Move some testing helpers into a module

Might be a little less setup? Something like (maybe need to split up or move arguments around): Basically always unpad, trim

const babel = require("babel-core");
const unpad = require("utils/unpad");

export function transform(source, plugin, options) {
  return babel.transform(unpad(source),  {
    plugins: [[plugin, options]],
  }).code.trim();
}

export function expectTransform(source, expected, plugin, options = {}) {
  return expect(transform(source, plugin, options)).toBe(unpad(expected));
}

[cpojer]

Jest snapshots work with any serializable value, we just haven’t documented it yet. This is actually the ideal use case for snapshots and should allow you guys to move much faster. Also cc @kyldvs who loves using it for strings.

[boopathi]

Added in #606 . 😃