Merge pull request #982 from paper-lark/no-color

NO_COLOR environment variable support

man/exa.1.md

@@ -224,6 +224,12 @@ Specifies the number of spaces to print between an icon (see the ‘`--icons`’
 
 Different terminals display icons differently, as they usually take up more than one character width on screen, so there’s no “standard” number of spaces that exa can use to separate an icon from text. One space may place the icon too close to the text, and two spaces may place it too far away. So the choice is left up to the user to configure depending on their terminal emulator.
 
+## `NO_COLOR`
+
+Disables colours in the output (regardless of its value). Can be overridden by `--color` option.
+
+See `https://no-color.org/` for details.
+
 ## `LS_COLORS`, `EXA_COLORS`
 
 Specifies the colour scheme used to highlight files based on their name and kind, as well as highlighting metadata and parts of the UI.

src/options/theme.rs

@@ -5,7 +5,7 @@ use crate::theme::{Options, UseColours, ColourScale, Definitions};
 
 impl Options {
     pub fn deduce<V: Vars>(matches: &MatchedFlags<'_>, vars: &V) -> Result<Self, OptionsError> {
-        let use_colours = UseColours::deduce(matches)?;
+        let use_colours = UseColours::deduce(matches, vars)?;
         let colour_scale = ColourScale::deduce(matches)?;
 
         let definitions = if use_colours == UseColours::Never {
@@ -21,10 +21,15 @@ impl Options {
 
 
 impl UseColours {
-    fn deduce(matches: &MatchedFlags<'_>) -> Result<Self, OptionsError> {
+    fn deduce<V: Vars>(matches: &MatchedFlags<'_>, vars: &V) -> Result<Self, OptionsError> {
+        let default_value = match vars.get(vars::NO_COLOR) {
+            Some(_) => Self::Never,
+            None => Self::Automatic,
+        };
+
         let word = match matches.get_where(|f| f.matches(&flags::COLOR) || f.matches(&flags::COLOUR))? {
             Some(w)  => w,
-            None     => return Ok(Self::Automatic),
+            None => return Ok(default_value),
         };
 
         if word == "always" {
@@ -87,6 +92,16 @@ mod terminal_test {
             }
         };
 
+        ($name:ident:  $type:ident <- $inputs:expr, $env:expr;  $stricts:expr => $result:expr) => {
+            #[test]
+            fn $name() {
+                let env = $env;
+                for result in parse_for_test($inputs.as_ref(), TEST_ARGS, $stricts, |mf| $type::deduce(mf, &env)) {
+                    assert_eq!(result, $result);
+                }
+            }
+        };
+
         ($name:ident:  $type:ident <- $inputs:expr;  $stricts:expr => err $result:expr) => {
             #[test]
             fn $name() {
@@ -95,11 +110,39 @@ mod terminal_test {
                 }
             }
         };
+
+        ($name:ident:  $type:ident <- $inputs:expr, $env:expr;  $stricts:expr => err $result:expr) => {
+            #[test]
+            fn $name() {
+                let env = $env;
+                for result in parse_for_test($inputs.as_ref(), TEST_ARGS, $stricts, |mf| $type::deduce(mf, &env)) {
+                    assert_eq!(result.unwrap_err(), $result);
+                }
+            }
+        };
     }
 
     struct MockVars {
         ls: &'static str,
         exa: &'static str,
+        no_color: &'static str,
+    }
+
+    impl MockVars {
+        fn empty() -> MockVars {
+            return MockVars {
+                ls: "",
+                exa: "",
+                no_color: "",
+            };
+        }
+        fn with_no_color() -> MockVars {
+            return MockVars {
+                ls: "",
+                exa: "",
+                no_color: "true",
+            };
+        }
     }
 
     // Test impl that just returns the value it has.
@@ -111,6 +154,9 @@ mod terminal_test {
             else if name == vars::EXA_COLORS && ! self.exa.is_empty() {
                 Some(OsString::from(self.exa.clone()))
             }
+            else if name == vars::NO_COLOR && ! self.no_color.is_empty() {
+                Some(OsString::from(self.no_color.clone()))
+            }
             else {
                 None
             }
@@ -120,32 +166,33 @@ mod terminal_test {
 
 
     // Default
-    test!(empty:         UseColours <- [];                     Both => Ok(UseColours::Automatic));
+    test!(empty:         UseColours <- [], MockVars::empty();                     Both => Ok(UseColours::Automatic));
+    test!(empty_with_no_color: UseColours <- [], MockVars::with_no_color();             Both => Ok(UseColours::Never));
 
     // --colour
-    test!(u_always:      UseColours <- ["--colour=always"];    Both => Ok(UseColours::Always));
-    test!(u_auto:        UseColours <- ["--colour", "auto"];   Both => Ok(UseColours::Automatic));
-    test!(u_never:       UseColours <- ["--colour=never"];     Both => Ok(UseColours::Never));
+    test!(u_always:      UseColours <- ["--colour=always"], MockVars::empty();    Both => Ok(UseColours::Always));
+    test!(u_auto:        UseColours <- ["--colour", "auto"], MockVars::empty();   Both => Ok(UseColours::Automatic));
+    test!(u_never:       UseColours <- ["--colour=never"], MockVars::empty();     Both => Ok(UseColours::Never));
 
