test: ensure startup message is correct

src/branding.rs

@@ -1,8 +1,18 @@
-pub fn startup_msg() {
+#[cfg(test)]
+use insta::assert_snapshot;
+
+pub fn startup_msg() -> String {
     let name = env!("CARGO_PKG_NAME");
     let version = env!("CARGO_PKG_VERSION");
     let authors = env!("CARGO_PKG_AUTHORS");
 
-    println!("{name} v{version} started.",);
-    println!("Copyright 2025 {authors}. All rights reserved.")
+    format!(
+        "{name} v{version} started.\n\
+        Copyright 2025 {authors}. All rights reserved."
+    )
+}
+
+#[test]
+fn test_startup_msg() {
+    assert_snapshot!(startup_msg())
 }