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
+        if isinstance(metadata[filter_name], list):
+            for option in filter_value:

[Vasily Kuznetsov, 2017/03/15 18:02:58]

How about the situation when the field is a list but the filter value is a
string? For example if tags=[foo, bar] and filters={'tags': 'foo'}. I would say
the page should be included but when it iterates over 'foo' (as opposed to
['foo']), it will not find 'f' in ['foo', 'bar'] and so False will be returned.

If you agree that get_pages_metadata(filters={'tags': 'foo'}) should return a
page with tags=[foo, bar] in the header, perhaps the solution here would be to
check if `filter_value` is an instance of `basestring` and convert it to a
one-item list in this case.

[Jon Sonesen, 2017/03/17 07:53:33]

Odd, I thought I had actually changed this. But perhaps it was in a shelved
change that i forgot about. Either way yes I agree that there should be handling
for the ase that the filter is just a single string value.

Thanks for bringing this up.

+                if str(option) not in metadata[filter_name]:
+                    return False
+        if filter_value != metadata[filter_name]:

[Vasily Kuznetsov, 2017/03/15 18:02:58]

Should not this be `elif` instead of `if`. It seems like executing this for
listy fields would create false negatives. For example if we have a page that
has tags=[foo, bar] and then we do a search with the filters={'tags': ['bar',
'foo']}, this branch would trigger and return False (and I don't think it makes
sense to make tags order-dependent).

[Jon Sonesen, 2017/03/17 07:53:33]

Oh yeah, that is a good catch.

+                return False
+    return True