test: add direct unit tests for _start_input_reader_thread (#1056)

tests/copilot_usage/test_cli.py

@@ -9,6 +9,7 @@
 import re
 import threading
 import time
+from collections.abc import Iterator
 from datetime import UTC, datetime, timedelta, timezone
 from pathlib import Path
 from typing import Any
@@ -22,13 +23,15 @@
 
 from copilot_usage import __version__
 from copilot_usage.cli import (
+    _FALLBACK_EOF,
     _build_session_index,
     _DateTimeOrDate,
     _normalize_until,
     _ParsedDateArg,
     _print_version_header,
     _read_line_nonblocking,
     _show_session_by_index,
+    _start_input_reader_thread,
     _start_observer,
     _stop_observer,
     _validate_since_until,
@@ -2169,6 +2172,89 @@ def test_returns_stripped_line(self) -> None:
             os.close(w_fd)
 
 
+# ---------------------------------------------------------------------------
+# _start_input_reader_thread unit tests (issue #1056)
+# ---------------------------------------------------------------------------
+
+
+class TestStartInputReaderThread:
+    """Direct unit tests for _start_input_reader_thread."""
+
+    def test_thread_is_daemon(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Spawned thread must be daemon so it cannot block process exit."""
+        captured_daemon: list[bool | None] = []
+        _real_thread = threading.Thread
+
+        def _spy_thread(*args: Any, **kwargs: Any) -> threading.Thread:
+            captured_daemon.append(kwargs.get("daemon"))
+            return _real_thread(*args, **kwargs)
+
+        monkeypatch.setattr("copilot_usage.cli.threading.Thread", _spy_thread)
+        monkeypatch.setattr("builtins.input", lambda: (_ for _ in ()).throw(EOFError()))
+
+        q = _start_input_reader_thread()
+        q.get(timeout=2.0)  # drain sentinel so thread exits
+
+        assert captured_daemon == [True], "input-fallback thread must be daemon=True"
+
+    def test_normal_input_is_stripped_and_queued(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
+        """User input is stripped before being placed on the queue."""
+        inputs: Iterator[str | BaseException] = iter(["  hello  ", EOFError()])
+
+        def _fake_input() -> str:
+            val = next(inputs)
+            if isinstance(val, BaseException):
+                raise val
+            return val
+
+        monkeypatch.setattr("builtins.input", _fake_input)
+
+        q = _start_input_reader_thread()
+        assert q.get(timeout=2.0) == "hello"
+        assert q.get(timeout=2.0) == _FALLBACK_EOF
+
+    def test_eoferror_puts_fallback_sentinel(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
+        """EOFError from input() places _FALLBACK_EOF on the queue."""
+        monkeypatch.setattr("builtins.input", lambda: (_ for _ in ()).throw(EOFError()))
+
+        q = _start_input_reader_thread()
+        assert q.get(timeout=2.0) == _FALLBACK_EOF
+
+    def test_keyboard_interrupt_puts_fallback_sentinel(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
+        """KeyboardInterrupt from input() places _FALLBACK_EOF on the queue."""
+        monkeypatch.setattr(
+            "builtins.input", lambda: (_ for _ in ()).throw(KeyboardInterrupt())
+        )
+
+        q = _start_input_reader_thread()
+        assert q.get(timeout=2.0) == _FALLBACK_EOF
+
+    def test_unexpected_exception_puts_fallback_and_logs_warning(
+        self, monkeypatch: pytest.MonkeyPatch
+    ) -> None:
+        """Unexpected exception places _FALLBACK_EOF and logs a warning."""
+        monkeypatch.setattr(
+            "builtins.input", lambda: (_ for _ in ()).throw(RuntimeError("boom"))
+        )
+
+        import copilot_usage.cli as cli_mod
+
+        with patch.object(cli_mod.logger, "warning") as warn_spy:
+            q = _start_input_reader_thread()
+            sentinel = q.get(timeout=2.0)
+
+        assert sentinel == _FALLBACK_EOF
+        warn_spy.assert_called_once()
+        assert warn_spy.call_args is not None
+        assert "Unexpected stdin error" in warn_spy.call_args.args[0]
+
+
 # ---------------------------------------------------------------------------
 # Gap 3 — _interactive_loop stdin fallback (issue #258)
 # ---------------------------------------------------------------------------