Issue 4687 - Add Context Function get_pages_metadata to Test Site

tests/test_site/globals/get_pages_metadata.py

+import re
+from jinja2 import contextfunction
+
+
+@contextfunction
+def get_pages_metadata(context, filters=None):
+    if not isinstance(filters, dict) and filters:
+        raise TypeError('Filters are not a dictionary')
+
+    return_data = []
+    for page_name, _format in context['source'].list_pages():
+        data, filename = context['source'].read_page(page_name, _format)
+        page_data = parse_page_metadata(data, page_name)
+
+        if filter_metadata(filters, page_data) is True:
+            return_data.append(page_data)
+
+    return return_data
+
+
+def parse_page_metadata(data, page):
+    page_metadata = {'page': page}
+    lines = data.splitlines(True)
+    for i, line in enumerate(lines):
+        if not re.search(r'^\s*[\w\-]+\s*=', line):
+            break
+        name, value = line.split('=', 1)
+        value = value.strip()
+        if value.startswith('[') and value.endswith(']'):
+            value = [element.strip() for element in value[1:-1].split(',')]
+        page_metadata[name.strip()] = value
+    return page_metadata
+
+
+def filter_metadata(filters, metadata):
+    if filters is None:
+        return True
+    for filter_name, filter_value in filters.items():
+        if filter_name not in metadata:
+            return False
+        for option in filter_value.split(','):

[Vasily Kuznetsov, 2017/03/10 10:23:38]

We should probably only split if the `metadata[filter_name]` is a list.
Otherwise if we have a date field and want to match by it, it won't work.

[Jon Sonesen, 2017/03/10 11:01:32]

I guess I thought that this didnt matter since julian said they wont need dates
or any strings with commas inside the config fields. However I understand what
you mean here as once we move to json compatibility this will be a concern, I
will address this.

[Jon Sonesen, 2017/03/10 11:43:38]

Actually in this case we will have to change the filter syntax to just accept
json as well, this way you can filter on values which have commas currently it
is like this filter={'tags':'popular, bar'} which is nice and simple but also
lacks the robust-yness required to filter based on values once we add json
support. 

[Vasily Kuznetsov, 2017/03/15 18:02:57]

Yeah, this is better. Splitting the filter values was error-prone.

+            if isinstance(metadata[filter_name], list):
+                if option not in metadata[filter_name]:
+                    return False
+                return True

[Vasily Kuznetsov, 2017/03/10 10:23:38]

But if you return `True` here, would not this ignore the following filters?

[Jon Sonesen, 2017/03/10 11:01:32]

I thought we were doing an 'or' selection so if one of the values matches the
page is added. If this is wrong I will change it.

[Vasily Kuznetsov, 2017/03/15 18:02:57]

Yes, the docstring of the function in the issue says "A list of metadata dicts
for pages matching all the filters". BTW, perhaps it makes sense to include the
docstring into the patch here as well.

+            if option != metadata[filter_name]:
+                return False
+    return True