tests/extmod: Improve test coverage of ure module.

tests/extmod/ure1.py

@@ -11,6 +11,10 @@ try:
 except IndexError:
     print("IndexError")
 
+# conversion of re and match to string
+str(r)
+str(m)
+
 r = re.compile("(.+)1")
 m = r.match("xyz781")
 print(m.group(0))

tests/extmod/ure_split_notimpl.py

+import ure as re
+
+r = re.compile('( )')
+try:
+    s = r.split("a b c foobar")
+except NotImplementedError:
+    print('NotImplementedError')

tests/extmod/ure_split_notimpl.py.exp

+NotImplementedError