Apollo Client 3.10 has been released, introducing new experimental schema-based testing utilities under the `@apollo/client/testing/experimental` import. The new tools, `createTestSchema` and `createSchemaFetch`, allow for more flexible and realistic testing of GraphQL schemas. Additionally, a new API called `client.watchFragment` enables the functionality of the `useFragment` hook to be used in Vanilla JavaScript or other frameworks. Furthermore, the `createQueryPreloader` API has reached "stable" status after being introduced as "alpha" in Apollo Client 3.9 and hearing positive feedback from users. The new features are designed to provide a more comprehensive testing experience for developers using Apollo Client.