add borrow rate tests

Author: 0xbigz

programs/drift/src/controller/spot_balance/tests.rs

@@ -8,6 +8,7 @@ use crate::controller::spot_balance::*;
 use crate::controller::spot_position::update_spot_balances_and_cumulative_deposits_with_limits;
 use crate::create_account_info;
 use crate::create_anchor_account_info;
+use crate::math::constants::PERCENTAGE_PRECISION;
 use crate::math::constants::{
     AMM_RESERVE_PRECISION, BASE_PRECISION_I128, BASE_PRECISION_I64, LIQUIDATION_FEE_PRECISION,
     PEG_PRECISION, PRICE_PRECISION_I64, PRICE_PRECISION_U64, QUOTE_PRECISION, QUOTE_PRECISION_I128,
@@ -54,7 +55,6 @@ pub fn check_perp_market_valid(
 }
 
 
-
     #[test]
     fn test_meme_interest_rate() {
         let perp_market_map = PerpMarketMap::empty();
@@ -104,6 +104,21 @@ pub fn check_perp_market_valid(
 
         assert_eq!(meme_market.cumulative_borrow_interest, 10080236295);
 
+
+        let rate = calculate_borrow_rate(&meme_market, PERCENTAGE_PRECISION/2).unwrap();
+        assert_eq!(rate, 107_142);
+
+        let rate = calculate_borrow_rate(&meme_market, 850_000).unwrap();
+        assert_eq!(rate, 392_500);
+
+        let rate = calculate_borrow_rate(&meme_market, 990_000).unwrap();
+        assert_eq!(rate, 2_575_000);
+
+        let rate = calculate_borrow_rate(&meme_market, PERCENTAGE_PRECISION).unwrap();
+        assert_eq!(rate, 5_000_000);
+
+        assert_eq!(meme_market.max_borrow_rate, 5000000);
+
     }