terminalprogress: disable when TERM=dumb

TERM=dumb shouldn't emit escape codes like terminalprogress does, it
would likely come out as literal escape characters.

Author: bluetech

changelog/13896.bugfix.rst

@@ -1,3 +1,5 @@
 The terminal progress feature added in pytest 9.0.0 has been disabled by default, except on Windows, due to compatibility issues with some terminal emulators.
 
 You may enable it again by passing ``-p terminalprogress``. We may enable it by default again once compatibility improves in the future.
+
+Additionally, when the environment variable ``TERM`` is ``dumb``, the escape codes are no longer emitted, even if the plugin is enabled.

src/_pytest/terminalprogress.py

@@ -11,6 +11,8 @@
 
 from __future__ import annotations
 
+import os
+
 from _pytest.config import Config
 from _pytest.config import hookimpl
 from _pytest.terminal import TerminalProgressPlugin
@@ -23,6 +25,6 @@ def pytest_configure(config: Config) -> None:
         "terminalreporter"
     )
 
-    if reporter is not None and reporter.isatty():
+    if reporter is not None and reporter.isatty() and os.environ.get("TERM") != "dumb":
         plugin = TerminalProgressPlugin(reporter)
         config.pluginmanager.register(plugin, name="terminalprogress-plugin")

testing/test_terminal.py

@@ -3460,6 +3460,16 @@ def test_disabled_for_non_tty(
         plugin = config.pluginmanager.get_plugin("terminalprogress-plugin")
         assert plugin is None
 
+    def test_disabled_for_dumb_terminal(
+        self, pytester: pytest.Pytester, monkeypatch: MonkeyPatch
+    ) -> None:
+        """Test that plugin is disabled when TERM=dumb."""
+        monkeypatch.setenv("TERM", "dumb")
+        monkeypatch.setattr(sys.stdout, "isatty", lambda: True)
+        config = pytester.parseconfigure("-p", "terminalprogress")
+        plugin = config.pluginmanager.get_plugin("terminalprogress-plugin")
+        assert plugin is None
+
     @pytest.mark.parametrize(
         ["state", "progress", "expected"],
         [