Better color detection

Cargo.toml

@@ -17,6 +17,7 @@ path = "src/main.rs"
 [dependencies]
 ansi_term = "0.12.0"
 app_dirs = { version = "2", package = "app_dirs2" }
+atty = "0.2"
 docopt = "1"
 env_logger = { version = "0.7", optional = true }
 flate2 = "1"

bash_tealdeer

@@ -17,6 +17,10 @@ _tealdeer()
 			COMPREPLY=( $(compgen -W 'linux osx sunos windows' -- "${cur}") )
 			return
 			;;
+		--color)
+			COMPREPLY=( $(compgen -W 'always auto never' -- "${cur}") )
+			return
+			;;
 	esac
 
 	if [[ $cur == -* ]]; then

fish_tealdeer

@@ -15,6 +15,7 @@ complete -c tldr -s m -l markdown    -d 'Display the raw markdown instead of ren
 complete -c tldr -s q -l quiet       -d 'Suppress informational messages.' -f
 complete -c tldr      -l config-path -d 'Show config file path.' -f
 complete -c tldr      -l seed-config -d 'Create a basic config.' -f
+complete -c tldr      -l color       -d 'Controls when to use color.' -xa 'always auto never'
 
 function __tealdeer_entries
     tldr --list | string replace -a -i -r "\,\s" "\n"

src/main.rs

@@ -16,14 +16,16 @@
 #[cfg(feature = "logging")]
 extern crate env_logger;
 
+use std::env;
 use std::fs::File;
 use std::io::BufRead;
 use std::io::BufReader;
 use std::path::{Path, PathBuf};
 use std::process;
 
-use ansi_term::Color;
+use ansi_term::{Color, Style};
 use app_dirs::AppInfo;
+use atty::Stream;
 use docopt::Docopt;
 #[cfg(not(target_os = "windows"))]
 use pager::Pager;
@@ -41,7 +43,7 @@ use crate::config::{get_config_path, make_default_config, Config, MAX_CACHE_AGE}
 use crate::error::TealdeerError::{CacheError, ConfigError, UpdateError};
 use crate::formatter::print_lines;
 use crate::tokenizer::Tokenizer;
-use crate::types::OsType;
+use crate::types::{ColorOptions, OsType};
 
 const NAME: &str = "tealdeer";
 const APP_INFO: AppInfo = AppInfo {
@@ -69,6 +71,7 @@ Options:
     -q --quiet          Suppress informational messages
     --config-path       Show config file path
     --seed-config       Create a basic config
+    --color <when>      Control when to use color [always, auto, never] [default: auto]
 
 Examples:
 
@@ -104,6 +107,7 @@ struct Args {
     flag_config_path: bool,
     flag_seed_config: bool,
     flag_markdown: bool,
+    flag_color: ColorOptions,
 }
 
 /// Print page by path
@@ -144,15 +148,23 @@ fn should_update_cache(args: &Args, config: &Config) -> bool {
 }
 
 /// Check the cache for freshness
-fn check_cache(args: &Args) {
+fn check_cache(args: &Args, enable_styles: bool) {
     match Cache::last_update() {
         Some(ago) if ago > MAX_CACHE_AGE => {
             if args.flag_quiet {
                 return;
             }
+
+            // Only use color if enabled
+            let warning_style = if enable_styles {
+                Style::new().fg(Color::Yellow)
+            } else {
+                Style::default()
+            };
+
             eprintln!(
                 "{}",
-                Color::Yellow.paint(format!(
+                warning_style.paint(format!(
                     "The cache hasn't been updated for more than {} days.\n\
                          You should probably run `tldr --update` soon.",
                     MAX_CACHE_AGE.as_secs() / 24 / 3600
@@ -305,9 +317,23 @@ fn main() {
 
     // Determine the usage of styles
     #[cfg(target_os = "windows")]
-    let enable_styles = ansi_term::enable_ansi_support().is_ok();
+    let ansi_support = ansi_term::enable_ansi_support().is_ok();
     #[cfg(not(target_os = "windows"))]
-    let enable_styles = true;
+    let ansi_support = true;
+
+    let enable_styles = match args.flag_color {
+        // Attempt to use styling if instructed
+        ColorOptions::Always => true,
+        // Enable styling if:
+        // * There is `ansi_support`
+        // * NO_COLOR env var isn't set: https://no-color.org/
+        // * The output stream is stdout (not being piped)
+        ColorOptions::Auto => {
+            ansi_support && env::var_os("NO_COLOR").is_none() && atty::is(Stream::Stdout)
+        }
+        // Disable styling
+        ColorOptions::Never => false,
+    };
 
     // Look up config file, if none is found fall back to default config.
     let config = match Config::load(enable_styles) {
@@ -363,7 +389,7 @@ fn main() {
     if args.flag_list {
         if !cache_updated {
             // Check cache for freshness
-            check_cache(&args);
+            check_cache(&args, enable_styles);
         }
 
         // Get list of pages
@@ -387,7 +413,7 @@ fn main() {
 
         if !cache_updated {
             // Check cache for freshness
-            check_cache(&args);
+            check_cache(&args, enable_styles);
         }
 
