client: add GetOraclePrice for oracle price

pkg/rpc/client/native.go

@@ -0,0 +1,18 @@
+package client
+
+// Various non-policy things from native contracs.
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
+)
+
+// GetOraclePrice invokes `getPrice` method on a native Oracle contract.
+func (c *Client) GetOraclePrice() (int64, error) {
+	oracleHash, err := c.GetNativeContractHash(nativenames.Notary)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get native Oracle hash: %w", err)
+	}
+	return c.invokeNativeGetMethod(oracleHash, "getPrice")
+}

pkg/rpc/client/rpc_test.go

@@ -440,6 +440,18 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getOraclePrice": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetOraclePrice()
+			},
+			serverResponse: `{"id":1,"jsonrpc":"2.0","result":{"state":"HALT","gasconsumed":"2007390","script":"EMAMDWdldEZlZVBlckJ5dGUMFJphpG7sl7iTBtfOgfFbRiCR0AkyQWJ9W1I=","stack":[{"type":"Integer","value":"10000000"}],"tx":null}}`,
+			result: func(c *Client) interface{} {
+				return int64(10000000)
+			},
+		},
+	},
 	"getMaxNotValidBeforeDelta": {
 		{
 			name: "positive",