Refine commission rate change tx

.changelog/unreleased/improvements/1973-refine-commission-tx.md

@@ -0,0 +1,2 @@
+- Add missing checks for the commission rate change tx and code clean-up
+  ([\#1973](https://github.com/anoma/namada/pull/1973))

proof_of_stake/src/lib.rs

@@ -2355,13 +2355,13 @@ pub fn change_validator_commission_rate<S>(
 where
     S: StorageRead + StorageWrite,
 {
-    // if new_rate < Uint::zero() {
-    //     return Err(CommissionRateChangeError::NegativeRate(
-    //         new_rate,
-    //         validator.clone(),
-    //     )
-    //     .into());
-    // }
+    if new_rate.is_negative() {
+        return Err(CommissionRateChangeError::NegativeRate(
+            new_rate,
+            validator.clone(),
+        )
+        .into());
+    }
 
     let max_change =
         read_validator_max_commission_rate_change(storage, validator)?;
@@ -2386,14 +2386,7 @@ where
         .get(storage, pipeline_epoch.prev(), &params)?
         .expect("Could not find a rate in given epoch");
 
-    // TODO: change this back if we use `Dec` type with a signed integer
-    // let change_from_prev = new_rate - rate_before_pipeline;
-    // if change_from_prev.abs() > max_change.unwrap() {
-    let change_from_prev = if new_rate > rate_before_pipeline {
-        new_rate - rate_before_pipeline
-    } else {
-        rate_before_pipeline - new_rate
-    };
+    let change_from_prev = new_rate.abs_diff(&rate_before_pipeline);
     if change_from_prev > max_change.unwrap() {
         return Err(CommissionRateChangeError::RateChangeTooLarge(
             change_from_prev,

shared/src/sdk/tx.rs

@@ -560,6 +560,18 @@ pub async fn build_validator_commission_change<
                 commission_rate,
                 max_commission_change_per_epoch,
             }) => {
+                if rate.is_negative() || rate > Dec::one() {
+                    edisplay_line!(
+                        IO,
+                        "New rate is outside of the allowed range of values \
+                         between 0.0 and 1.0."
+                    );
+                    if !tx_args.force {
+                        return Err(Error::from(
+                            TxError::InvalidCommissionRate(rate),
+                        ));
+                    }
+                }
                 if rate.abs_diff(&commission_rate)
                     > max_commission_change_per_epoch
                 {