- [new] `mount`: `.state()`/`.setState()`: allow calling on children (#1802)
- [new] `configuration`: add `reset`
- [fix] `makeOptions`: ensure that config-level `attachTo`/`hydrateIn` are inherited into wrapper options (#1836)
- [fix] `shallow`/`Utils`: call into adapter’s `isCustomComponentElement` if present (#1832)
- [fix] `shallow`/`mount`: throw an explicit error when state is null/undefined
- [fix] freeze ROOT_NODES for child wrappers (#1811)
- [fix] `shallow`: `.parents`: ensure that one `.find` call does not affect another (#1781)
- [fix] `mount`: update after `simulateError` (#1812)
- [refactor] `mount`/`shallow`: `getElement`: use `this.single`
- [deps] update `babel-preset-airbnb`, `chai`, `eslint`, `mocha`, `enzyme-adapter-utils`, `react-is`, `airbnb-js-shims`
