Merge pull request #1813 from CosmWasm/cast_deps_to_empty

feat: Provide native way to cast deps to empty

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to
 ### Added
 
 - cosmwasm-std: Implement `Not` for `Uint{64,128,256}` ([#1799]).
+- cosmwasm-std: Implement `into_empty` for `QuerierWrapper`, `Deps` and
+  `DepsMut`.
 
 [#1799]: https://github.com/CosmWasm/cosmwasm/pull/1799
 

packages/std/src/deps.rs

@@ -69,6 +69,28 @@ impl<'a, C: CustomQuery> DepsMut<'a, C> {
             querier: self.querier,
         }
     }
+
+    /// This allows to convert any `DepsMut` into one generic over `Empty` custom
+    /// query type.
+    pub fn into_empty(self) -> DepsMut<'a, Empty> {
+        DepsMut {
+            storage: self.storage,
+            api: self.api,
+            querier: self.querier.into_empty(),
+        }
+    }
+}
+
+impl<'a, C: CustomQuery> Deps<'a, C> {
+    /// This allows to convert any `Deps` into one generic over `Empty` custom
+    /// query type.
+    pub fn into_empty(self) -> Deps<'a, Empty> {
+        Deps {
+            storage: self.storage,
+            api: self.api,
+            querier: self.querier.into_empty(),
+        }
+    }
 }
 
 #[cfg(test)]
@@ -98,12 +120,13 @@ mod tests {
         query(deps.as_ref())
     }
 
+    #[derive(Clone, Serialize, Deserialize)]
+    struct MyQuery;
+    impl CustomQuery for MyQuery {}
+
     #[test]
     fn deps_implements_copy() {
         impl CustomQuery for u64 {}
-        #[derive(Clone, Serialize, Deserialize)]
-        struct MyQuery;
-        impl CustomQuery for MyQuery {}
 
         // With C: Copy
         let owned = OwnedDeps::<_, _, _, u64> {
@@ -127,4 +150,20 @@ mod tests {
         let _copy1 = deps;
         let _copy2 = deps;
     }
+
+    #[test]
+    fn deps_to_empty() {
+        let mut owned = OwnedDeps::<_, _, _, MyQuery> {
+            storage: MockStorage::default(),
+            api: MockApi::default(),
+            querier: MockQuerier::<u64>::new(&[]),
+            custom_query_type: PhantomData,
+        };
+
+        let deps_mut: DepsMut<MyQuery> = owned.as_mut();
+        let _: DepsMut<Empty> = deps_mut.into_empty();
+
+        let deps: Deps<MyQuery> = owned.as_ref();
+        let _: Deps<Empty> = deps.into_empty();
+    }
 }

packages/std/src/traits.rs

@@ -225,6 +225,15 @@ impl<'a, C: CustomQuery> QuerierWrapper<'a, C> {
         }
     }
 
+    /// This allows to convert any `QuerierWrapper` into a `QuerierWrapper` generic
+    /// over `Empty` custom query type.
+    pub fn into_empty(self) -> QuerierWrapper<'a, Empty> {
+        QuerierWrapper {
+            querier: self.querier,
+            custom_query_type: PhantomData,
+        }
+    }
+
     /// Makes the query and parses the response.
     ///
     /// Any error (System Error, Error or called contract, or Parse Error) are flattened into
@@ -441,6 +450,8 @@ impl<'a, C: CustomQuery> QuerierWrapper<'a, C> {
 
 #[cfg(test)]
 mod tests {
+    use serde::Deserialize;
+
     use super::*;
     use crate::testing::MockQuerier;
     use crate::{coins, from_slice, Uint128};
@@ -571,4 +582,16 @@ mod tests {
             } if msg == "Querier system error: No such contract: foobar"
         ));
     }
+
+    #[test]
+    fn querier_into_empty() {
+        #[derive(Clone, Serialize, Deserialize)]
+        struct MyQuery;
+        impl CustomQuery for MyQuery {}
+
+        let querier: MockQuerier<MyQuery> = MockQuerier::new(&[]);
+        let wrapper = QuerierWrapper::<MyQuery>::new(&querier);
+
+        let _: QuerierWrapper<Empty> = wrapper.into_empty();
+    }
 }