[#2620] Update undelegate message to be more clear

core/staking_verifier_test.go

@@ -522,7 +522,7 @@ func TestCV31(t *testing.T) {
 	if _, err := VerifyAndCreateValidatorFromMsg(
 		statedb, postStakingEpoch, big.NewInt(0), msg,
 	); err == nil {
-		t.Error("expected", "have 4000000000000000000 want 5000000000000000000: self delegation can not be less than min_self_delegation", "got", nil)
+		t.Error("expected", "min_self_delegation 5000000000000000000, after delegation amount 4000000000000000000: self delegation can not be less than min_self_delegation", "got", nil)
 	}
 }
 

staking/types/validator.go

@@ -331,7 +331,8 @@ func (w *ValidatorWrapper) SanityCheck(
 			w.Delegations[0].Amount.Cmp(w.Validator.MinSelfDelegation) < 0 {
 			return errors.Wrapf(
 				errInvalidSelfDelegation,
-				"have %s want %s", w.Delegations[0].Amount.String(), w.Validator.MinSelfDelegation,
+				"min_self_delegation %s, after undelegation amount %s",
+				w.Validator.MinSelfDelegation, w.Delegations[0].Amount.String(),
 			)
 		}
 	}