Update TESTING info

docs/TESTING.md

+
 ## Testing
 
-**JSON-Schema-Faker** has performs two types of testing: unit and schema.
+**JSON-Schema-Faker** performs two types of testing: unit and schema.
 
 ### Unit tests
 
 - They just validate the building blocks from the entire library
 - We're using `mocha` and `chai` so the worflow would be very familiar
 
+> Much stuff from the internals are not covered by unit-tests yet, PRs for increasing that are very welcome!
+
 ----
 
 ### Schema tests
@@ -49,15 +52,16 @@ The properties below are used to setup the test and execute the assertions:
 - `refs` — are for resolving used `$ref`'s on the faked schema
 - `throws` — test if the an error was expected, can be a boolean or string
 - `hasNot` — used for primitives, it will perform a `not.toContain()` test
-- `hasProps` —
-- `onlyProps` —
+- `hasProps` — ensure given props exists on the generated value
+- `onlyProps` — ensure given props matches the generated value
 - `type` — used for primitives, it will perform a `toHaveType()` test
 - `valid` — will test the generated json against the original schema
 - `equal` — will test equality for the given schema and the generated one
 - `repeat` — will execute the same test many times as given
-- `seed` —
-- `set` —
-- `skip` —
-- `only` —
-- `count` —
-- `length` —
+- `seed` — provide the given seed to the `random()` generator
+- `count` — will match arrays/strings length or object props, etc.
+- `set` — configure given options through `jsf.option()`
+- `skip` — skip individual tests
+- `only` — run this test only
+
+> Use these tests as reference of how things works, if you found an edge-case please add it as test and open an issue for.