export const tests = []
const t = (f) => tests.push(f)

// obj is declared and of type object
t(() => obj.constructor === Object)

// obj is constant and can not be re-assigned
t(({ fail }) => obj && fail(() => (obj = 10)))

// obj.str is of type string
t(() => typeof obj.str === 'string')

// obj.num is of type number
t(() => typeof obj.num === 'number')

// obj.bool is of type boolean
t(() => typeof obj.bool === 'boolean')

// obj.undef is of type undefined
t(() => 'undef' in obj && typeof obj.undef === 'undefined')

Object.freeze(tests)