Replace recipes_test.py with a new parallel expectation-based test runner.

scripts/slave/README.recipes.md

 Recipes
 =======
 Recipes are a flexible way to specify How to Do Things, without knowing too much
 about those Things.
 
 
 Anecdote
 --------
 In the before-times, circa 2003, there was a quaint build system called BuildBot.
 BuildBot had many, many features, and was written to encapsulate every aspect of
@@ skipping 324 matching lines @@
     data>}`. See module docstrings to see what they accept for mocks.
   * *step_mocks*: This is a dictionary which defines the mock data for
     various `recipe_api.Placeholder` objects. These are explained more in
     a later section.  This dictionary is in the form of `{<step name>: {<mod
     name>: <mod data>}}`
     * There is one 'special' mod name, which is '$R'. This module refers to the
       return code of the step, and takes an integer. If it is missing, it is
       assumed that the step succeeded with a retcode of 0.
 
 The `api` passed to GenTests is confusingly **NOT** the same as the recipe api.
-It's actually an instance of `unittests/recipes_test.py:TestApi()`. This is
+It's actually an instance of `recipe_test_api.py:RecipeTestApi()`. This is
 adimittedly pretty weak, and it would be great to have the test api
 automatically created via modules. On the flip side, the test api is much less
 necessary than the recipe api, so this transformation has not been designed yet.
 
 
 What is that config business?
 -----------------------------
 **Configs are a way for a module to expose it's "global" state in a reusable
 way.**
 
@@ skipping 249 matching lines @@
 of the json module to see how this is implemented.
 
 
 How do I know what modules to use?
 ----------------------------------
 Use `tools/show_me_the_modules.py`. It's super effective!
 
 
 How do I run those tests you were talking about?
 ------------------------------------------------
-To test all the recipes/apis, use `slave/unittests/recipes_test.py`. To set new
-expectations `slave/unittests/recipes_test.py --train`.
+To test all the recipes/apis, use `slave/unittests/recipe_simulation_test.py`.
+To set new expectations `slave/unittests/recipe_simulation_test.py train`.
 
-To test all the configs, use `slave/unittests/recipe_configs_test.py`. To set
-new expectations `slave/unittests/recipe_configs_test.py --train`.
 
 
 Where's the docs on `*.py`?
 --------------------------------------------
 Check the docstrings in `*.py`. `<trollface text="Problem?"/>`
 
 In addition, most recipe modules have an `example.py` file which exercises most
 of the code in the module for both test coverage and example purposes.
 
 If you want to know what keys a step dictionary can take, take a look at
 `common/annotator.py`.