test: Add unit tests for index building and scanning functionality (#9)

src/patterns/mod.rs

@@ -60,6 +60,7 @@ impl FromStr for Severity {
 
 /// One AST pattern with a tree-sitter query and meta-data.
 #[derive(Debug, Clone, Serialize)]
+#[derive(PartialEq)]
 pub struct Pattern {
     /// Unique identifier (snake-case preferred).
     pub id: &'static str,
@@ -113,3 +114,35 @@ pub fn load(lang: &str) -> Vec<Pattern> {
     let key = lang.to_ascii_lowercase();
     REGISTRY.get(key.as_str()).copied().unwrap_or(&[]).to_vec()
 }
+
+#[test]
+fn severity_as_db_str_roundtrip() {
+  for &s in &[Severity::High, Severity::Medium, Severity::Low] {
+    let db = s.as_db_str();
+    assert!(matches!(db, "HIGH" | "MEDIUM" | "LOW"));
+    
+    assert_eq!(db.parse::<Severity>().unwrap(), s);
+    assert_eq!(db.to_lowercase().parse::<Severity>().unwrap(), s);
+  }
+}
+
+#[test]
+fn severity_display_contains_uppercase_name() {
+  assert!(Severity::High.to_string().contains("HIGH"));
+  assert!(Severity::Medium.to_string().contains("MEDIUM"));
+  assert!(Severity::Low.to_string().contains("LOW"));
+}
+
+#[test]
+fn load_returns_correct_pattern_slices() {
+  let rust = load("rust");
+  assert!(!rust.is_empty(), "Rust patterns should be loaded");
+
+  let ts   = load("typescript");
+  let tsx  = load("tsx");
+  assert_eq!(ts, tsx, "alias ‘tsx’ must map to TypeScript patterns");
+  
+  assert_eq!(load("RUST"), rust);
+  
+  assert!(load("brainfuck").is_empty());
+}