Add lint_main_returns.

lint_main_returns.py

@@ -0,0 +1,45 @@
+'''
+lint_argparse_returns
+=====================
+'''
+import ast
+import argparse
+import sys
+
+from voussoirkit import pathclass
+from voussoirkit import vlogging
+
+log = vlogging.getLogger(__name__, 'lint_argparse_returns')
+
+@vlogging.main_decorator
+def main(argv):
+    return_status = 0
+
+    files = pathclass.glob('*.py')
+    files = (f for f in files if f.is_file)
+    for file in files:
+        no_py = file.replace_extension('').basename
+        text = file.open('r', encoding='utf-8').read()
+        try:
+            tree = ast.parse(text)
+        except Exception:
+            log.error('%s failed to parse.', file.absolute_path)
+            return_status = 1
+            continue
+        functions = [f for f in tree.body if isinstance(f, ast.FunctionDef)]
+        functions = [f for f in functions if f.name.endswith('_argparse') or f.name == 'main']
+        for function in functions:
+            returns = [node for node in ast.walk(function) if isinstance(node, ast.Return)]
+
+            if not returns:
+                log.warning('%s.%s has no return.', no_py, function.name)
+                return_status = 1
+
+            for ret in returns:
+                source = ast.get_source_segment(text, ret.value)
+                log.info('%s.%s returns %s.', no_py, function.name, source)
+
+    return return_status
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))