Using drupalPostForm to test entities made with ECK doesn't call hook_entity_update or hook_entity_insert

Problem/Motivation

I am writing tests that create custom ECK entities using drupalPostForm and they do not fire the expected hook_entity_* hooks.

Proposed resolution

Make it so using drupalPostForm to create eck entities it doesn't bypass hook_entity_* hooks.

steps to reproduce

1. Create custom entity type/bundle with ECK
2. Create custom module that implements both hook_entity_create and hook_entity_insert
3. Add breakpoint or dpm call to the hook_entity_* implementations.
4. Add a test which uses drupalPostForm on route eck.entity.add and notice that the hook implementations are never called.