Cooperate with linkcheck builder

Redirect links that direct to an HTTP or HTTPS URL (as opposed to
relative links inside the same website) are now passed to the linkcheck
builder so that it can do its checking work on them.

This necessitates requiring Sphinx >= 7.1 due to a restructuring of the
linkcheck builder code.

Fixes #3

Author: jeanas

docs/rn.rst

@@ -41,4 +41,4 @@ Release notes
 0.0.0 (2020-09-09)
 ******************
 
-Initial release.
+Initial release.

docs/usage.rst

@@ -108,3 +108,16 @@ Occasionally, you have to move complete documentation to a new home. It's easy w
    }
 
 .. tip:: To help search engines to understand the transfer, update (or set) `html_baseurl <https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-html_baseurl>`_ option to the new website, too.
+
+
+Checking your redirects
+***********************
+
+Sphinx has a linkcheck_ builder for finding broken links in your
+documentation.  This extension cooperates with it so that redirects to
+external websites will be checked too.
+
+.. _linkcheck: https://www.sphinx-doc.org/en/master/usage/builders/index.html#sphinx.builders.linkcheck.CheckExternalLinksBuilder
+
+Checking redirects to another page in the same documentation is not
+supported yet.

requirements.txt

@@ -1 +1 @@
-sphinx
+sphinx>=7.1

setup.py

@@ -11,7 +11,7 @@
     long_description=open("README.rst", encoding="utf-8").read(),
     long_description_content_type="text/x-rst",
     packages=["sphinx_reredirects"],
-    install_requires=["sphinx"],
+    install_requires=["sphinx>=7.1"],
     python_requires=">=3.5",
     setup_requires=["wheel"],
     classifiers=[

sphinx_reredirects/__init__.py

@@ -3,8 +3,10 @@
 from pathlib import Path
 from string import Template
 from typing import Dict, Mapping, Optional, Sequence
+from urllib.parse import urlparse
 
 from sphinx.application import Sphinx
+from sphinx.builders.linkcheck import CheckExternalLinksBuilder, Hyperlink
 from sphinx.util import logging
 from sphinx.util.osutil import SEP
 
@@ -28,6 +30,7 @@ def setup(app: Sphinx) -> Dict:
     Extension setup, called by Sphinx
     """
     app.connect("html-collect-pages", init)
+    app.connect("builder-inited", collect_redirects_for_linkcheck)
     app.add_config_value(OPTION_REDIRECTS, OPTION_REDIRECTS_DEFAULT, "env")
     app.add_config_value(OPTION_TEMPLATE_FILE, OPTION_TEMPLATE_FILE_DEFAULT, "env")
     return dict(parallel_read_safe=True)
@@ -162,3 +165,22 @@ def _render_redirect_template(self, to_uri: str) -> str:
         content = Template(redirect_template).substitute({"to_uri": to_uri})
 
         return content
+
+
+def collect_redirects_for_linkcheck(app):
+    if not isinstance(app.builder, CheckExternalLinksBuilder):
+        return
+
+    rr = Reredirects(app)
+    redirects = rr.grab_redirects()
+
+    for docname, target in redirects.items():
+        if new_target := app.emit_firstresult("linkcheck-process-uri", target):
+            target = new_target
+        if urlparse(target).scheme not in ("http", "https"):
+            # Checking redirects to other pages of the same documentation is not
+            # supported for now.
+            continue
+        docpath = app.env.doc2path(docname)
+        hyperlink = Hyperlink(uri=target, docname=docname, docpath=docpath, lineno=-1)
+        app.builder.hyperlinks[target] = hyperlink

test-requirements.txt

@@ -1 +1 @@
-sphinx==5.3.0
+sphinx==7.2.6