diff --git a/src/error.rs b/src/error.rs
index eb9d289..61ff017 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -10,6 +10,7 @@ pub enum Error {
 	NegativeNumbers,
 }
 
+#[derive(Debug)]
 pub enum PgError {
 	SqidsError(sqids::Error),
 	CustomError(Error),
diff --git a/src/lib.rs b/src/lib.rs
index 1fd28e1..d58c6af 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -214,3 +214,60 @@ fn sqids_decode_with_alphabet_min_length_blocklist(
 
 	Ok(sqids.decode(id).iter().map(|n| *n as i64).collect())
 }
+
+#[cfg(any(test, feature = "pg_test"))]
+#[pg_schema]
+mod tests {
+	use pgrx::prelude::*;
+	use std::collections::HashMap;
+
+	// @NOTE since this extension uses `https://crates.io/crates/sqids`, this repo does not include the standard Sqids unit tests (which are included
+	// in the external Rust library). Therefore, we are testing the SQL functions only.
+
+	#[pg_test]
+	fn test_sqids_encode() {
+		let tests: HashMap<&str, Option<String>> = HashMap::from([
+            ("SELECT sqids_encode(1, 2, 3)", Some("86Rf07".to_string())),
+            ("SELECT sqids_encode(10::smallint, 1, 2, 3)", Some("86Rf07xd4z".to_string())),
+            ("SELECT sqids_encode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 1, 2, 3)", Some("XRKUdQ".to_string())),
+            ("SELECT sqids_encode(array['86Rf07'], 1, 2, 3)", Some("se8ojk".to_string())),
+            ("SELECT sqids_encode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 10::smallint, 1, 2, 3)", Some("XRKUdQVBzg".to_string())),
+            ("SELECT sqids_encode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', array['XRKUdQ'], 1, 2, 3)", Some("WyXQfF".to_string())),
+            ("SELECT sqids_encode(10::smallint, array['86Rf07'], 1, 2, 3)", Some("se8ojkCQvX".to_string())),
+            ("SELECT sqids_encode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 10::smallint, array['XRKUdQVBzg'], 1, 2, 3)", Some("WyXQfFQ21T".to_string())),
+        ]);
+
+		for (sql, expected) in tests {
+			let result = Spi::get_one(sql).expect("Query failed");
+			assert_eq!(result, expected, "Failed on query: {}", sql);
+		}
+	}
+
+	#[pg_test]
+	fn test_sqids_decode() {
+		let tests: HashMap<&str, Option<Vec<i64>>> = HashMap::from([
+            ("SELECT sqids_decode('86Rf07')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode(10::smallint, '86Rf07xd4z')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 'XRKUdQ')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode(array['86Rf07'], 'se8ojk')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 10::smallint, 'XRKUdQVBzg')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', array['XRKUdQ'], 'WyXQfF')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode(10::smallint, array['86Rf07'], 'se8ojkCQvX')", Some(vec![1, 2, 3])),
+            ("SELECT sqids_decode('k3G7QAe51FCsPW92uEOyq4Bg6Sp8YzVTmnU0liwDdHXLajZrfxNhobJIRcMvKt', 10::smallint, array['XRKUdQVBzg'], 'WyXQfFQ21T')", Some(vec![1, 2, 3])),
+        ]);
+
+		for (sql, expected) in tests {
+			let result = Spi::get_one(sql).expect("Query failed");
+			assert_eq!(result, expected, "Failed on query: {}", sql);
+		}
+	}
+}
+
+#[cfg(test)]
+pub mod pg_test {
+	pub fn setup(_options: Vec<&str>) {}
+
+	pub fn postgresql_conf_options() -> Vec<&'static str> {
+		vec![]
+	}
+}