feat(Window.split_window): set up environment

This allows to set up a custom environment when creating a new pane.

Author: zappolowski

src/libtmux/window.py

@@ -442,6 +442,7 @@ def split_window(
         vertical: bool = True,
         shell: t.Optional[str] = None,
         percent: t.Optional[int] = None,
+        environment: t.Optional[t.Dict[str, str]] = None,
     ) -> Pane:
         """
         Split window and return the created :class:`Pane`.
@@ -520,6 +521,10 @@ def split_window(
         if not attach:
             tmux_args += ("-d",)
 
+        if environment:
+            for k, v in environment.items():
+                tmux_args += ("-e%s=%s" % (k, v),)
+
         if shell:
             tmux_args += (shell,)
 

tests/test_window.py

@@ -1,5 +1,6 @@
 """Test for libtmux Window object."""
 import logging
+import time
 import typing as t
 
 import pytest
@@ -310,3 +311,16 @@ def test_empty_window_name(session: Session) -> None:
         "#{==:#{session_name}," + session.name + "}",
     )
     assert "''" in cmd.stdout
+
+
+def test_split_window_with_environment(session: Session) -> None:
+    window = session.new_window(window_name="split_window_with_environment")
+    pane = window.split_window(
+        shell="/usr/bin/env PS1='$ ' bash --norc --noprofile",
+        environment={"ENV_VAR": "pane"},
+    )
+    assert pane is not None
+    # wait a bit for the prompt to be ready as the test gets flaky otherwise
+    time.sleep(0.05)
+    pane.send_keys("echo $ENV_VAR")
+    assert pane.capture_pane() == ["$ echo $ENV_VAR", "pane", "$"]