Support the NO_COLOR environment variable.

See: https://no-color.org/

Author: jonathanslenders

src/prompt_toolkit/output/color_depth.py

@@ -42,6 +42,11 @@ def from_env(cls) -> ColorDepth | None:
         This is a way to enforce a certain color depth in all prompt_toolkit
         applications.
         """
+        # Disable color if a `NO_COLOR` environment variable is set.
+        # See: https://no-color.org/
+        if os.environ.get("NO_COLOR"):
+            return cls.DEPTH_1_BIT
+
         # Check the `PROMPT_TOOLKIT_COLOR_DEPTH` environment variable.
         all_values = [i.value for i in ColorDepth]
         if os.environ.get("PROMPT_TOOLKIT_COLOR_DEPTH") in all_values:

src/prompt_toolkit/styles/defaults.py

@@ -63,7 +63,9 @@
     # Completions menu.
     ("completion-menu", "bg:#bbbbbb #000000"),
     ("completion-menu.completion", ""),
-    ("completion-menu.completion.current", "bg:#888888 #ffffff"),
+    # (Note: for the current completion, we use 'reverse' on top of fg/bg
+    # colors. This is to have proper rendering with NO_COLOR=1).
+    ("completion-menu.completion.current", "fg:#888888 bg:#ffffff reverse"),
     ("completion-menu.meta.completion", "bg:#999999 #000000"),
     ("completion-menu.meta.completion.current", "bg:#aaaaaa #000000"),
     ("completion-menu.multi-column-meta", "bg:#aaaaaa #000000"),