Test that generate_test_code.py is still compatible with Python 2

When Mbed TLS 2.16 was released, the requirement was Python 2, not
Python 3. Since then, upstream Python 2 support has stopped, but it is
still maintained in some long-term-support distributions. For the sake
of users who build the unit tests in such environments, test that
generate_test_code.py remains compatible with Python 2.

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

tests/Makefile

@@ -62,7 +62,7 @@ BINARIES := $(addsuffix $(EXEXT),$(APPS))
 
 .SILENT:
 
-.PHONY: all check test clean
+.PHONY: all c_files check test clean
 
 all: $(BINARIES)
 
@@ -70,6 +70,7 @@ $(DEP):
 	$(MAKE) -C ../library
 
 C_FILES := $(addsuffix .c,$(APPS))
+c_files: $(C_FILES)
 
 # Wildcard target for test code generation:
 # A .c file is generated for each .data file in the suites/ directory. Each .c

tests/scripts/all.sh

@@ -691,6 +691,18 @@ component_check_doxygen_warnings () {
     record_status tests/scripts/doxygen.sh
 }
 
+component_check_python2 () {
+    # Check that what used to work with Python 2 still works with Python 2.
+    msg "check: python2 compatibility"
+    mkdir -p tests/with_python2 tests/with_python3
+    make -C tests PYTHON=python2 c_files
+    mv tests/test_suite_*.c tests/with_python2/
+    make -C tests PYTHON=python3 c_files
+    mv tests/test_suite_*.c tests/with_python3/
+    diff -r tests/with_python2 tests/with_python3
+    rm -rf tests/with_python2 tests/with_python3
+}
+
 
 
 ################################################################

tests/scripts/generate_test_code.py

@@ -1,4 +1,7 @@
 #!/usr/bin/env python3
+
+# This script should still be compatible with Python 2 in Mbed TLS 2.16.x.
+
 # Test suites code generator.
 #
 # Copyright The Mbed TLS Contributors