil_jpeg_bytes()
     # simple check for at least jpeg-looking output
     fig = plt.figure()
     ax = fig.add_subplot(1,1,1)
     ax.plot([1,2,3])
     plt.draw()
     jpeg = pt.print_figure(fig, 'jpeg', pil_kwargs={'optimize': 50})[:100].lower()
     assert jpeg.startswith(_JPEG)
 
 def test_retina_figure():
     # simple empty-figure test
     fig = plt.figure()
     assert pt.retina_figure(fig) == None
     plt.close('all')
 
     fig = plt.figure()
     ax = fig.add_subplot(1,1,1)
     ax.plot([1,2,3])
     plt.draw()
     png, md = pt.retina_figure(fig)
     assert png.startswith(_PNG)
     assert "width" in md
     assert "height" in md
 
 
 _fmt_mime_map = {
     'png': 'image/png',
     'jpeg': 'image/jpeg',
     'pdf': 'application/pdf',
     'retina': 'image/png',
     'svg': 'image/svg+xml',
 }
 
 def test_select_figure_formats_str():
     ip = get_ipython()
     for fmt, active_mime in _fmt_mime_map.items():
         pt.select_figure_formats(ip, fmt)
         for mime, f in ip.display_formatter.formatters.items():
             if mime == active_mime:
                 assert Figure in f
             else:
                 assert Figure not in f
 
 def test_select_figure_formats_kwargs():
     ip = get_ipython()
     kwargs = dict(quality=10, bbox_inches='tight')
     pt.select_figure_formats(ip, 'png', **kwargs)
     formatter = ip.display_formatter.formatters['image/png']
     f = formatter.lookup_by_type(Figure)
     cell = f.keywords
     expected = kwargs
     expected["base64"] = True
     expected["fmt"] = "png"
     assert cell == expected
 
     # check that the formatter doesn't raise
     fig = plt.figure()
     ax = fig.add_subplot(1,1,1)
     ax.plot([1,2,3])
     plt.draw()
     formatter.enabled = True
     png = formatter(fig)
     assert isinstance(png, str)
     png_bytes = a2b_base64(png)
     assert png_bytes.startswith(_PNG)
 
 def test_select_figure_formats_set():
     ip = get_ipython()
     for fmts in [
         {'png', 'svg'},
         ['png'],
         ('jpeg', 'pdf', 'retina'),
         {'svg'},
     ]:
         active_mimes = {_fmt_mime_map[fmt] for fmt in fmts}
         pt.select_figure_formats(ip, fmts)
         for mime, f in ip.display_formatter.formatters.items():
             if mime in active_mimes:
                 assert Figure in f
             else:
                 assert Figure not in f
 
 def test_select_figure_formats_bad():
     ip = get_ipython()
     with pytest.raises(ValueError):
         pt.select_figure_formats(ip, 'foo')
     with pytest.raises(ValueError):
         pt.select_figure_formats(ip, {'png', 'foo'})
     with pytest.raises(ValueError):
         pt.select_figure_formats(ip, ['retina', 'pdf', 'bar', 'bad'])
 
 def test_import_pylab():
     ns = {}
     pt.import_pylab(ns, import_all=False)
     assert "plt" in ns
     assert ns["np"] == np
 
 
 from traitlets.config import Config
 
 
 class TestPylabSwitch(object):
     class Shell(InteractiveShell):
         def init_history(self):
             """Sets up the command history, and starts regular autosaves."""
             self.config.HistoryManager.hist_file = ":memory:"
             super().init_history()
 
         def enable_gui(self, gui):
             pass
 
     def setup(self):
         import matplotlib
         def act_mpl(backend):
             matplotlib.rcParams['backend'] = backend
 
         # Save rcParams since they get modified
         self._saved_rcParams = matplotlib.rcParams
         self._saved_rcParamsOrig = matplotlib.rcParamsOrig
         matplotlib.rcParams = dict(backend='Qt4Agg')
         matplotlib.rcParamsOrig = dict(backend='Qt4Agg')
 
         # Mock out functions
         self._save_am = pt.activate_matplotlib
         pt.activate_matplotlib = act_mpl
         self._save_ip = pt.import_pylab
         pt.import_pylab = lambda *a,**kw:None
         self._save_cis = backend_inline.configure_inline_support
         backend_inline.configure_inline_support = lambda *a, **kw: None
 
     def teardown(self):
         pt.activate_matplotlib = self._save_am
         pt.import_pylab = self._save_ip
         backend_inline.configure_inline_support = self._save_cis
         import matplotlib
         matplotlib.rcParams = self._saved_rcParams
         matplotlib.rcParamsOrig = self._saved_rcParamsOrig
 
     def test_qt(self):
 
         s = self.Shell()
         gui, backend = s.enable_matplotlib(None)
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
         gui, backend = s.enable_matplotlib("inline")
         assert gui == "inline"
         assert s.pylab_gui_select == "qt"
 
         gui, backend = s.enable_matplotlib("qt")
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
         gui, backend = s.enable_matplotlib("inline")
         assert gui == "inline"
         assert s.pylab_gui_select == "qt"
 
         gui, backend = s.enable_matplotlib()
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
     def test_inline(self):
         s = self.Shell()
         gui, backend = s.enable_matplotlib("inline")
         assert gui == "inline"
         assert s.pylab_gui_select == None
 
         gui, backend = s.enable_matplotlib("inline")
         assert gui == "inline"
         assert s.pylab_gui_select == None
 
         gui, backend = s.enable_matplotlib("qt")
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
     def test_inline_twice(self):
         "Using '%matplotlib inline' twice should not reset formatters"
 
         ip = self.Shell()
         gui, backend = ip.enable_matplotlib("inline")
         assert gui == "inline"
 
         fmts =  {'png'}
         active_mimes = {_fmt_mime_map[fmt] for fmt in fmts}
         pt.select_figure_formats(ip, fmts)
 
         gui, backend = ip.enable_matplotlib("inline")
         assert gui == "inline"
 
         for mime, f in ip.display_formatter.formatters.items():
             if mime in active_mimes:
                 assert Figure in f
             else:
                 assert Figure not in f
 
     def test_qt_gtk(self):
         s = self.Shell()
         gui, backend = s.enable_matplotlib("qt")
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
         gui, backend = s.enable_matplotlib("gtk")
         assert gui == "qt"
         assert s.pylab_gui_select == "qt"
 
 
 def test_no_gui_backends():
     for k in ['agg', 'svg', 'pdf', 'ps']:
         assert k not in pt.backend2gui
 
 
 def test_figure_no_canvas():
     fig = Figure()
     fig.canvas = None
     pt.print_figure(fig)