Check doctest files

They are converted to python files before running checks.

.gitlab-scripts/doctest2python.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+
+import doctest
+import glob
+import os
+from itertools import chain
+from pathlib import Path
+
+ROOT_DIR = os.path.dirname(os.path.dirname(__file__))
+
+if __name__ == '__main__':
+    parser = doctest.DocTestParser()
+
+    for filename in chain(glob.glob('**/*/tests/*.rst', root_dir=ROOT_DIR)):
+        filename = Path(filename)
+        with open(filename, 'r') as scenario:
+            text = scenario.read()
+
+        with open(filename.with_suffix('.py'), 'w') as file:
+            newline = False
+            for line in parser.parse(text):
+                if isinstance(line, doctest.Example):
+                    if newline:
+                        file.write('\n')
+                    file.write(line.source)
+                    newline = False
+                elif not line:
+                    pass
+                else:
+                    newline = True