Add entries in exclude_patterns.

doc/source/conf.py

@@ -64,7 +64,7 @@
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
 # This pattern also affects html_static_path and html_extra_path.
-exclude_patterns = []
+exclude_patterns = ['_build', '**/tests/*']
 
 # Extension configuration