Merge pull request #974 from gregdhill/fix/withdraw-minimum

fix: don't allow vaults to withdraw below minimum

crates/vault-registry/src/lib.rs

@@ -849,6 +849,12 @@ impl<T: Config> Pallet<T> {
             Err(x) => return Err(x),
         };
 
+        ensure!(
+            new_collateral.is_zero()
+                || new_collateral.ge(&Self::get_minimum_collateral_vault(vault_id.currencies.collateral))?,
+            Error::<T>::InsufficientVaultCollateralAmount
+        );
+
         let is_below_threshold =
             Pallet::<T>::is_collateral_below_vault_secure_threshold(&new_collateral, &vault.backed_tokens()?, &vault)?;
         Ok(!is_below_threshold)

crates/vault-registry/src/tests.rs

@@ -205,6 +205,31 @@ fn register_vault_fails_when_already_registered() {
     });
 }
 
+#[test]
+fn should_check_withdraw_collateral() {
+    run_test(|| {
+        create_sample_vault();
+        VaultRegistry::get_minimum_collateral_vault
+            .mock_safe(move |currency_id| MockResult::Return(Amount::new(DEFAULT_COLLATERAL / 2, currency_id)));
+
+        // should allow withdraw all
+        assert_ok!(
+            VaultRegistry::is_allowed_to_withdraw_collateral(&DEFAULT_ID, &amount(DEFAULT_COLLATERAL)),
+            true,
+        );
+        // should allow withdraw above minimum
+        assert_ok!(
+            VaultRegistry::is_allowed_to_withdraw_collateral(&DEFAULT_ID, &amount(DEFAULT_COLLATERAL / 4)),
+            true,
+        );
+        // should not allow withdraw above zero, below minimum
+        assert_err!(
+            VaultRegistry::is_allowed_to_withdraw_collateral(&DEFAULT_ID, &amount(DEFAULT_COLLATERAL / 4 * 3)),
+            TestError::InsufficientVaultCollateralAmount,
+        );
+    });
+}
+
 #[test]
 fn try_increase_to_be_issued_tokens_succeeds() {
     run_test(|| {