rn-fetch-blob/test/react-native-testkit/lib/comparer.js

export default {
  greater : (a, b) => a > b,
  smaller : (a, b) => a < b,
  instanceOf : (a, b) => a instanceof b,
  typeof : (a, b) => typeof a === b,
  IsNull : (a, b) => a === null,
  exists : (a, b) => a !== void 0,
  hasValue : (a, b) => (a !== void 0) && (Array.isArray(a) ? a.length !==0 : true),
  isArray : (a, b) => Array.isArray(a),
}