Fix passing both window command and environment

src/libtmux/server.py

@@ -499,9 +499,6 @@ def new_session(
         if y is not None:
             tmux_args += ("-y", y)
 
-        if window_command:
-            tmux_args += (window_command,)
-
         if environment:
             if has_gte_version("3.2"):
                 for k, v in environment.items():
@@ -511,6 +508,9 @@ def new_session(
                     "Environment flag ignored, tmux 3.2 or newer required.",
                 )
 
+        if window_command:
+            tmux_args += (window_command,)
+
         proc = self.cmd("new-session", *tmux_args)
 
         if proc.stderr:

tests/test_server.py

@@ -1,7 +1,9 @@
 """Test for libtmux Server object."""
 
 import logging
+import os
 import subprocess
+import time
 
 import pytest
 
@@ -131,6 +133,28 @@ def test_new_session_shell(server: Server) -> None:
         assert pane_start_command == cmd
 
 
+def test_new_session_shell_env(server: Server) -> None:
+    """Verify ``Server.new_session`` creates valid session running w/ command."""
+    cmd = "sleep 1m"
+    env = dict(os.environ)
+    mysession = server.new_session(
+        "test_new_session_env", window_command=cmd, environment=env
+    )
+    time.sleep(0.1)
+    window = mysession.windows[0]
+    pane = window.panes[0]
+    assert mysession.session_name == "test_new_session_env"
+    assert server.has_session("test_new_session_env")
+
+    pane_start_command = pane.pane_start_command
+    assert pane_start_command is not None
+
+    if has_gte_version("3.2"):
+        assert pane_start_command.replace('"', "") == cmd
+    else:
+        assert pane_start_command == cmd
+
+
 @pytest.mark.skipif(has_version("3.2"), reason="Wrong width returned with 3.2")
 def test_new_session_width_height(server: Server) -> None:
     """Verify ``Server.new_session`` creates valid session running w/ dimensions."""