Add XOF to test_suite_psa_crypto_driver_wrappers

[gilles-peskine-arm]

Mbed-TLS/mbedtls-framework#265 added a test driver for XOF, and #683 added the corresponding PSA API including driver dispatch. But we are missing tests for the XOF dispatch in test_suite_psa_crypto_driver_wrappers.

The goal of this issue is to add the missing test function and test cases.

[minosgalanakis]

While reviewering #773 I came to wonder what the definition of done is for this issue.

Are we looking to just just the common specanio of a dispatch or are we aiming to add coverage for all the methods exposed by the driver? That means we need to test code-paths for:

• mbedtls_psa_xof_set_context
• psa_xof_output
• psa_xof_update
• psa_xof_abort

Given the size of the issue I assume it means to cover the basic driver dispatch, but wanted to confirm.

[gilles-peskine-arm]

Similar to what we have for hashes (except that there's no one-shot interface for XOF, only the multipart interface):

• Assert that the driver was called (via the number of hits) when there's a driver, in normal operation. This is done separately for each function.
• Assert that the driver is not called if there's an error that the core should detect (e.g. bad state, or failed setup).

There's a fairly large amount of code, but it follows a simple model and can be mostly copy-pasted from the hash code with a change of function names.