refactor: modularize codebase and add 404 unit tests (#13)

compliance-agent/src/pipeline/dedup.rs

@@ -8,3 +8,51 @@ pub fn compute_fingerprint(parts: &[&str]) -> String {
     }
     hex::encode(hasher.finalize())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fingerprint_is_deterministic() {
+        let a = compute_fingerprint(&["repo1", "rule-x", "src/main.rs", "42"]);
+        let b = compute_fingerprint(&["repo1", "rule-x", "src/main.rs", "42"]);
+        assert_eq!(a, b);
+    }
+
+    #[test]
+    fn fingerprint_changes_with_different_input() {
+        let a = compute_fingerprint(&["repo1", "rule-x", "src/main.rs", "42"]);
+        let b = compute_fingerprint(&["repo1", "rule-x", "src/main.rs", "43"]);
+        assert_ne!(a, b);
+    }
+
+    #[test]
+    fn fingerprint_is_valid_hex_sha256() {
+        let fp = compute_fingerprint(&["hello"]);
+        assert_eq!(fp.len(), 64, "SHA-256 hex should be 64 chars");
+        assert!(fp.chars().all(|c| c.is_ascii_hexdigit()));
+    }
+
+    #[test]
+    fn fingerprint_empty_parts() {
+        let fp = compute_fingerprint(&[]);
+        // Should still produce a valid hash (of empty input)
+        assert_eq!(fp.len(), 64);
+    }
+
+    #[test]
+    fn fingerprint_order_matters() {
+        let a = compute_fingerprint(&["a", "b"]);
+        let b = compute_fingerprint(&["b", "a"]);
+        assert_ne!(a, b);
+    }
+
+    #[test]
+    fn fingerprint_separator_prevents_collision() {
+        // "ab" + "c" vs "a" + "bc" should differ because of the "|" separator
+        let a = compute_fingerprint(&["ab", "c"]);
+        let b = compute_fingerprint(&["a", "bc"]);
+        assert_ne!(a, b);
+    }
+}