async function exportSuite({
  projectDirectory,
  outputDirectory,
  filename,
  runner,
  snippets,
  sharedTargets,
  env,
  options
}) {
  const suite = await readSuite( projectDirectory, filename ),
        gen = new TestGenerator({
          suite,
          schema,
          targets: suite.targets,
          runner,
          projectDirectory,
          outputDirectory,
          snippets,
          sharedTargets,
          env,
          options,
          suiteFilename: filename
        });
  return gen.generate();
}
Export a single suite
@param {String} projectDirectory
@param {String} filename
@param {String} runner
@param {Object} snippets
@param {Object} sharedTargets
@returns {String} - spec.js content