Allow tests

[jimbol]

Testing

const sel = composableSelector(getSelectedFooIds)
  .populate(getFooHash)
  .filter(getBaz, (baz, foo = {}) => foo.id === baz.fooId)
  .getEach('name')
  .create();

it('gets the names for each selected foo on baz', () => {
  const obj = { name: 'Jam' };

  sel.test([1])
    .populate({ 1: obj })
    .filter({
      fooId: 1,
    })
    // Skips over static transformers
    .returns(['Jam']);
});

[jimbol]

Instead of a test method on a selector, a separate testComposableSelector function could be exported.

import { testComposableSelector } from 'comp-select';

testComposableSelector(sel, [1])
  .populate({ 1: obj })
  // ...

This is better because we don't have this public method on each selector. Instead, we just have to store the steps (which we store anyway, right?)