py/builtinimport: Raise exception on empty module name.

To prevent a crash returning MP_OBJ_NULL.  A test is added for this case.

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/import/builtin_import.py b/tests/import/builtin_import.py
index 088f631fc..157da9839 100644
--- a/tests/import/builtin_import.py
+++ b/tests/import/builtin_import.py
@@ -9,6 +9,12 @@ try:
 except TypeError:
     print('TypeError')
 
+# module name should not be empty
+try:
+    __import__("")
+except ValueError:
+    print('ValueError')
+
 # level argument should be non-negative
 try:
     __import__('xyz', None, None, None, -1)