fix & test pushd instead of do_command

Author: maedoc

cmdstanpy/utils.py

@@ -1001,7 +1001,6 @@ def do_command(
 
     """
     get_logger().debug('cmd: %s\ncwd: %s', ' '.join(cmd), cwd)
-    restore_cwd = os.getcwd() if cwd is not None else None
     try:
         # NB: Using this rather than cwd arg to Popen due to windows behavior
         with pushd(cwd if cwd is not None else '.'):
@@ -1043,8 +1042,6 @@ def do_command(
                 raise RuntimeError(msg)
     except OSError as e:
         msg = 'Command: {}\nfailed with error {}\n'.format(cmd, str(e))
-        if restore_cwd is not None:
-            os.chdir(restore_cwd)
         raise RuntimeError(msg) from e
 
 
@@ -1322,8 +1319,10 @@ def pushd(new_dir: str) -> Iterator[None]:
     """Acts like pushd/popd."""
     previous_dir = os.getcwd()
     os.chdir(new_dir)
-    yield
-    os.chdir(previous_dir)
+    try:
+        yield
+    finally:
+        os.chdir(previous_dir)
 
 
 def report_signal(sig: int) -> None:

test/test_utils.py

@@ -45,6 +45,7 @@
     validate_dir,
     windows_short_path,
     write_stan_json,
+    pushd,
 )
 
 HERE = os.path.dirname(os.path.abspath(__file__))
@@ -806,17 +807,19 @@ def test_exit(self):
             with self.assertRaises(RuntimeError):
                 do_command(args, HERE)
 
+
+class PushdTest(unittest.TestCase):
+
     def test_restore_cwd(self):
         "Ensure do_command in a different cwd restores cwd after error."
-        before = os.getcwd()
-        # after = None
+        cwd = os.getcwd()
         try:
-            do_command(cmd=['ls /does-not-exist'], cwd=os.path.dirname(before))
+            with self.assertRaises(RuntimeError):
+                with pushd(os.path.dirname(cwd)):
+                    raise RuntimeError('error')
         except RuntimeError:
             pass
-        finally:
-            after = os.getcwd()
-        self.assertEqual(before, after)
+        self.assertEqual(cwd, os.getcwd())
 
 
 class FlattenTest(unittest.TestCase):