1 files changed, 29 insertions, 13 deletions

diff --git a/tests/test_process.py b/tests/test_process.py
index dda43ba8..2e94c19a 100644
--- a/tests/test_process.py
+++ b/tests/test_process.py
@@ -11,6 +11,8 @@ import re
 import sys
 import textwrap
 
+import pytest
+
 import coverage
 from coverage import env, CoverageData
 from coverage.misc import output_encoding
@@ -692,6 +694,7 @@ class ProcessTest(CoverageTest):
         self.assertEqual(len(infos), 1)
         self.assertEqual(infos[0]['note'], u"These are musical notes: ♫𝅗𝅥♩")
 
+    @pytest.mark.expensive
     def test_fullcoverage(self):                        # pragma: not covered
         if env.PY2:             # This doesn't work on Python 2.
             self.skipTest("fullcoverage doesn't work on Python 2.")
@@ -1139,25 +1142,38 @@ def possible_pth_dirs():
     yield distutils.sysconfig.get_python_lib()
 
 
+def find_writable_pth_directory():
+    """Find a place to write a .pth file."""
+    for pth_dir in possible_pth_dirs():             # pragma: part covered
+        try_it = os.path.join(pth_dir, "touch_{0}.it".format(WORKER))
+        with open(try_it, "w") as f:
+            try:
+                f.write("foo")
+            except (IOError, OSError):              # pragma: not covered
+                continue
+
+        os.remove(try_it)
+        return pth_dir
+
+    return None
+
+WORKER = os.environ.get('PYTEST_XDIST_WORKER', '')
+PTH_DIR = find_writable_pth_directory()
+
+
 class ProcessCoverageMixin(object):
     """Set up a .pth file to coverage-measure all sub-processes."""
 
     def setUp(self):
         super(ProcessCoverageMixin, self).setUp()
-        # Find a place to put a .pth file.
+
+        # Create the .pth file.
+        self.assert_(PTH_DIR)
         pth_contents = "import coverage; coverage.process_startup()\n"
-        for pth_dir in possible_pth_dirs():             # pragma: part covered
-            worker = os.environ.get('PYTEST_XDIST_WORKER', '')
-            pth_path = os.path.join(pth_dir, "subcover_{0}.pth".format(worker))
-            with open(pth_path, "w") as pth:
-                try:
-                    pth.write(pth_contents)
-                    self.pth_path = pth_path
-                    break
-                except (IOError, OSError):              # pragma: not covered
-                    pass
-        else:                                           # pragma: not covered
-            raise Exception("Couldn't find a place for the .pth file")
+        pth_path = os.path.join(PTH_DIR, "subcover_{0}.pth".format(WORKER))
+        with open(pth_path, "w") as pth:
+            pth.write(pth_contents)
+            self.pth_path = pth_path
 
         self.addCleanup(os.remove, self.pth_path)