tests: re-harden test_cmdline_python_package_symlink

testing/acceptance_test.py

@@ -762,21 +762,13 @@ def test():
         result = testdir.runpytest(str(p) + "::test", "--doctest-modules")
         result.stdout.fnmatch_lines(["*1 passed*"])
 
-    def test_cmdline_python_package_symlink(self, testdir, monkeypatch):
+    def test_cmdline_python_package_symlink(
+        self, testdir, monkeypatch, symlink_or_skip
+    ):
         """
         test --pyargs option with packages with path containing symlink can
         have conftest.py in their package (#2985)
         """
-        # dummy check that we can actually create symlinks: on Windows `os.symlink` is available,
-        # but normal users require special admin privileges to create symlinks.
-        if sys.platform == "win32":
-            try:
-                os.symlink(
-                    str(testdir.tmpdir.ensure("tmpfile")),
-                    str(testdir.tmpdir.join("tmpfile2")),
-                )
-            except OSError as e:
-                pytest.skip(str(e.args[0]))
         monkeypatch.delenv("PYTHONDONTWRITEBYTECODE", raising=False)
 
         dirname = "lib"
@@ -794,7 +786,11 @@ def test_cmdline_python_package_symlink(self, testdir, monkeypatch):
 
         d_local = testdir.mkdir("local")
         symlink_location = os.path.join(str(d_local), "lib")
-        os.symlink(str(d), symlink_location, target_is_directory=True)
+        try:
+            symlink_or_skip(str(d), symlink_location, target_is_directory=True)
+            has_symlinks = True
+        except pytest.skip.Exception:
+            has_symlinks = False
 
         # The structure of the test directory is now:
         # .
@@ -816,22 +812,21 @@ def test_cmdline_python_package_symlink(self, testdir, monkeypatch):
 
         # module picked up in symlink-ed directory:
         # It picks up local/lib/foo/bar (symlink) via sys.path.
-        result = testdir.runpytest("--pyargs", "-v", "foo.bar")
-        testdir.chdir()
+        result = testdir.runpytest("--pyargs", "-vv", "foo.bar")
         assert result.ret == 0
-        if hasattr(py.path.local, "mksymlinkto"):
+        if has_symlinks:
             result.stdout.fnmatch_lines(
                 [
-                    "lib/foo/bar/test_bar.py::test_bar PASSED*",
-                    "lib/foo/bar/test_bar.py::test_other PASSED*",
+                    "lib/foo/bar/test_bar.py::test_bar <- local/lib/foo/bar/test_bar.py PASSED*",
+                    "lib/foo/bar/test_bar.py::test_other <- local/lib/foo/bar/test_bar.py PASSED*",
                     "*2 passed*",
                 ]
             )
         else:
             result.stdout.fnmatch_lines(
                 [
-                    "*lib/foo/bar/test_bar.py::test_bar PASSED*",
-                    "*lib/foo/bar/test_bar.py::test_other PASSED*",
+                    "local/lib/foo/bar/test_bar.py::test_bar PASSED*",
+                    "local/lib/foo/bar/test_bar.py::test_other PASSED*",
                     "*2 passed*",
                 ]
             )

testing/conftest.py

@@ -1,3 +1,4 @@
+import os
 import re
 import sys
 from typing import List
@@ -136,6 +137,24 @@ def testdir(testdir: Testdir) -> Testdir:
     return testdir
 
 
+@pytest.fixture
+def symlink_or_skip():
+    """Return a function that creates a symlink or raises ``Skip``.
+
+    On Windows `os.symlink` is available, but normal users require special
+    admin privileges to create symlinks.
+    """
+
+    def wrap_os_symlink(src, dst, *args, **kwargs):
+        try:
+            os.symlink(src, dst, *args, **kwargs)
+        except OSError as e:
+            pytest.skip("os.symlink({!r}) failed: {!r}".format((src, dst), e))
+        assert os.path.islink(dst)
+
+    return wrap_os_symlink
+
+
 @pytest.fixture(scope="session")
 def color_mapping():
     """Returns a utility class which can replace keys in strings in the form "{NAME}"