fix: set sys.path correctly when running through a symlink. #2157

nedbat · nedbat · commit f4413c6c0f19 · 2026-04-17T08:36:58.000-04:00
diff --git a/CHANGES.rst b/CHANGES.rst
@@ -23,9 +23,13 @@ upgrading your version of coverage.py.
 Unreleased
 ----------
 
+- Fix: running a Python file through a symlink now sets the sys.path correctly,
+  matching regular Python behavior. Fixes `issue 2157`_.
+
 - We are no longer testing eventlet support. Eventlet issues stern deprecation
   warnings that break our tests. Our support code is still there.
 
+.. _issue 2157: https://github.com/coveragepy/coveragepy/issues/2157
 
 .. start-releases
 
diff --git a/coverage/execfile.py b/coverage/execfile.py
@@ -101,7 +101,7 @@ def prepare(self) -> None:
             # directory.
             path0 = self.arg0
         else:
-            path0 = os.path.abspath(os.path.dirname(self.arg0))
+            path0 = os.path.abspath(os.path.dirname(os.path.realpath(self.arg0)))
 
         if os.path.isdir(sys.path[0]):
             # sys.path fakery.  If we are being run as a command, then sys.path[0]
diff --git a/tests/test_process.py b/tests/test_process.py
@@ -969,6 +969,16 @@ def test_coverage_zip_is_like_python(self) -> None:
         actual = self.run_command(f"python {cov_main} run run_me.py")
         self.assert_tryexecfile_output(expected, actual)
 
+    @pytest.mark.skipif(env.WINDOWS, reason="Windows can't make symlinks")
+    def test_coverage_in_symlink_is_like_python(self) -> None:
+        # https://github.com/coveragepy/coveragepy/issues/2157
+        self.make_file("real/run_me.py", TRY_EXECFILE_CODE)
+        os.mkdir("link")
+        os.symlink("../real/run_me.py", "link/run_me.py")
+        expected = self.run_command("python link/run_me.py")
+        actual = self.run_command("coverage run link/run_me.py")
+        self.assert_tryexecfile_output(expected, actual)
+
     @pytest.mark.skipif(env.PYVERSION < (3, 11), reason="PYTHONSAFEPATH is new in 3.11")
     @pytest.mark.skipif(
         env.WINDOWS,
