error: Self type should not change between runtime apis
  --> $DIR/mock_only_one_self_type.rs:19:23
   |
19 |     impl Api2<Block> for MockApi2 {
   |                          ^^^^^^^^

error: First self type found here
  --> $DIR/mock_only_one_self_type.rs:15:22
   |
15 |     impl Api<Block> for MockApi {
   |                         ^^^^^^^
