os.environ-related cleanups.

- Ensure that environment variables set to empty values behave as if
  unset (hence replacing `os.environ.get(foo, bar)` by
  `os.environ.get(foo) or bar`).
- Misc. additional cleanups.

Author: anntzer

lib/matplotlib/font_manager.py

@@ -147,8 +147,8 @@
     # common application, not really useful
     "/usr/lib/openoffice/share/fonts/truetype/",
     # user fonts
-    str(Path(os.environ.get('XDG_DATA_HOME',
-                            Path.home() / ".local/share")) / "fonts"),
+    str((Path(os.environ.get('XDG_DATA_HOME') or Path.home() / ".local/share"))
+        / "fonts"),
     str(Path.home() / ".fonts"),
 ]
 OSXFontDirectories = [

lib/matplotlib/tests/test_backend_bases.py

@@ -8,7 +8,6 @@
 import matplotlib.pyplot as plt
 import matplotlib.transforms as transforms
 import matplotlib.path as path
-import os
 import numpy as np
 import pytest
 
@@ -75,7 +74,7 @@ def test_canvas_change():
 def test_non_gui_warning(monkeypatch):
     plt.subplots()
 
-    monkeypatch.setitem(os.environ, "DISPLAY", ":999")
+    monkeypatch.setenv("DISPLAY", ":999")
 
     with pytest.warns(UserWarning) as rec:
         plt.show()

lib/matplotlib/tests/test_backend_pgf.py

@@ -122,7 +122,7 @@ def test_xelatex():
 @pytest.mark.backend('pgf')
 @image_comparison(['pgf_pdflatex.pdf'], style='default')
 def test_pdflatex():
-    if os.environ.get('APPVEYOR', False):
+    if os.environ.get('APPVEYOR'):
         pytest.xfail("pdflatex test does not work on appveyor due to missing "
                      "LaTeX fonts")
 

lib/matplotlib/tests/test_font_manager.py

@@ -170,8 +170,7 @@ def test_user_fonts_linux(tmpdir, monkeypatch):
 
 @pytest.mark.skipif(sys.platform != 'win32', reason='Windows only')
 def test_user_fonts_win32():
-    if not (os.environ.get('APPVEYOR', False) or
-            os.environ.get('TF_BUILD', False)):
+    if not (os.environ.get('APPVEYOR') or os.environ.get('TF_BUILD')):
         pytest.xfail("This test should only run on CI (appveyor or azure) "
                      "as the developer's font directory should remain "
                      "unchanged.")

setupext.py

@@ -179,7 +179,7 @@ def get_and_extract_tarball(urls, sha, dirname):
 
 
 # matplotlib build options, which can be altered using setup.cfg
-setup_cfg = os.environ.get('MPLSETUPCFG', 'setup.cfg')
+setup_cfg = os.environ.get('MPLSETUPCFG') or 'setup.cfg'
 config = configparser.ConfigParser()
 if os.path.exists(setup_cfg):
     config.read(setup_cfg)
@@ -213,7 +213,7 @@ def get_pkg_config():
     """
     if sys.platform == 'win32':
         return None
-    pkg_config = os.environ.get('PKG_CONFIG', 'pkg-config')
+    pkg_config = os.environ.get('PKG_CONFIG') or 'pkg-config'
     if shutil.which(pkg_config) is None:
         print(
             "IMPORTANT WARNING:\n"