Add support for NO_COLOR and FORCE_COLOR (#7466)

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

changelog/7464.feature.rst

@@ -0,0 +1,3 @@
+Added support for ``NO_COLOR`` and ``FORCE_COLOR`` environment variables to control colored output.
+
+For more information, see `the docs <https://docs.pytest.org/en/stable/reference.html#environment-variables>`__.

doc/en/reference.rst

@@ -988,10 +988,20 @@ Environment variables that can be used to change pytest's behavior.
 This contains a command-line (parsed by the py:mod:`shlex` module) that will be **prepended** to the command line given
 by the user, see :ref:`adding default options` for more information.
 
+.. envvar:: PYTEST_CURRENT_TEST
+
+This is not meant to be set by users, but is set by pytest internally with the name of the current test so other
+processes can inspect it, see :ref:`pytest current test env` for more information.
+
 .. envvar:: PYTEST_DEBUG
 
 When set, pytest will print tracing and debug information.
 
+.. envvar:: PYTEST_DISABLE_PLUGIN_AUTOLOAD
+
+When set, disables plugin auto-loading through setuptools entrypoints. Only explicitly specified plugins will be
+loaded.
+
 .. envvar:: PYTEST_PLUGINS
 
 Contains comma-separated list of modules that should be loaded as plugins:
@@ -1000,15 +1010,22 @@ Contains comma-separated list of modules that should be loaded as plugins:
 
     export PYTEST_PLUGINS=mymodule.plugin,xdist
 
-.. envvar:: PYTEST_DISABLE_PLUGIN_AUTOLOAD
+.. envvar:: PY_COLORS
 
-When set, disables plugin auto-loading through setuptools entrypoints. Only explicitly specified plugins will be
-loaded.
+When set to ``1``, pytest will use color in terminal output.
+When set to ``0``, pytest will not use color.
+``PY_COLORS`` takes precedence over ``NO_COLOR`` and ``FORCE_COLOR``.
 
-.. envvar:: PYTEST_CURRENT_TEST
+.. envvar:: NO_COLOR
 
-This is not meant to be set by users, but is set by pytest internally with the name of the current test so other
-processes can inspect it, see :ref:`pytest current test env` for more information.
+When set (regardless of value), pytest will not use color in terminal output.
+``PY_COLORS`` takes precedence over ``NO_COLOR``, which takes precedence over ``FORCE_COLOR``.
+See `no-color.org <https://no-color.org/>`__ for other libraries supporting this community standard.
+
+.. envvar:: FORCE_COLOR
+
+When set (regardless of value), pytest will use color in terminal output.
+``PY_COLORS`` and ``NO_COLOR`` take precedence over ``FORCE_COLOR``.
 
 Exceptions
 ----------

src/_pytest/_io/terminalwriter.py

@@ -27,11 +27,12 @@ def should_do_markup(file: TextIO) -> bool:
         return True
     if os.environ.get("PY_COLORS") == "0":
         return False
+    if "NO_COLOR" in os.environ:
+        return False
+    if "FORCE_COLOR" in os.environ:
+        return True
     return (
-        hasattr(file, "isatty")
-        and file.isatty()
-        and os.environ.get("TERM") != "dumb"
-        and not (sys.platform.startswith("java") and os._name == "nt")
+        hasattr(file, "isatty") and file.isatty() and os.environ.get("TERM") != "dumb"
     )
 
 

testing/io/test_terminalwriter.py

@@ -154,8 +154,7 @@ def test_attr_hasmarkup() -> None:
     assert "\x1b[0m" in s
 
 
-def test_should_do_markup_PY_COLORS_eq_1(monkeypatch: MonkeyPatch) -> None:
-    monkeypatch.setitem(os.environ, "PY_COLORS", "1")
+def assert_color_set():
     file = io.StringIO()
     tw = terminalwriter.TerminalWriter(file)
     assert tw.hasmarkup
@@ -166,8 +165,7 @@ def test_should_do_markup_PY_COLORS_eq_1(monkeypatch: MonkeyPatch) -> None:
     assert "\x1b[0m" in s
 
 
-def test_should_do_markup_PY_COLORS_eq_0(monkeypatch: MonkeyPatch) -> None:
-    monkeypatch.setitem(os.environ, "PY_COLORS", "0")
+def assert_color_not_set():
     f = io.StringIO()
     f.isatty = lambda: True  # type: ignore
     tw = terminalwriter.TerminalWriter(file=f)
@@ -177,6 +175,34 @@ def test_should_do_markup_PY_COLORS_eq_0(monkeypatch: MonkeyPatch) -> None:
     assert s == "hello\n"
 
 
+def test_should_do_markup_PY_COLORS_eq_1(monkeypatch: MonkeyPatch) -> None:
+    monkeypatch.setitem(os.environ, "PY_COLORS", "1")
+    assert_color_set()
+
+
+def test_should_not_do_markup_PY_COLORS_eq_0(monkeypatch: MonkeyPatch) -> None:
+    monkeypatch.setitem(os.environ, "PY_COLORS", "0")
+    assert_color_not_set()
+
+
+def test_should_not_do_markup_NO_COLOR(monkeypatch: MonkeyPatch) -> None:
+    monkeypatch.setitem(os.environ, "NO_COLOR", "1")
+    assert_color_not_set()
+
+
+def test_should_do_markup_FORCE_COLOR(monkeypatch: MonkeyPatch) -> None:
+    monkeypatch.setitem(os.environ, "FORCE_COLOR", "1")
+    assert_color_set()
+
+
+def test_should_not_do_markup_NO_COLOR_and_FORCE_COLOR(
+    monkeypatch: MonkeyPatch,
+) -> None:
+    monkeypatch.setitem(os.environ, "NO_COLOR", "1")
+    monkeypatch.setitem(os.environ, "FORCE_COLOR", "1")
+    assert_color_not_set()
+
+
 class TestTerminalWriterLineWidth:
     def test_init(self) -> None:
         tw = terminalwriter.TerminalWriter()