graphql / graphql-js / 647

99%

master: 98%

push

travis-ci

[Schema] Implementing interfaces with covariant return types.

This proposes loosening the definition of implementing an interface by allowing an implementing field to return a subtype of the interface field's return type.

This example would previously be an illegal schema, but become legal after this diff:

```graphql
interface Friendly {
  bestFriend: Friendly
}

type Person implements Friendly {
  bestFriend: Person
}
```

56 of 56 new or added lines in 4 files covered. (100.0%)

5461 of 5492 relevant lines covered (99.44%)

1437.02 hits per line