How to use

stubTrue

function

in

LoDashStatic

function collOf(predicate, options = {}) {
  const {kind = _.stubTrue, distinct = false, into} = options;
  const uniq = value => !distinct || isUnique(value);

  return {
    conform: value => {
      const result = kind(value) && uniq(value) && checkCount(value, options)
         && _.every(value, v => isValid(predicate, v));
      return result ? transform(value, into) : invalidString;
    },
    unform: _.identity,
    gen: () => tcg.null.then(() => tcg.array(gen(predicate), {size: options.count})),
    describe: () => [collOf.name, ...describe([predicate]), ...describe(_.flatten(_.toPairs(options)))],
    explain: function*(values, {via}) {
      yield* explainCount(values, options, via);
      yield* explainInvalid(values, predicate, via);
    }
  };
}

function fspec(options) {
  const {args: argsSpec, ret, fn} = options;

  const funcSpec = fn ? fn : _.stubTrue;

  return {
    conform: f => {
      if (isFunction(f)) {
        // TODO: Overlap with test/check.js!!!
        const samples = exercise(argsSpec, 10);

        const validReturnValue = ([, returnValue]) => isValid(ret, returnValue);
        const validateFunction = ([args, returnValue]) => funcSpec({ret: returnValue, args: conform(argsSpec, args)});

        const results = _.map(samples, ([args]) => [args, f(...args)]);

        const pass = _.every(results, sample => validReturnValue(sample) && validateFunction(sample));

        return pass ? f : invalidString;
      } else {
        return invalidString;
      }
    }
  };
}