Add cli test for slashing (#6102)

Reference: #5951

x/slashing/client/testutil/helpers.go

@@ -0,0 +1,33 @@
+package testutil
+
+import (
+	"fmt"
+	"github.com/cosmos/cosmos-sdk/tests"
+	"github.com/cosmos/cosmos-sdk/tests/cli"
+	"github.com/cosmos/cosmos-sdk/x/slashing"
+	"github.com/stretchr/testify/require"
+)
+
+// QuerySigningInfo returns the signing info for a validator
+func QuerySigningInfo(f *cli.Fixtures, val string) slashing.ValidatorSigningInfo {
+	cmd := fmt.Sprintf("%s query slashing signing-info %s %s", f.SimcliBinary, val, f.Flags())
+	res, errStr := tests.ExecuteT(f.T, cmd, "")
+	require.Empty(f.T, errStr)
+
+	var sinfo slashing.ValidatorSigningInfo
+	err := f.Cdc.UnmarshalJSON([]byte(res), &sinfo)
+	require.NoError(f.T, err)
+	return sinfo
+}
+
+// QuerySlashingParams returns query slashing params
+func QuerySlashingParams(f *cli.Fixtures) slashing.Params {
+	cmd := fmt.Sprintf("%s query slashing params %s", f.SimcliBinary, f.Flags())
+	res, errStr := tests.ExecuteT(f.T, cmd, "")
+	require.Empty(f.T, errStr)
+
+	var params slashing.Params
+	err := f.Cdc.UnmarshalJSON([]byte(res), &params)
+	require.NoError(f.T, err)
+	return params
+}