suggestions

contracts/token/fungible/src/extensions/capped/storage.rs

@@ -8,8 +8,26 @@ use crate::{
 /// Storage key that maps to [`Cap`]
 pub const CAP_KEY: Symbol = symbol_short!("CAP");
 
+/// Set the maximum supply of tokens.
+///
+/// # Arguments
+///
+/// * `e` - Access to the Soroban environment.
+///
+/// # Errors
+///
+/// * [`FungibleTokenError::InvalidCap`] - Occurs when the provided cap is
+///   negative.
+///
+/// # Notes
+///
+/// We recommend using this function in the constructor of your smart contract.
+/// Cap functionality is designed to be used in junction with the `mintable`
+/// extension.
 pub fn set_cap(e: &Env, cap: i128) {
-    e.storage().instance().extend_ttl(INSTANCE_TTL_THRESHOLD, INSTANCE_EXTEND_AMOUNT);
+    if cap < 0 {
+        panic_with_error!(e, FungibleTokenError::InvalidCap);
+    }
     e.storage().instance().set(&CAP_KEY, &cap);
 }
 
@@ -19,27 +37,36 @@ pub fn set_cap(e: &Env, cap: i128) {
 ///
 /// * `e` - Access to the Soroban environment.
 ///
+/// # Errors
+///
+/// * [`FungibleTokenError::CapNotSet`] - Occurs when the cap has not been set.
+///
 /// # Returns
 ///
 /// the maximum supply of tokens.
 pub fn query_cap(e: &Env) -> i128 {
-    e.storage().instance().get(&CAP_KEY).unwrap_optimized()
+    e.storage()
+        .instance()
+        .get(&CAP_KEY)
+        .unwrap_or_else(|| panic_with_error!(e, FungibleTokenError::CapNotSet))
 }
 
-/// Panicks if new `amount` of tokens will exceed the maximum supply.
+/// Panics if new `amount` of tokens will exceed the maximum supply.
 ///
 /// # Arguments
 ///
 /// * `e` - Access to the Soroban environment.
 /// * `amount` - The new amount of tokens to be added to the total supply.
 ///
-/// # Notes
+/// # Errors
 ///
-/// We recommend using [`crate::burnable::burn_from()`] when implementing
-/// this function.
+/// * [`FungibleTokenError::CapNotSet`] - Occurs when the cap has not been set.
 pub fn check_cap(e: &Env, amount: i128) {
-    let cap: i128 = e.storage().instance().get(&CAP_KEY).unwrap_optimized();
-    e.storage().instance().extend_ttl(INSTANCE_TTL_THRESHOLD, INSTANCE_EXTEND_AMOUNT);
+    let cap: i128 = e
+        .storage()
+        .instance()
+        .get(&CAP_KEY)
+        .unwrap_or_else(|| panic_with_error!(e, FungibleTokenError::CapNotSet));
     let total_supply = e.storage().instance().get(&StorageKey::TotalSupply).unwrap_or(0);
     if cap < amount + total_supply {
         panic_with_error!(e, FungibleTokenError::ExceededCap)

contracts/token/fungible/src/extensions/mintable/mod.rs

@@ -35,14 +35,14 @@ pub trait FungibleMintable {
     /// We recommend using [`crate::mintable::mint()`] when implementing this
     /// function.
     ///
-    /// IMPORTANT: Please do not forget that, you probably will want to have
-    /// some authorization controls for minting tokens.
-    ///
-    /// NOTE: if you want to add `capped` functionality to this function,
+    /// If you want to add `capped` functionality to this function,
     /// we recommend using [`crate::capped::check_cap()`] when implementing this
     /// function. For more details on the `capped` functionality, check
     /// [`crate::extensions::capped`], and check the `fungible-capped`
     /// example.
+    ///
+    /// IMPORTANT: Please do not forget that, you probably will want to have
+    /// some authorization controls for minting tokens.
     fn mint(e: &Env, account: Address, amount: i128);
 }
 // ################## EVENTS ##################

contracts/token/fungible/src/fungible.rs

@@ -200,6 +200,8 @@ pub enum FungibleTokenError {
     ExceededCap = 206,
     /// Indicates the supplied `cap` is not a valid cap value.
     InvalidCap = 207,
+    /// Indicates the Cap was not set.
+    CapNotSet = 208,
 }
 
 // ################## EVENTS ##################

contracts/token/fungible/test_snapshots/extensions/capped/test/test_mint_exceeds_cap.1.json

@@ -45,7 +45,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ],
       [
@@ -66,7 +66,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ]
     ]

contracts/token/fungible/test_snapshots/extensions/capped/test/test_query_cap.1.json

@@ -58,7 +58,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ],
       [
@@ -79,7 +79,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ]
     ]

examples/fungible-capped/src/test.rs

@@ -11,14 +11,6 @@ fn create_client<'a>(e: &Env, cap: &i128) -> ExampleContractClient<'a> {
     ExampleContractClient::new(e, &address)
 }
 
-// #[test]
-// fn query_cap_works() {
-//     let e = Env::default();
-//     e.register(ExampleContract, (&1000,));
-
-//     assert_eq!(query_cap(&e), 1000);
-// }
-
 #[test]
 fn mint_under_cap() {
     let e = Env::default();

examples/fungible-capped/test_snapshots/test/mint_exceeds_cap.1.json

@@ -58,7 +58,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ],
       [
@@ -79,7 +79,7 @@
             },
             "ext": "v0"
           },
-          120960
+          4095
         ]
       ]
     ]