It's alive! CustomizeDiff logic now has been inserted into the diff
process. The test_resource_with_custom_diff resource provides some basic
testing and a reference implementation.
There should now be plenty of test coverage for this feature via the
tests added for ResourceDiff, and the basic test added to the
schemaMap.Diff test, and the test resource, but more can be added to
test any specific case that comes up otherwise.
It turns out that `d.GetOk` also returns `false` when the user _did_ actually supply a value for it in the config, but the value itself needs to be evaluated before it can be used.
So instead of passing a `ResourceData` we now pass a `ResourceConfig`
which makes much more sense for doing the validation anyway.
The tests did pass, but that was because they only tested part of the changes. By using the `schema.TestResourceDataRaw` function the schema and config are better tested and so they pointed out a problem with the schema of the Chef provisioner.
The `Elem` fields did not have a `*schema.Schema` but a `schema.Schema` and in an `Elem` schema only the `Type` field may (and must) be set. Any other fields like `Optional` are not allowed here.
Next to fixing that problem I also did a little refactoring and cleaning up. Mainly making the `ProvisionerS` private (`provisioner`) and removing the deprecated fields.
1. Migrate `chef` provisioner to `schema.Provisioner`:
* `chef.Provisioner` structure was renamed to `ProvisionerS`and now it's decoded from `schema.ResourceData` instead of `terraform.ResourceConfig` using simple copy-paste-based solution;
* Added simple schema without any validation yet.
2. Support `ValidateFunc` validate function : implemented in `file` and `chef` provisioners.
Chris Marchesi