work-2u3nd.1: filed findings

src/flight_cli/_watch.py

@@ -171,10 +171,16 @@ def _locked() -> Generator[None]:
         os.close(fd)
 
 
+# The currency and the exception name are remote text, and a reader of stdout takes
+# each line as one watch, so the newline CTRL keeps would split a record in two. A
+# failure line is one record too: the store path comes from the environment.
+_ONE_LINE: Final = {**CTRL, ord("\n"): " "}
+
+
 def _fail(message: str, code: int) -> typer.Exit:
     """The store path comes from the environment and a key in an unusable store
     from the file, so either can carry characters a terminal acts on."""
-    typer.echo(message.translate(CTRL), err=True)
+    typer.echo(message.translate(_ONE_LINE), err=True)
     return typer.Exit(code)
 
 
@@ -314,11 +320,6 @@ def _poll(w: Watch, last: _Seen | None) -> tuple[str, _Seen | None]:
     return f"{head}: lowest {amount} on {day}{verdict}{change}", fare
 
 
-# The currency and the exception name are remote text, and a reader of stdout takes
-# each line as one watch, so the newline CTRL keeps would split a record in two.
-_ONE_LINE: Final = {**CTRL, ord("\n"): " "}
-
-
 @watch_app.command("run")
 def watch_run() -> None:
     """Price each saved watch once and print a line each, with the change since the last

tests/test_watch_config_path_newline.py

@@ -0,0 +1,28 @@
+"""`flight watch add` names a config path that carries a newline on one stderr line."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from typer.testing import CliRunner
+
+from flight_cli import cli
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    import pytest
+
+
+def test_a_config_path_with_a_newline_is_named_on_one_line(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    directory = tmp_path / "h" / "line1\nline2"
+    assert directory.is_relative_to(tmp_path)
+    directory.parent.mkdir()
+    _ = directory.write_text("not a directory")
+    monkeypatch.setenv("FLIGHT_CLI_CONFIG_DIR", str(directory))
+    result = CliRunner().invoke(cli.app, ["watch", "add", "JFK", "LHR"])
+    assert (result.exit_code, type(result.exception).__name__) == (1, "SystemExit"), result.output
+    named = str(directory).replace("\n", " ")
+    assert result.output.splitlines() == [f"{named} cannot be created: File exists"]