test: check output when --list-themes parameter used

Co-authored-by: Martin Nordholts <enselic@gmail.com>

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, see #2838 (@sblondon)
 
 ## Syntaxes
 

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() {