         // Search for command in cache

src/types.rs

@@ -27,6 +27,14 @@ impl fmt::Display for OsType {
     }
 }
 
+#[derive(Debug, Eq, PartialEq, Copy, Clone, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum ColorOptions {
+    Always,
+    Auto,
+    Never,
+}
+
 #[derive(Debug, Eq, PartialEq)]
 pub enum LineType {
     Empty,

tests/inkscape-default-no-color.expected

@@ -0,0 +1,28 @@
+
+  An SVG (Scalable Vector Graphics) editing program.
+  Use -z to not open the GUI and only process files in the console.
+
+  Open an SVG file in the Inkscape GUI:
+
+      inkscape filename.svg
+
+  Export an SVG file into a bitmap with the default format (PNG) and the default resolution (90 DPI):
+
+      inkscape filename.svg -e filename.png
+
+  Export an SVG file into a bitmap of 600x400 pixels (aspect ratio distortion may occur):
+
+      inkscape filename.svg -e filename.png -w 600 -h 400
+
+  Export a single object, given its ID, into a bitmap:
+
+      inkscape filename.svg -i id -e object.png
+
+  Export an SVG document to PDF, converting all texts to paths:
+
+      inkscape filename.svg | inkscape | inkscape --export-pdf=inkscape.pdf | inkscape | inkscape --export-text-to-path
+
+  Duplicate the object with id="path123", rotate the duplicate 90 degrees, save the file, and quit Inkscape:
+
+      inkscape filename.svg --select=path123 --verb=EditDuplicate --verb=ObjectRotate90 --verb=FileSave --verb=FileQuit
+

tests/lib.rs

@@ -241,7 +241,12 @@ fn test_markdown_rendering() {
         .stdout(similar(expected));
 }
 
-fn _test_correct_rendering(input_file: &str, filename: &str) {
+fn _test_correct_rendering(
+    input_file: &str,
+    filename: &str,
+    expected: &'static str,
+    color_option: &str,
+) {
     let testenv = TestEnv::new();
 
     // Create input file
@@ -250,10 +255,9 @@ fn _test_correct_rendering(input_file: &str, filename: &str) {
     let mut file = File::create(&file_path).unwrap();
     file.write_all(input_file.as_bytes()).unwrap();
 
-    let expected = include_str!("inkscape-default.expected");
     testenv
         .command()
-        .args(&["-f", &file_path.to_str().unwrap()])
+        .args(&["--color", color_option, "-f", &file_path.to_str().unwrap()])
         .assert()
         .success()
         .stdout(similar(expected));
@@ -262,13 +266,46 @@ fn _test_correct_rendering(input_file: &str, filename: &str) {
 /// An end-to-end integration test for direct file rendering (v1 syntax).
 #[test]
 fn test_correct_rendering_v1() {
-    _test_correct_rendering(include_str!("inkscape-v1.md"), "inkscape-v1.md");
+    _test_correct_rendering(
+        include_str!("inkscape-v1.md"),
+        "inkscape-v1.md",
+        include_str!("inkscape-default.expected"),
+        "always",
+    );
 }
 
 /// An end-to-end integration test for direct file rendering (v2 syntax).
 #[test]
 fn test_correct_rendering_v2() {
-    _test_correct_rendering(include_str!("inkscape-v2.md"), "inkscape-v2.md");
+    _test_correct_rendering(
+        include_str!("inkscape-v2.md"),
+        "inkscape-v2.md",
+        include_str!("inkscape-default.expected"),
+        "always",
+    );
+}
+
+#[test]
+/// An end-to-end integration test for direct file rendering with the `--color auto` option. This
+/// will not use styling since output is not stdout.
+fn test_rendering_color_auto() {
+    _test_correct_rendering(
+        include_str!("inkscape-v2.md"),
+        "inkscape-v2.md",
+        include_str!("inkscape-default-no-color.expected"),
+        "auto",
+    );
+}
+
+#[test]
+/// An end-to-end integration test for direct file rendering with the `--color never` option.
+fn test_rendering_color_never() {
+    _test_correct_rendering(
+        include_str!("inkscape-v2.md"),
+        "inkscape-v2.md",
+        include_str!("inkscape-default-no-color.expected"),
+        "never",
+    );
 }
 
 /// An end-to-end integration test for rendering with constom syntax config.
@@ -299,7 +336,7 @@ fn test_correct_rendering_with_config() {
 
     testenv
         .command()
-        .args(&["-f", &file_path.to_str().unwrap()])
+        .args(&["--color", "always", "-f", &file_path.to_str().unwrap()])
         .assert()
         .success()
         .stdout(similar(expected));

zsh_tealdeer

@@ -25,6 +25,11 @@ _tealdeer() {
 	"($I -q --quiet)"{-q,--quiet}"[Suppress informational messages]"
 	"($I)--config-path[Show config file path]"
 	"($I)--seed-config[Create a basic config]"
+	"($I --color)"{--color}'[Controls when to use color]:when:((
+	    always
+	    auto
+	    never
+        ))'
 	'(- *)'{-h,--help}'[Display help]'
     	'(- *)'{-v,--version}'[Show version information]'
     	'*:file:_files'