TST: Remove superfluous chdir from tests

These tests don't chdir back to the original directory on exit, so
anything using the current directory would be in the temporary directory
of this test.

Most notably, any image comparison results would be dumped in that
temporary directory instead of the usual `result_images` in the current
directory.

Author: QuLogic

lib/matplotlib/tests/test_backend_pdf.py

@@ -81,43 +81,47 @@ def test_multipage_properfinalize():
 
 
 def test_multipage_keep_empty(tmp_path):
-    os.chdir(tmp_path)
-
     # test empty pdf files
 
     # an empty pdf is left behind with keep_empty unset
-    with pytest.warns(mpl.MatplotlibDeprecationWarning), PdfPages("a.pdf") as pdf:
+    fn = tmp_path / "a.pdf"
+    with pytest.warns(mpl.MatplotlibDeprecationWarning), PdfPages(fn) as pdf:
         pass
-    assert os.path.exists("a.pdf")
+    assert fn.exists()
 
     # an empty pdf is left behind with keep_empty=True
+    fn = tmp_path / "b.pdf"
     with pytest.warns(mpl.MatplotlibDeprecationWarning), \
-            PdfPages("b.pdf", keep_empty=True) as pdf:
+            PdfPages(fn, keep_empty=True) as pdf:
         pass
-    assert os.path.exists("b.pdf")
+    assert fn.exists()
 
     # an empty pdf deletes itself afterwards with keep_empty=False
-    with PdfPages("c.pdf", keep_empty=False) as pdf:
+    fn = tmp_path / "c.pdf"
+    with PdfPages(fn, keep_empty=False) as pdf:
         pass
-    assert not os.path.exists("c.pdf")
+    assert not fn.exists()
 
     # test pdf files with content, they should never be deleted
 
     # a non-empty pdf is left behind with keep_empty unset
-    with PdfPages("d.pdf") as pdf:
+    fn = tmp_path / "d.pdf"
+    with PdfPages(fn) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("d.pdf")
+    assert fn.exists()
 
     # a non-empty pdf is left behind with keep_empty=True
+    fn = tmp_path / "e.pdf"
     with pytest.warns(mpl.MatplotlibDeprecationWarning), \
-            PdfPages("e.pdf", keep_empty=True) as pdf:
+            PdfPages(fn, keep_empty=True) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("e.pdf")
+    assert fn.exists()
 
     # a non-empty pdf is left behind with keep_empty=False
-    with PdfPages("f.pdf", keep_empty=False) as pdf:
+    fn = tmp_path / "f.pdf"
+    with PdfPages(fn, keep_empty=False) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("f.pdf")
+    assert fn.exists()
 
 
 def test_composite_image():

lib/matplotlib/tests/test_backend_pgf.py

@@ -288,43 +288,47 @@ def test_pdf_pages_metadata_check(monkeypatch, system):
 
 @needs_pgf_xelatex
 def test_multipage_keep_empty(tmp_path):
-    os.chdir(tmp_path)
-
     # test empty pdf files
 
     # an empty pdf is left behind with keep_empty unset
-    with pytest.warns(mpl.MatplotlibDeprecationWarning), PdfPages("a.pdf") as pdf:
+    fn = tmp_path / "a.pdf"
+    with pytest.warns(mpl.MatplotlibDeprecationWarning), PdfPages(fn) as pdf:
         pass
-    assert os.path.exists("a.pdf")
+    assert fn.exists()
 
     # an empty pdf is left behind with keep_empty=True
+    fn = tmp_path / "b.pdf"
     with pytest.warns(mpl.MatplotlibDeprecationWarning), \
-            PdfPages("b.pdf", keep_empty=True) as pdf:
+            PdfPages(fn, keep_empty=True) as pdf:
         pass
-    assert os.path.exists("b.pdf")
+    assert fn.exists()
 
     # an empty pdf deletes itself afterwards with keep_empty=False
-    with PdfPages("c.pdf", keep_empty=False) as pdf:
+    fn = tmp_path / "c.pdf"
+    with PdfPages(fn, keep_empty=False) as pdf:
         pass
-    assert not os.path.exists("c.pdf")
+    assert not fn.exists()
 
     # test pdf files with content, they should never be deleted
 
     # a non-empty pdf is left behind with keep_empty unset
-    with PdfPages("d.pdf") as pdf:
+    fn = tmp_path / "d.pdf"
+    with PdfPages(fn) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("d.pdf")
+    assert fn.exists()
 
     # a non-empty pdf is left behind with keep_empty=True
+    fn = tmp_path / "e.pdf"
     with pytest.warns(mpl.MatplotlibDeprecationWarning), \
-            PdfPages("e.pdf", keep_empty=True) as pdf:
+            PdfPages(fn, keep_empty=True) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("e.pdf")
+    assert fn.exists()
 
     # a non-empty pdf is left behind with keep_empty=False
-    with PdfPages("f.pdf", keep_empty=False) as pdf:
+    fn = tmp_path / "f.pdf"
+    with PdfPages(fn, keep_empty=False) as pdf:
         pdf.savefig(plt.figure())
-    assert os.path.exists("f.pdf")
+    assert fn.exists()
 
 
 @needs_pgf_xelatex