Refactor metadata handling

sphinx/environment/collectors/metadata.py

@@ -9,6 +9,8 @@
     :license: BSD, see LICENSE for details.
 """
 
+from typing import List, cast
+
 from docutils import nodes
 
 from sphinx.environment.collectors import EnvironmentCollector
@@ -52,12 +54,18 @@ class MetadataCollector(EnvironmentCollector):
         for node in docinfo:
             # nodes are multiply inherited...
             if isinstance(node, nodes.authors):
-                md['authors'] = [author.astext() for author in node]
-            elif isinstance(node, nodes.TextElement):  # e.g. author
-                md[node.__class__.__name__] = node.astext()
+                authors = cast(List[nodes.author], node)
+                md['authors'] = [author.astext() for author in authors]
+            elif isinstance(node, nodes.field):
+                assert len(node) == 2
+                field_name = cast(nodes.field_name, node[0])
+                field_body = cast(nodes.field_body, node[1])
+                md[field_name.astext()] = field_body.astext()
             else:
-                name, body = node
-                md[name.astext()] = body.astext()
+                # other children must be TextElement
+                # see: http://docutils.sourceforge.net/docs/ref/doctree.html#bibliographic-elements  # NOQA
+                element = cast(nodes.TextElement, node)
+                md[element.__class__.__name__] = element.astext()
         for name, value in md.items():
             if name in ('tocdepth',):
                 try:

tests/roots/test-metadata/conf.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+master_doc = 'index'

tests/roots/test-metadata/index.rst

@@ -42,16 +42,5 @@
        markup language, containing examples of all basic
        constructs and many advanced constructs.
 
-================================
- reStructuredText Demonstration
-================================
-
-.. Above is the document title, and below is the subtitle.
-   They are transformed from section titles after parsing.
-
---------------------------------
- Examples of Syntax Constructs
---------------------------------
-
-.. bibliographic fields (which also require a transform):
-
+test-metadata
+==============

tests/roots/test-root/index.txt

@@ -23,7 +23,6 @@ Contents:
    bom
    math
    autodoc
-   metadata
    extensions
    extensions
    footnote

tests/test_metadata.py

@@ -15,7 +15,7 @@
 import pytest
 
 
-@pytest.mark.sphinx('pseudoxml')
+@pytest.mark.sphinx('dummy', testroot='metadata')
 def test_docinfo(app, status, warning):
     """
     Inspect the 'docinfo' metadata stored in the first node of the document.
@@ -24,9 +24,7 @@ def test_docinfo(app, status, warning):
     'dedication' blocks, or the 'meta' role. Doing otherwise is probably more
     messing with the internals of sphinx than this rare use case merits.
     """
-    app.builder.build(['metadata'])
-    env = app.env
-    exampledocinfo = env.metadata['metadata']
+    app.build()
     expecteddocinfo = {
         'author': u'David Goodger',
         'authors': [u'Me', u'Myself', u'I'],
@@ -51,4 +49,4 @@ def test_docinfo(app, status, warning):
         'orphan': u'',
         'nocomments': u'',
     }
-    assert exampledocinfo == expecteddocinfo
+    assert app.env.metadata['index'] == expecteddocinfo