Added ability to determine when to do markup (#17)

Adopts logic originally written for molecule that determines when
to use ANSI or not, relying on common environment variables.

setup.cfg

@@ -67,6 +67,7 @@ install_requires =
 test =
     mock>=3.0.5
     pytest-cov>=2.7.1
+    pytest-mock>=3.3.1
     pytest-plus
     pytest-xdist>=1.29.0
     pytest>=5.4.0

src/enrich/console.py

@@ -1,7 +1,8 @@
 """Module that helps integrating with rich library."""
 import io
+import os
 import sys
-from typing import IO, Any, List, Union
+from typing import IO, Any, List, TextIO, Union
 
 import rich.console as rich_console
 from rich.ansi import AnsiDecoder
@@ -62,6 +63,13 @@ def __init__(
         self.redirect = redirect
         self.soft_wrap = soft_wrap
 
+        # Unless user already mentioning terminal preference, we use our
+        # heuristic to make an informed decision.
+        if "force_terminal" not in kwargs:
+            kwargs["force_terminal"] = should_do_markup(
+                stream=kwargs.get("file", sys.stdout)
+            )
+
         super().__init__(*args, **kwargs)
         self.extended = True
         if self.redirect:
@@ -85,3 +93,48 @@ def print(self, *args, **kwargs) -> None:  # type: ignore
             decoder = AnsiDecoder()
             args = list(decoder.decode(text))  # type: ignore
         super().print(*args, **kwargs)
+
+
+# Based on Ansible implementation
+def to_bool(value: Any) -> bool:
+    """Return a bool for the arg."""
+    if value is None or isinstance(value, bool):
+        return bool(value)
+    if isinstance(value, str):
+        value = value.lower()
+    if value in ("yes", "on", "1", "true", 1):
+        return True
+    return False
+
+
+def should_do_markup(stream: TextIO = sys.stdout) -> bool:
+    """Decide about use of ANSI colors."""
+    py_colors = None
+
+    # https://xkcd.com/927/
+    for env_var in ["PY_COLORS", "CLICOLOR", "FORCE_COLOR", "ANSIBLE_FORCE_COLOR"]:
+        value = os.environ.get(env_var, None)
+        if value is not None:
+            py_colors = to_bool(value)
+            break
+
+    # If deliverately disabled colors
+    if os.environ.get("NO_COLOR", None):
+        return False
+
+    # User configuration requested colors
+    if py_colors is not None:
+        return to_bool(py_colors)
+
+    term = os.environ.get("TERM", "")
+    if "xterm" in term:
+        return True
+
+    if term == "dumb":
+        return False
+
+    # Use tty detection logic as last resort because there are numerous
+    # factors that can make isatty return a misleading value, including:
+    # - stdin.isatty() is the only one returning true, even on a real terminal
+    # - stderr returting false if user user uses a error stream coloring solution
+    return stream.isatty()

src/enrich/test/test_console.py

@@ -1,7 +1,7 @@
 """Tests for rich module."""
 import sys
 
-from enrich.console import Console
+from enrich.console import Console, should_do_markup
 
 
 def test_rich_console_ex() -> None:
@@ -52,5 +52,35 @@ def test_console_print_ansi() -> None:
     assert "#00ff00" in html_result
 
 
+def test_markup_detection_pycolors0(monkeypatch):
+    """Assure PY_COLORS=0 disables markup."""
+    monkeypatch.setenv("PY_COLORS", "0")
+    assert not should_do_markup()
+
+
+def test_markup_detection_pycolors1(monkeypatch):
+    """Assure PY_COLORS=1 enables markup."""
+    monkeypatch.setenv("PY_COLORS", "1")
+    assert should_do_markup()
+
+
+def test_markup_detection_tty_yes(mocker):
+    """Assures TERM=xterm enables markup."""
+    mocker.patch("sys.stdout.isatty", return_value=True)
+    mocker.patch("os.environ", {"TERM": "xterm"})
+    assert should_do_markup()
+    mocker.resetall()
+    mocker.stopall()
+
+
+def test_markup_detection_tty_no(mocker):
+    """Assures that if no tty is reported we disable markup."""
+    mocker.patch("os.environ", {})
+    mocker.patch("sys.stdout.isatty", return_value=False)
+    assert not should_do_markup()
+    mocker.resetall()
+    mocker.stopall()
+
+
 if __name__ == "__main__":
     test_console_print_ansi()

tox.ini

@@ -27,7 +27,7 @@ passenv =
 setenv =
     PIP_DISABLE_VERSION_CHECK=1
     PIP_USE_FEATURE={env:PIP_USE_FEATURE:2020-resolver}
-    PYTEST_REQPASS=5
+    PYTEST_REQPASS=9
     PYTHONDONTWRITEBYTECODE=1
     PYTHONUNBUFFERED=1
 commands =