add testing module (#585)

Author: Dev Kalra

target_chains/cosmwasm/pyth-sdk-cw/src/lib.rs

@@ -1,4 +1,6 @@
 pub mod error;
+pub mod testing;
+
 pub use pyth_sdk::{
     Price,
     PriceFeed,

target_chains/cosmwasm/pyth-sdk-cw/src/testing.rs

@@ -0,0 +1,87 @@
+use {
+    crate::{
+        error::PythContractError,
+        PriceFeed,
+        PriceFeedResponse,
+        PriceIdentifier,
+        QueryMsg,
+    },
+    cosmwasm_std::{
+        from_binary,
+        to_binary,
+        Binary,
+        Coin,
+        ContractResult,
+        QuerierResult,
+        SystemError,
+        SystemResult,
+    },
+    std::{
+        collections::HashMap,
+        time::Duration,
+        u128,
+    },
+};
+
+/// Mock version of Pyth for testing cosmwasm contracts.
+/// This mock stores some price feeds and responds to query messages.
+#[derive(Clone)]
+pub struct MockPyth {
+    pub valid_time_period: Duration,
+    pub fee_per_vaa:       Coin,
+    pub feeds:             HashMap<PriceIdentifier, PriceFeed>,
+}
+
+impl MockPyth {
+    /// Create a new `MockPyth`. You can either provide the full list of price feeds up front,
+    /// or add them later via `add_feed`.
+    pub fn new(valid_time_period: Duration, fee_per_vaa: Coin, feeds: &[PriceFeed]) -> Self {
+        let mut feeds_map = HashMap::new();
+        for feed in feeds {
+            feeds_map.insert(feed.id, *feed);
+        }
+
+        MockPyth {
+            valid_time_period,
+            fee_per_vaa,
+            feeds: feeds_map,
+        }
+    }
+
+    /// Add a price feed that will be returned on queries.
+    pub fn add_feed(&mut self, feed: PriceFeed) {
+        self.feeds.insert(feed.id, feed);
+    }
+
+    /// TODO: Update this with example contracts -> Handler for processing query messages. See the tests in `contract.rs` for how to use this
+    /// handler within your tests.
+    pub fn handle_wasm_query(&self, msg: &Binary) -> QuerierResult {
+        let query_msg = from_binary::<QueryMsg>(msg);
+        match query_msg {
+            Ok(QueryMsg::PriceFeed { id }) => match self.feeds.get(&id) {
+                Some(feed) => {
+                    SystemResult::Ok(to_binary(&PriceFeedResponse { price_feed: *feed }).into())
+                }
+                None => SystemResult::Ok(ContractResult::from(Err(
+                    PythContractError::PriceFeedNotFound,
+                ))),
+            },
+            Ok(QueryMsg::GetValidTimePeriod) => {
+                SystemResult::Ok(to_binary(&self.valid_time_period).into())
+            }
+            Ok(QueryMsg::GetUpdateFee { vaas }) => {
+                let new_amount = self
+                    .fee_per_vaa
+                    .amount
+                    .u128()
+                    .checked_mul(vaas.len() as u128)
+                    .unwrap();
+                SystemResult::Ok(to_binary(&Coin::new(new_amount, &self.fee_per_vaa.denom)).into())
+            }
+            Err(_e) => SystemResult::Err(SystemError::InvalidRequest {
+                error:   "Invalid message".into(),
+                request: msg.clone(),
+            }),
+        }
+    }
+}