Be more precise about key pair usage dependencies

Don't always require all of BASIC, IMPORT and EXPORT.

BASIC is always implied by any of the creation methods.

* `KeyTypeNotSupported`: only does an IMPORT (or GENERATE) attempt. EXPORT is
  not needed. This reduces dependencies in
  `test_suite_psa_crypto_not_supported.generated.data`.
* `OpFail`: only does an IMPORT, followed by a BASIC attempt. EXPORT is not
  needed. This reduces dependencies in
  `test_suite_psa_crypto_op_fail.generated.data`.
* `StorageFormat`: only does an IMPORT for save (forward compatibility)
  tests, and only does an EXPORT for read (backward compatibility) tests.
  This reduces dependencies in
  `test_suite_psa_crypto_storage_format.current.data` and
  `test_suite_psa_crypto_storage_format.v0.data` respectively.

Positive test cases that create and exercise a key are still potentially
missing BASIC (which is implied) and EXPORT (which isn't) for exercising the
key, but this is out of scope of this commit.

The generated output has fewer test case dependencies as described above,
with BASIC+IMPORT+EXPORT replaced by only one of IMPORT or EXPORT. Since we
never test partial support for a key type with import or export disabled,
this doesn't change which test cases are executed in each tested
configuration.

Signed-off-by: Gilles Peskine <[email protected]>

scripts/generate_psa_tests.py

@@ -91,7 +91,7 @@ class KeyTypeNotSupported:
                                                           ['GENERATE'])
             import_dependencies = \
                 psa_information.fix_key_pair_dependencies(import_dependencies,
-                                                          ['BASIC', 'IMPORT', 'EXPORT'])
+                                                          ['IMPORT'])
         for bits in kt.sizes_to_test():
             yield test_case_for_key_type_not_supported(
                 'import', kt.expression, bits,
@@ -261,7 +261,7 @@ class OpFail:
                                    ' with ' + pretty_type if pretty_type else ''))
         dependencies = psa_information.automatic_dependencies(alg.base_expression, key_type)
         dependencies = psa_information.fix_key_pair_dependencies(dependencies,
-                                                                 ['BASIC', 'IMPORT', 'EXPORT'])
+                                                                 ['IMPORT'])
         for i, dep in enumerate(dependencies):
             if dep in not_deps:
                 dependencies[i] = '!' + dep
@@ -484,7 +484,7 @@ class StorageFormat:
         tc.add_dependencies(psa_information.generate_deps_from_description(key.description))
         tc.set_function('key_storage_' + verb)
         tc.set_key_bits(key.bits)
-        tc.set_key_pair_usage(['BASIC', 'EXPORT', 'IMPORT'])
+        tc.set_key_pair_usage(['IMPORT'] if self.forward else ['EXPORT'])
         if self.forward:
             extra_arguments = []
         else: