display which theme is the default one in colored output

CHANGELOG.md

@@ -33,6 +33,7 @@
 - Relax syntax mapping rule restrictions to allow brace expansion #2865 (@cyqsimon)
 - Apply clippy fixes #2864 (@cyqsimon)
 - Faster startup by offloading glob matcher building to a worker thread #2868 (@cyqsimon)
+- Display which theme is the default one in colored output, see #2838 (@sblondon)
 
 ## Syntaxes
 

src/bin/bat/main.rs

@@ -30,6 +30,7 @@ use directories::PROJECT_DIRS;
 use globset::GlobMatcher;
 
 use bat::{
+    assets::HighlightingAssets,
     config::Config,
     controller::Controller,
     error::*,
@@ -200,11 +201,18 @@ pub fn list_themes(cfg: &Config, config_dir: &Path, cache_dir: &Path) -> Result<
     let mut stdout = stdout.lock();
 
     if config.colored_output {
+        let default_theme = HighlightingAssets::default_theme();
         for theme in assets.themes() {
+            let default_theme_info = if default_theme == theme {
+                " (default)"
+            } else {
+                ""
+            };
             writeln!(
                 stdout,
-                "Theme: {}\n",
-                Style::new().bold().paint(theme.to_string())
+                "Theme: {}{}\n",
+                Style::new().bold().paint(theme.to_string()),
+                default_theme_info
             )?;
             config.theme = theme.to_string();
             Controller::new(&config, &assets)

tests/integration_tests.rs

@@ -272,6 +272,24 @@ fn squeeze_limit_line_numbers() {
         .stdout("   1 line 1\n   2 \n   3 \n   4 \n   5 line 5\n   6 \n   7 \n   8 \n   9 \n  10 \n  20 line 20\n  21 line 21\n  22 \n  23 \n  24 line 24\n  25 \n  26 line 26\n  27 \n  28 \n  29 \n  30 line 30\n");
 }
 
+#[test]
+fn list_themes() {
+    #[cfg(target_os = "macos")]
+    let default_theme_chunk = "Monokai Extended Light\x1B[0m (default)";
+
+    #[cfg(not(target_os = "macos"))]
+    let default_theme_chunk = "Monokai Extended\x1B[0m (default)";
+
+    bat()
+        .arg("--color=always")
+        .arg("--list-themes")
+        .assert()
+        .success()
+        .stdout(predicate::str::contains("DarkNeon").normalize())
+        .stdout(predicate::str::contains(default_theme_chunk).normalize())
+        .stdout(predicate::str::contains("Output the square of a number.").normalize());
+}
+
 #[test]
 #[cfg_attr(any(not(feature = "git"), target_os = "windows"), ignore)]
 fn short_help() {