diff --git a/scripts/mbedtls_dev/test_generation.py b/scripts/mbedtls_dev/test_generation.py
index b825df07b..aeb551d05 100644
--- a/scripts/mbedtls_dev/test_generation.py
+++ b/scripts/mbedtls_dev/test_generation.py
@@ -25,7 +25,7 @@ import posixpath
 import re
 
 from abc import ABCMeta, abstractmethod
-from typing import Callable, Dict, Iterable, List, Type, TypeVar
+from typing import Callable, Dict, Iterable, Iterator, List, Type, TypeVar
 
 from mbedtls_dev import build_tree
 from mbedtls_dev import test_case
@@ -91,16 +91,31 @@ class BaseTarget(metaclass=ABCMeta):
         return tc
 
     @classmethod
-    def generate_tests(cls):
-        """Generate test cases for the target subclasses.
+    @abstractmethod
+    def generate_function_tests(cls) -> Iterator[test_case.TestCase]:
+        """Generate test cases for the test function.
 
-        During generation, each class will iterate over any subclasses, calling
-        this method in each.
-        In abstract classes, no tests will be generated, as there is no
-        function to generate tests for.
-        In classes which do implement a test function, this should be overridden
-        and a means to use `create_test_case()` should be added.
+        This will be called in classes where `test_function` is set.
+        Implementations should yield TestCase objects, by creating instances
+        of the class with appropriate input data, and then calling
+        `create_test_case()` on each.
         """
+        pass
+
+    @classmethod
+    def generate_tests(cls) -> Iterator[test_case.TestCase]:
+        """Generate test cases for the class and its subclasses.
+
+        In classes with `test_function` set, `generate_function_tests()` is
+        used to generate test cases first.
+        In all classes, this method will iterate over its subclasses, and
+        yield from `generate_tests()` in each.
+
+        Calling this method on a class X will yield test cases from all classes
+        derived from X.
+        """
+        if cls.test_function:
+            yield from cls.generate_function_tests()
         for subclass in sorted(cls.__subclasses__(), key=lambda c: c.__name__):
             yield from subclass.generate_tests()
 
diff --git a/tests/scripts/generate_bignum_tests.py b/tests/scripts/generate_bignum_tests.py
index 3f556ce29..1f6448528 100755
--- a/tests/scripts/generate_bignum_tests.py
+++ b/tests/scripts/generate_bignum_tests.py
@@ -160,14 +160,10 @@ class BignumOperation(BignumTarget, metaclass=ABCMeta):
         yield from cls.input_cases
 
     @classmethod
-    def generate_tests(cls) -> Iterator[test_case.TestCase]:
-        if cls.test_function:
-            # Generate tests for the current class
-            for l_value, r_value in cls.get_value_pairs():
-                cur_op = cls(l_value, r_value)
-                yield cur_op.create_test_case()
-        # Once current class completed, check descendants
-        yield from super().generate_tests()
+    def generate_function_tests(cls) -> Iterator[test_case.TestCase]:
+        for l_value, r_value in cls.get_value_pairs():
+            cur_op = cls(l_value, r_value)
+            yield cur_op.create_test_case()
 
 
 class BignumCmp(BignumOperation):