🐛 Fix TYPER_USE_RICH parsing to allow disabling Rich completely (#1539)

Co-authored-by: svlandeg <svlandeg@github.com>

Author: bckohan

tests/test_rich_markup_mode.py

@@ -1,3 +1,7 @@
+import os
+import subprocess
+import sys
+
 import pytest
 import typer
 import typer.completion
@@ -42,6 +46,43 @@ def main(arg: str):
     assert any(c in result.stdout for c in rounded)
 
 
+@pytest.mark.parametrize(
+    "env_var_value, expected_result",
+    [
+        ("1", True),
+        ("True", True),
+        ("TRUE", True),
+        ("true", True),
+        ("0", False),
+        ("False", False),
+        ("FALSE", False),
+        ("false", False),
+        ("somerandomvalue", True),
+    ],
+)
+def test_rich_markup_mode_envvar(env_var_value: str, expected_result: bool):
+    result = subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "coverage",
+            "run",
+            "-m",
+            "typer",
+            "tests/assets/cli/sample.py",
+            "--help",
+        ],
+        capture_output=True,
+        env={
+            **os.environ,
+            "TYPER_USE_RICH": env_var_value,
+            "PYTHONIOENCODING": "utf-8",
+        },
+        encoding="utf-8",
+    )
+    assert any(c in result.stdout for c in rounded) == expected_result
+
+
 @pytest.mark.parametrize(
     "mode,lines",
     [

typer/core.py

@@ -23,15 +23,16 @@
 import click.utils
 
 from ._typing import Literal
+from .utils import parse_boolean_env_var
 
 MarkupMode = Literal["markdown", "rich", None]
 MARKUP_MODE_KEY = "TYPER_RICH_MARKUP_MODE"
 
-HAS_RICH = os.getenv("TYPER_USE_RICH", True)
+HAS_RICH = parse_boolean_env_var(os.getenv("TYPER_USE_RICH"), default=True)
 
 if HAS_RICH:
     DEFAULT_MARKUP_MODE: MarkupMode = "rich"
-else:  # pragma: no cover
+else:
     DEFAULT_MARKUP_MODE = None
 
 

typer/utils.py

@@ -1,7 +1,7 @@
 import inspect
 import sys
 from copy import copy
-from typing import Any, Callable, cast
+from typing import Any, Callable, Optional, cast
 
 from ._typing import Annotated, get_args, get_origin, get_type_hints
 from .models import ArgumentInfo, OptionInfo, ParameterInfo, ParamMeta
@@ -188,3 +188,14 @@ def get_params_from_function(func: Callable[..., Any]) -> dict[str, ParamMeta]:
             name=param.name, default=default, annotation=annotation
         )
     return params
+
+
+def parse_boolean_env_var(env_var_value: Optional[str], default: bool) -> bool:
+    if env_var_value is None:
+        return default
+    value = env_var_value.lower()
+    if value in ("y", "yes", "t", "true", "on", "1"):
+        return True
+    if value in ("n", "no", "f", "false", "off", "0"):
+        return False
+    return default