client/mock: add new tests

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

client/mock/proto/github.pb.go

@@ -0,0 +1,19 @@
+package pb
+
+import (
+	_ "go.unistack.org/micro-proto/v3/api"
+	_ "go.unistack.org/micro-proto/v3/openapiv3"
+)
+
+type LookupUserReq struct {
+	Username string `json:"username,omitempty"`
+}
+
+type LookupUserRsp struct {
+	Name string `json:"name,omitempty"`
+}
+
+type Error struct {
+	Message          string `json:"message,omitempty"`
+	DocumentationUrl string `json:"documentation_url,omitempty"`
+}