min-gas-multiplier parameter should accept zero value

CHANGELOG.md

@@ -42,6 +42,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (evm) [tharsis#1118](https://github.com/tharsis/ethermint/pull/1118) Fix `Type()` `Account` method `EmptyCodeHash` comparison
 
+### Improvements
+
+- (feemarket) [tharsis#1120](https://github.com/tharsis/ethermint/pull/1120) Make `min-gas-multiplier` parameter accept zero value
+
 ## [v0.16.0] - 2022-06-06
 
 ### State Machine Breaking

x/feemarket/types/params.go

@@ -189,12 +189,12 @@ func validateMinGasMultiplier(i interface{}) error {
 		return fmt.Errorf("invalid parameter: nil")
 	}
 
-	if v.IsZero() || v.IsNegative() {
-		return fmt.Errorf("value cannot be zero or negative: %T", i)
+	if v.IsNegative() {
+		return fmt.Errorf("value cannot be negative: %s", v)
 	}
 
 	if v.GT(sdk.OneDec()) {
-		return fmt.Errorf("value cannot be greater than 1: %T", i)
+		return fmt.Errorf("value cannot be greater than 1: %s", v)
 	}
 	return nil
 }

x/feemarket/types/params_test.go

@@ -49,12 +49,17 @@ func (suite *ParamsTestSuite) TestParamsValidate() {
 			true,
 		},
 		{
-			"invalid: min gas multiplier zero",
+			"valid: min gas multiplier zero",
 			NewParams(true, 7, 3, 2000000000, int64(544435345345435345), DefaultMinGasPrice, sdk.ZeroDec()),
+			false,
+		},
+		{
+			"invalid: min gas multiplier is negative",
+			NewParams(true, 7, 3, 2000000000, int64(544435345345435345), DefaultMinGasPrice, sdk.NewDecWithPrec(-5, 1)),
 			true,
 		},
 		{
-			"invalid: min gas multiplier",
+			"invalid: min gas multiplier bigger than 1",
 			NewParams(true, 7, 3, 2000000000, int64(544435345345435345), sdk.NewDecWithPrec(20, 4), sdk.NewDec(2)),
 			true,
 		},