     // --color
-    test!(no_u_always:   UseColours <- ["--color", "always"];  Both => Ok(UseColours::Always));
-    test!(no_u_auto:     UseColours <- ["--color=auto"];       Both => Ok(UseColours::Automatic));
-    test!(no_u_never:    UseColours <- ["--color", "never"];   Both => Ok(UseColours::Never));
+    test!(no_u_always:   UseColours <- ["--color", "always"], MockVars::empty();  Both => Ok(UseColours::Always));
+    test!(no_u_auto:     UseColours <- ["--color=auto"], MockVars::empty();       Both => Ok(UseColours::Automatic));
+    test!(no_u_never:    UseColours <- ["--color", "never"], MockVars::empty();   Both => Ok(UseColours::Never));
 
     // Errors
-    test!(no_u_error:    UseColours <- ["--color=upstream"];   Both => err OptionsError::BadArgument(&flags::COLOR, OsString::from("upstream")));  // the error is for --color
-    test!(u_error:       UseColours <- ["--colour=lovers"];    Both => err OptionsError::BadArgument(&flags::COLOR, OsString::from("lovers")));    // and so is this one!
+    test!(no_u_error:    UseColours <- ["--color=upstream"], MockVars::empty();   Both => err OptionsError::BadArgument(&flags::COLOR, OsString::from("upstream"))); // the error is for --color
+    test!(u_error:       UseColours <- ["--colour=lovers"], MockVars::empty();    Both => err OptionsError::BadArgument(&flags::COLOR, OsString::from("lovers"))); // and so is this one!
 
     // Overriding
-    test!(overridden_1:  UseColours <- ["--colour=auto", "--colour=never"];  Last => Ok(UseColours::Never));
-    test!(overridden_2:  UseColours <- ["--color=auto",  "--colour=never"];  Last => Ok(UseColours::Never));
-    test!(overridden_3:  UseColours <- ["--colour=auto", "--color=never"];   Last => Ok(UseColours::Never));
-    test!(overridden_4:  UseColours <- ["--color=auto",  "--color=never"];   Last => Ok(UseColours::Never));
-
-    test!(overridden_5:  UseColours <- ["--colour=auto", "--colour=never"];  Complain => err OptionsError::Duplicate(Flag::Long("colour"), Flag::Long("colour")));
-    test!(overridden_6:  UseColours <- ["--color=auto",  "--colour=never"];  Complain => err OptionsError::Duplicate(Flag::Long("color"),  Flag::Long("colour")));
-    test!(overridden_7:  UseColours <- ["--colour=auto", "--color=never"];   Complain => err OptionsError::Duplicate(Flag::Long("colour"), Flag::Long("color")));
-    test!(overridden_8:  UseColours <- ["--color=auto",  "--color=never"];   Complain => err OptionsError::Duplicate(Flag::Long("color"),  Flag::Long("color")));
+    test!(overridden_1:  UseColours <- ["--colour=auto", "--colour=never"], MockVars::empty();  Last => Ok(UseColours::Never));
+    test!(overridden_2:  UseColours <- ["--color=auto",  "--colour=never"], MockVars::empty();  Last => Ok(UseColours::Never));
+    test!(overridden_3:  UseColours <- ["--colour=auto", "--color=never"], MockVars::empty();   Last => Ok(UseColours::Never));
+    test!(overridden_4:  UseColours <- ["--color=auto",  "--color=never"], MockVars::empty();   Last => Ok(UseColours::Never));
+
+    test!(overridden_5:  UseColours <- ["--colour=auto", "--colour=never"], MockVars::empty();  Complain => err OptionsError::Duplicate(Flag::Long("colour"), Flag::Long("colour")));
+    test!(overridden_6:  UseColours <- ["--color=auto",  "--colour=never"], MockVars::empty();  Complain => err OptionsError::Duplicate(Flag::Long("color"),  Flag::Long("colour")));
+    test!(overridden_7:  UseColours <- ["--colour=auto", "--color=never"], MockVars::empty();   Complain => err OptionsError::Duplicate(Flag::Long("colour"), Flag::Long("color")));
+    test!(overridden_8:  UseColours <- ["--color=auto",  "--color=never"], MockVars::empty();   Complain => err OptionsError::Duplicate(Flag::Long("color"),  Flag::Long("color")));
 
     test!(scale_1:  ColourScale <- ["--color-scale", "--colour-scale"];   Last => Ok(ColourScale::Gradient));
     test!(scale_2:  ColourScale <- ["--color-scale",                 ];   Last => Ok(ColourScale::Gradient));

src/options/vars.rs

@@ -15,6 +15,9 @@ pub static COLUMNS: &str = "COLUMNS";
 /// Environment variable used to datetime format.
 pub static TIME_STYLE: &str = "TIME_STYLE";
 
+/// Environment variable used to disable colors.
+/// See: https://no-color.org/
+pub static NO_COLOR: &str = "NO_COLOR";
 
 // exa-specific variables