refactor: api integration tests

pallets/api/src/fungibles/mod.rs

@@ -153,30 +153,30 @@
 			let id: AssetIdParameterOf<T> = id.into();
 
 			// If the new value is equal to the current allowance, do nothing.
 			let return_weight = if value == current_allowance {
 				Self::weight_approve(0, 0)
 			}
 			// If the new value is greater than the current allowance, approve the difference
 			// because `approve_transfer` works additively (see `pallet-assets`).
 			else if value > current_allowance {
 				AssetsOf::<T>::approve_transfer(
 					origin,
 					id,
 					spender,
 					value.saturating_sub(current_allowance),
 				)
 				.map_err(|e| e.with_weight(Self::weight_approve(1, 0)))?;
 				Self::weight_approve(1, 0)
 			} else {
 				// If the new value is less than the current allowance, cancel the approval and set the new value
 				AssetsOf::<T>::cancel_approval(origin.clone(), id.clone(), spender.clone())
 					.map_err(|e| e.with_weight(Self::weight_approve(0, 1)))?;
 				if value.is_zero() {
 					return Ok(Some(Self::weight_approve(0, 1)).into());
 				}
 				AssetsOf::<T>::approve_transfer(origin, id, spender, value)?;
 				Self::weight_approve(1, 1)
 			};
 			Ok(Some(return_weight).into())
 		}
 
@@ -214,23 +214,21 @@
 		) -> DispatchResultWithPostInfo {
 			let who = ensure_signed(origin.clone())
 				.map_err(|e| e.with_weight(Self::weight_approve(0, 0)))?;
-			let mut current_allowance = AssetsOf::<T>::allowance(id.clone(), &who, &spender);
+			let current_allowance = AssetsOf::<T>::allowance(id.clone(), &who, &spender);
 			let spender = T::Lookup::unlookup(spender);
 			let id: AssetIdParameterOf<T> = id.into();
 
 			if value.is_zero() {
 				return Ok(Some(Self::weight_approve(0, 0)).into());
 			}
-
-			current_allowance.saturating_reduce(value);
 			// Cancel the aproval and set the new value if `current_allowance` is more than zero.
 			AssetsOf::<T>::cancel_approval(origin.clone(), id.clone(), spender.clone())
 				.map_err(|e| e.with_weight(Self::weight_approve(0, 1)))?;
-
-			if current_allowance.is_zero() {
+			let new_allowance = current_allowance.saturating_sub(value);
+			if new_allowance.is_zero() {
 				return Ok(Some(Self::weight_approve(0, 1)).into());
 			}
-			AssetsOf::<T>::approve_transfer(origin, id, spender, current_allowance)?;
+			AssetsOf::<T>::approve_transfer(origin, id, spender, new_allowance)?;
 			Ok(().into())
 		}
 	}

pallets/api/src/fungibles/tests.rs

@@ -38,24 +38,6 @@ fn transfer_from_works() {
 	});
 }
 
-#[test]
-fn decrease_allowance_works() {
-	new_test_ext().execute_with(|| {
-		let amount: Balance = 100 * UNIT;
-		create_asset_mint_and_approve(ALICE, ASSET, ALICE, amount, BOB, amount);
-		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount);
-		// Owner balance is not changed if decreased by zero.
-		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, 0));
-		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount);
-		// Decrease allowance successfully.
-		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, amount / 2 - 1 * UNIT));
-		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount / 2 + 1 * UNIT);
-		// Saturating if current allowance is decreased more than the owner balance.
-		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, amount));
-		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), 0);
-	});
-}
-
 // Non-additive, sets new value.
 #[test]
 fn approve_works() {
@@ -94,6 +76,24 @@ fn increase_allowance_works() {
 	});
 }
 
+#[test]
+fn decrease_allowance_works() {
+	new_test_ext().execute_with(|| {
+		let amount: Balance = 100 * UNIT;
+		create_asset_mint_and_approve(ALICE, ASSET, ALICE, amount, BOB, amount);
+		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount);
+		// Owner balance is not changed if decreased by zero.
+		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, 0));
+		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount);
+		// Decrease allowance successfully.
+		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, amount / 2 - 1 * UNIT));
+		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), amount / 2 + 1 * UNIT);
+		// Saturating if current allowance is decreased more than the owner balance.
+		assert_ok!(Fungibles::decrease_allowance(signed(ALICE), ASSET, BOB, amount));
+		assert_eq!(Assets::allowance(ASSET, &ALICE, &BOB), 0);
+	});
+}
+
 #[test]
 fn total_supply_works() {
 	new_test_ext().execute_with(|| {