function insertFsFixtures(test, fixtures, api) {
  let j = api.jscodeshift;
  let firstBodyNode = test
    .find(j.CallExpression, {callee: {name: 'it'}})
    .find(j.BlockStatement)
    .get('body', 0);
  firstBodyNode.insertBefore(printFsFixture(fixtures));
}
Adds fsFixture declaration expressions to the test.