Don't fail because sys.path has duplicate entries. Fixes #337

2 files changed, 49 insertions, 7 deletions

diff --git a/tests/test_execfile.py b/tests/test_execfile.py
index 63fb919d..bf6d323f 100644
--- a/tests/test_execfile.py
+++ b/tests/test_execfile.py
@@ -1,6 +1,6 @@
 """Tests for coverage.execfile"""
 
-import compileall, os, re, sys
+import compileall, json, os, re, sys
 
 from coverage.backward import binary_bytes
 from coverage.execfile import run_python_file, run_python_module
@@ -16,7 +16,7 @@ class RunFileTest(CoverageTest):
     def test_run_python_file(self):
         tryfile = os.path.join(here, "try_execfile.py")
         run_python_file(tryfile, [tryfile, "arg1", "arg2"])
-        mod_globs = eval(self.stdout())             # pylint: disable=eval-used
+        mod_globs = json.loads(self.stdout())
 
         # The file should think it is __main__
         self.assertEqual(mod_globs['__name__'], "__main__")
@@ -26,7 +26,7 @@ class RunFileTest(CoverageTest):
         self.assertEqual(dunder_file, "try_execfile.py")
 
         # It should have its correct module data.
-        self.assertEqual(mod_globs['__doc__'],
+        self.assertEqual(mod_globs['__doc__'].splitlines()[0],
                             "Test file for run_python_file.")
         self.assertEqual(mod_globs['DATA'], "xyzzy")
         self.assertEqual(mod_globs['FN_VAL'], "my_fn('fooey')")
diff --git a/tests/try_execfile.py b/tests/try_execfile.py
index 825fdb70..1035dff9 100644
--- a/tests/try_execfile.py
+++ b/tests/try_execfile.py
@@ -1,6 +1,48 @@
-"""Test file for run_python_file."""
+"""Test file for run_python_file.
 
-import os, pprint, sys
+This file is executed two ways::
+
+    $ coverage run try_execfile.py
+
+and::
+
+    $ python try_execfile.py
+
+The output is compared to see that the program execution context is the same
+under coverage and under Python.
+
+It is not crucial that the execution be identical, there are some differences
+that are OK.  This program canonicalizes the output to gloss over those
+differences and get a clean diff.
+
+"""
+
+import json, os, sys
+
+# sys.path varies by execution environments.  Coverage.py uses setuptools to
+# make console scripts, which means pkg_resources is imported.  pkg_resources
+# removes duplicate entries from sys.path.  So we do that too, since the extra
+# entries don't affect the running of the program.
+
+def same_file(p1, p2):
+    """Determine if `p1` and `p2` refer to the same existing file."""
+    if not p1:
+        return not p2
+    if not os.path.exists(p1):
+        return False
+    if not os.path.exists(p2):
+        return False
+    return os.path.samefile(p1, p2)
+
+def without_same_files(filenames):
+    """Return the list `filenames` with duplicates (by same_file) removed."""
+    reduced = []
+    for filename in filenames:
+        if not any(same_file(filename, other) for other in reduced):
+            reduced.append(filename)
+    return reduced
+
+cleaned_sys_path = [os.path.normcase(p) for p in without_same_files(sys.path)]
 
 DATA = "xyzzy"
 
@@ -23,7 +65,7 @@ globals_to_check = {
     'FN_VAL': FN_VAL,
     '__main__.DATA': getattr(__main__, "DATA", "nothing"),
     'argv': sys.argv,
-    'path': [os.path.normcase(p) for p in sys.path],
+    'path': cleaned_sys_path,
 }
 
-pprint.pprint(globals_to_check)
+print(json.dumps(globals_to_check))