Generate config test cases for single options

Generate option-on and option-off cases for test_suite_config, for all
boolean options (MBEDTLS_xxx and PSA_WANT_xxx, collected from the mbedtls
and PSA config files).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/generate_config_tests.py

@@ -0,0 +1,96 @@
+#!/usr/bin/env python3
+"""Generate test data for configuration reporting.
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+
+import re
+import sys
+from typing import Iterable, Iterator, List, Optional, Tuple
+
+import project_scripts # pylint: disable=unused-import
+import config
+from mbedtls_framework import test_case
+from mbedtls_framework import test_data_generation
+
+
+def single_option_case(setting: config.Setting, when_on: bool,
+                       dependencies: List[str],
+                       note: Optional[str]) -> test_case.TestCase:
+    """Construct a test case for a boolean setting.
+
+    This test case passes if the setting and its dependencies are enabled,
+    and is skipped otherwise.
+
+    * setting: the setting to be tested.
+    * when_on: True to test with the setting enabled, or False to test
+      with the setting disabled.
+    * dependencies: extra dependencies for the test case.
+    * note: a note to add after the option name in the test description.
+      This is generally a summary of dependencies, and is generally empty
+      if the given setting is only tested once.
+    """
+    base = setting.name if when_on else '!' + setting.name
+    tc = test_case.TestCase()
+    tc.set_function('pass')
+    description_suffix = ' (' + note + ')' if note else ''
+    tc.set_description('Config: ' + base + description_suffix)
+    tc.set_dependencies([base] + dependencies)
+    return tc
+
+
+def conditions_for_option(cfg: config.Config,
+                          setting: config.Setting
+                          ) -> Iterator[Tuple[List[str], str]]:
+    """Enumerate the conditions under which to test the given setting.
+
+    * cfg: all configuration options.
+    * setting: the setting to be tested.
+
+    Generate a stream of conditions, i.e. extra dependencies to test with
+    together with a human-readable explanation of each dependency. Some
+    typical cases:
+
+    * By default, generate a one-element stream with no extra dependencies.
+    * If the setting is ignored unless some other option is enabled, generate
+      a one-element stream with that other option as an extra dependency.
+    * If the setting is known to interact with some other option, generate
+      a stream with one element where this option is on and one where it's off.
+    * To skip the setting altogether, generate an empty stream.
+    """
+    name = setting.name
+    if name.endswith('_ALT') and not config.is_seamless_alt(name):
+        # We don't test alt implementations, except (most) platform alts
+        return
+    yield [], ''
+
+
+def enumerate_boolean_option_cases(cfg: config.Config
+                                   ) -> Iterable[test_case.TestCase]:
+    """Emit test cases for all boolean options."""
+    for name in sorted(cfg.settings.keys()):
+        setting = cfg.settings[name]
+        if not name.startswith('PSA_WANT_') and setting.value:
+            continue # non-boolean setting
+        for when_on in True, False:
+            for deps, note in conditions_for_option(cfg, setting):
+                yield single_option_case(setting, when_on, deps, note)
+
+
+
+class ConfigTestGenerator(test_data_generation.TestGenerator):
+    """Generate test cases for configuration reporting."""
+
+    def __init__(self, options):
+        self.mbedtls_config = config.ConfigFile()
+        self.targets['test_suite_config.mbedtls_boolean'] = \
+            lambda: enumerate_boolean_option_cases(self.mbedtls_config)
+        self.psa_config = config.ConfigFile('include/psa/crypto_config.h')
+        self.targets['test_suite_config.psa_boolean'] = \
+            lambda: enumerate_boolean_option_cases(self.psa_config)
+        super().__init__(options)
+
+
+if __name__ == '__main__':
+    test_data_generation.main(sys.argv[1:], __doc__, ConfigTestGenerator)