Use SemanticError in OfferBuilder::build

Author: jkczyz

lightning/src/offers/offer.rs

@@ -47,8 +47,7 @@
 //!     .issuer("Foo Bar".to_string())
 //!     .path(create_blinded_path())
 //!     .path(create_another_blinded_path())
-//!     .build()
-//!     .unwrap();
+//!     .build()?;
 //!
 //! // Encode as a bech32 string for use in a QR code.
 //! let encoded_offer = offer.to_string();
@@ -211,9 +210,9 @@ impl OfferBuilder {
 	}
 
 	/// Builds an [`Offer`] from the builder's settings.
-	pub fn build(self) -> Result<Offer, ()> {
+	pub fn build(self) -> Result<Offer, SemanticError> {
 		if self.offer.quantity_min() > self.offer.quantity_max() {
-			return Err(());
+			return Err(SemanticError::InvalidQuantity);
 		}
 
 		let mut bytes = Vec::new();
@@ -531,6 +530,7 @@ mod tests {
 	use core::num::NonZeroU64;
 	use core::time::Duration;
 	use ln::features::OfferFeatures;
+	use offers::parse::SemanticError;
 	use onion_message::{BlindedHop, BlindedPath};
 	use util::ser::Writeable;
 
@@ -884,11 +884,10 @@ mod tests {
 		assert_eq!(tlv_stream.quantity_min, None);
 		assert_eq!(tlv_stream.quantity_max, Some(9));
 
-		assert!(OfferBuilder::new("foo".into(), pubkey(42))
-			.quantity_range(ten..five)
-			.build()
-			.is_err()
-		);
+		match OfferBuilder::new("foo".into(), pubkey(42)).quantity_range(ten..five).build() {
+			Ok(_) => panic!("expected error"),
+			Err(e) => assert_eq!(e, SemanticError::InvalidQuantity),
+		}
 	}
 }