Break up the god class TestGenerator

Use separate classes for information gathering, for each kind of test
generation (currently just one: not-supported), and for writing output
files.

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

tests/scripts/generate_psa_tests.py

@@ -69,41 +69,13 @@ def hack_dependencies_not_implemented(dependencies: List[str]) -> None:
                for dep in dependencies):
         dependencies.append('DEPENDENCY_NOT_IMPLEMENTED_YET')
 
-def test_case_for_key_type_not_supported(
-        verb: str, key_type: str, bits: int,
-        dependencies: List[str],
-        *args: str,
-        param_descr: str = ''
-) -> test_case.TestCase:
-    """Return one test case exercising a key creation method
-    for an unsupported key type or size.
-    """
-    hack_dependencies_not_implemented(dependencies)
-    tc = test_case.TestCase()
-    short_key_type = re.sub(r'PSA_(KEY_TYPE|ECC_FAMILY)_', r'', key_type)
-    adverb = 'not' if dependencies else 'never'
-    if param_descr:
-        adverb = param_descr + ' ' + adverb
-    tc.set_description('PSA {} {} {}-bit {} supported'
-                       .format(verb, short_key_type, bits, adverb))
-    tc.set_dependencies(dependencies)
-    tc.set_function(verb + '_not_supported')
-    tc.set_arguments([key_type] + list(args))
-    return tc
 
-class TestGenerator:
-    """Gather information and generate test data."""
+class Information:
+    """Gather information about PSA constructors."""
 
-    def __init__(self, options):
-        self.test_suite_directory = self.get_option(options, 'directory',
-                                                    'tests/suites')
+    def __init__(self) -> None:
         self.constructors = self.read_psa_interface()
 
-    @staticmethod
-    def get_option(options, name: str, default: T) -> T:
-        value = getattr(options, name, None)
-        return default if value is None else value
-
     @staticmethod
     def remove_unwanted_macros(
             constructors: macro_collector.PSAMacroCollector
@@ -126,14 +98,34 @@ class TestGenerator:
         self.remove_unwanted_macros(constructors)
         return constructors
 
-    def write_test_data_file(self, basename: str,
-                             test_cases: Iterable[test_case.TestCase]) -> None:
-        """Write the test cases to a .data file.
 
-        The output file is ``basename + '.data'`` in the test suite directory.
+def test_case_for_key_type_not_supported(
+        verb: str, key_type: str, bits: int,
+        dependencies: List[str],
+        *args: str,
+        param_descr: str = ''
+) -> test_case.TestCase:
+    """Return one test case exercising a key creation method
+    for an unsupported key type or size.
     """
-        filename = os.path.join(self.test_suite_directory, basename + '.data')
-        test_case.write_data_file(filename, test_cases)
+    hack_dependencies_not_implemented(dependencies)
+    tc = test_case.TestCase()
+    short_key_type = re.sub(r'PSA_(KEY_TYPE|ECC_FAMILY)_', r'', key_type)
+    adverb = 'not' if dependencies else 'never'
+    if param_descr:
+        adverb = param_descr + ' ' + adverb
+    tc.set_description('PSA {} {} {}-bit {} supported'
+                       .format(verb, short_key_type, bits, adverb))
+    tc.set_dependencies(dependencies)
+    tc.set_function(verb + '_not_supported')
+    tc.set_arguments([key_type] + list(args))
+    return tc
+
+class NotSupported:
+    """Generate test cases for when something is not supported."""
+
+    def __init__(self, info: Information) -> None:
+        self.constructors = info.constructors
 
     ALWAYS_SUPPORTED = frozenset([
         'PSA_KEY_TYPE_DERIVE',
@@ -187,7 +179,7 @@ class TestGenerator:
             # To be added: derive
         return test_cases
 
-    def generate_not_supported(self) -> None:
+    def generate_not_supported(self) -> List[test_case.TestCase]:
         """Generate test cases that exercise the creation of keys of unsupported types."""
         test_cases = []
         for key_type in sorted(self.constructors.key_types):
@@ -202,13 +194,37 @@ class TestGenerator:
                     kt, param_descr='type')
                 test_cases += self.test_cases_for_key_type_not_supported(
                     kt, 0, param_descr='curve')
+        return test_cases
+
+
+class TestGenerator:
+    """Generate test data."""
+
+    def __init__(self, options) -> None:
+        self.test_suite_directory = self.get_option(options, 'directory',
+                                                    'tests/suites')
+        self.info = Information()
+
+    @staticmethod
+    def get_option(options, name: str, default: T) -> T:
+        value = getattr(options, name, None)
+        return default if value is None else value
+
+    def write_test_data_file(self, basename: str,
+                             test_cases: Iterable[test_case.TestCase]) -> None:
+        """Write the test cases to a .data file.
+
+        The output file is ``basename + '.data'`` in the test suite directory.
+        """
+        filename = os.path.join(self.test_suite_directory, basename + '.data')
+        test_case.write_data_file(filename, test_cases)
+
+    def generate_all(self) -> None:
+        test_cases = NotSupported(self.info).generate_not_supported()
         self.write_test_data_file(
             'test_suite_psa_crypto_not_supported.generated',
             test_cases)
 
-    def generate_all(self):
-        self.generate_not_supported()
-
 def main(args):
     """Command line entry point."""
     parser = argparse.ArgumentParser(description=__doc__)