fix(server): robust output parsing and env var safety

why:
- parse_output used strict=False which could silently hide truncated output
- TMUX env var modification was not exception-safe
- new test didn't verify all populated fields

what:
- Update parse_output to use strict=True after handling trailing separator
- Wrap TMUX env var restoration in try/finally block
- Add assertions for window_id and pane_id in new session test

Author: tony

src/libtmux/neo.py

@@ -233,7 +233,13 @@ def parse_output(output: str) -> OutputRaw:
     False
     """
     formats, _ = get_output_format()
-    formatter = dict(zip(formats, output.split(FORMAT_SEPARATOR), strict=False))
+    values = output.split(FORMAT_SEPARATOR)
+
+    # Remove the trailing empty string from the split
+    if values and values[-1] == "":
+        values = values[:-1]
+
+    formatter = dict(zip(formats, values, strict=True))
     return {k: v for k, v in formatter.items() if v}
 
 

src/libtmux/server.py

@@ -539,48 +539,50 @@ def new_session(
         if env:
             del os.environ["TMUX"]
 
-        _fields, format_string = get_output_format()
+        try:
+            _fields, format_string = get_output_format()
 
-        tmux_args: tuple[str | int, ...] = (
-            "-P",
-            f"-F{format_string}",
-        )
+            tmux_args: tuple[str | int, ...] = (
+                "-P",
+                f"-F{format_string}",
+            )
 
-        if session_name is not None:
-            tmux_args += (f"-s{session_name}",)
+            if session_name is not None:
+                tmux_args += (f"-s{session_name}",)
 
-        if not attach:
-            tmux_args += ("-d",)
+            if not attach:
+                tmux_args += ("-d",)
 
-        if start_directory:
-            start_directory = pathlib.Path(start_directory).expanduser()
-            tmux_args += ("-c", str(start_directory))
+            if start_directory:
+                start_directory = pathlib.Path(start_directory).expanduser()
+                tmux_args += ("-c", str(start_directory))
 
-        if window_name:
-            tmux_args += ("-n", window_name)
+            if window_name:
+                tmux_args += ("-n", window_name)
 
-        if x is not None:
-            tmux_args += ("-x", x)
+            if x is not None:
+                tmux_args += ("-x", x)
 
-        if y is not None:
-            tmux_args += ("-y", y)
+            if y is not None:
+                tmux_args += ("-y", y)
 
-        if environment:
-            for k, v in environment.items():
-                tmux_args += (f"-e{k}={v}",)
+            if environment:
+                for k, v in environment.items():
+                    tmux_args += (f"-e{k}={v}",)
 
-        if window_command:
-            tmux_args += (window_command,)
+            if window_command:
+                tmux_args += (window_command,)
 
-        proc = self.cmd("new-session", *tmux_args)
+            proc = self.cmd("new-session", *tmux_args)
 
-        if proc.stderr:
-            raise exc.LibTmuxException(proc.stderr)
+            if proc.stderr:
+                raise exc.LibTmuxException(proc.stderr)
 
-        session_stdout = proc.stdout[0]
+            session_stdout = proc.stdout[0]
 
-        if env:
-            os.environ["TMUX"] = env
+        finally:
+            if env:
+                os.environ["TMUX"] = env
 
         session_data = parse_output(session_stdout)
 

tests/test_server.py

@@ -109,6 +109,8 @@ def test_new_session_returns_populated_session(server: Server) -> None:
     session = server.new_session(session_name="test_populated")
     assert session.session_id is not None
     assert session.session_name == "test_populated"
+    assert session.window_id is not None
+    assert session.pane_id is not None
 
 
 def test_new_session_no_name(server: Server) -> None: