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.
By prefixing them with `cmd /c` it will work with both `winner` and
`ssh` connection types.
This PR also reverts some bad stringer changes made in PR #2673
Before this option (`os_type`) the provisioner would use the connection
type to determine the targeted OS. When not supplying a value for
`os_type`, it will fall back to the old behaviour, so this is full BC.
Sander van Harmelen