More precise name for test data generation

We have Python code both for test code generation
(tests/scripts/generate_test_code.py) and now for test data generation.
Avoid the ambiguous expression "test generation".

This commit renames the Python module and adjusts all references to it. A
subsequent commit will adjust the documentation.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/generate_bignum_tests.py b/tests/scripts/generate_bignum_tests.py
index ceafa4a..1cd859c 100755
--- a/tests/scripts/generate_bignum_tests.py
+++ b/tests/scripts/generate_bignum_tests.py
@@ -6,7 +6,7 @@
 
 Class structure:
 
-Child classes of test_generation.BaseTarget (file targets) represent an output
+Child classes of test_data_generation.BaseTarget (file targets) represent an output
 file. These indicate where test cases will be written to, for all subclasses of
 this target. Multiple file targets should not reuse a `target_basename`.
 
@@ -36,7 +36,7 @@
         call `.create_test_case()` to yield the TestCase.
 
 Additional details and other attributes/methods are given in the documentation
-of BaseTarget in test_generation.py.
+of BaseTarget in test_data_generation.py.
 """
 
 # Copyright The Mbed TLS Contributors
@@ -63,7 +63,7 @@
 
 import scripts_path # pylint: disable=unused-import
 from mbedtls_dev import test_case
-from mbedtls_dev import test_generation
+from mbedtls_dev import test_data_generation
 
 T = TypeVar('T') #pylint: disable=invalid-name
 
@@ -85,7 +85,7 @@
     )
 
 
-class BignumTarget(test_generation.BaseTarget, metaclass=ABCMeta):
+class BignumTarget(test_data_generation.BaseTarget, metaclass=ABCMeta):
     #pylint: disable=abstract-method
     """Target for bignum (mpi) test case generation."""
     target_basename = 'test_suite_mpi.generated'
@@ -235,4 +235,4 @@
 
 if __name__ == '__main__':
     # Use the section of the docstring relevant to the CLI as description
-    test_generation.main(sys.argv[1:], "\n".join(__doc__.splitlines()[:4]))
+    test_data_generation.main(sys.argv[1:], "\n".join(__doc__.splitlines()[:4]))