Canonical URL: don't set it if is empty

Fix #82

Ref #83

We need to release the extension first, make sure all builds are using
that version and then release readthedocs/readthedocs.org#7540

readthedocs_ext/_templates/readthedocs-insert.html.tmpl

@@ -1,21 +1,23 @@
 
 <!-- RTD Extra Head -->
 
-{%- if pagename == "index" %}
-    {%- set canonical_page = "" %}
-{%- elif pagename.endswith("/index") %}
-    {%- set canonical_page = pagename[:-("/index"|length)] + "/" %}
-{%- else %}
-    {%- set ending = "/" if builder == "readthedocsdirhtml" else ".html" %}
-    {%- set canonical_page = pagename + ending %}
+{%- if canonical_url %}
+    {%- if pagename == "index" %}
+        {%- set canonical_page = "" %}
+    {%- elif pagename.endswith("/index") %}
+        {%- set canonical_page = pagename[:-("/index"|length)] + "/" %}
+    {%- else %}
+        {%- set ending = "/" if builder == "readthedocsdirhtml" else ".html" %}
+        {%- set canonical_page = pagename + ending %}
+    {%- endif %}
+
+    <!-- 
+    Always link to the latest version, as canonical.
+    http://docs.readthedocs.org/en/latest/canonical.html
+    -->
+    <link rel="canonical" href="{{ canonical_url|e }}{{ canonical_page }}" />
 {%- endif %}
 
-<!-- 
-Always link to the latest version, as canonical.
-http://docs.readthedocs.org/en/latest/canonical.html
--->
-<link rel="canonical" href="{{ canonical_url }}{{ canonical_page }}" />
-
 <link rel="stylesheet" href="{{ rtd_css_url }}" type="text/css" />
 
 <script type="application/json" id="READTHEDOCS_DATA">{{ rtd_data | tojson }}</script>

tests/pyexample-json/conf.py

@@ -22,3 +22,4 @@
 html_theme = 'alabaster'
 html_static_path = ['_static']
 htmlhelp_basename = 'pyexampledoc'
+html_baseurl = 'https://example.com/'

tests/pyexample/conf.py

@@ -29,4 +29,5 @@
     'user_analytics_code': '',
     'global_analytics_code': "malic''ious",
     'commit': 'deadd00d',
+    'canonical_url': 'https://example.com/"',
 }

tests/test_integration.py

@@ -1,18 +1,24 @@
 import unittest
 
-from .util import sphinx_build, build_output
+import pytest
+from sphinx import version_info
+
+from .util import build_output, sphinx_build
 
 
 class LanguageIntegrationTests(unittest.TestCase):
 
-    def _run_test(self, test_dir, test_file, test_string, builder='html'):
+    def _run_test(self, test_dir, test_file, test_string, builder='html', assert_in=True):
         with build_output(test_dir, test_file, builder) as data:
             if not isinstance(test_string, list):
                 test_strings = [test_string]
             else:
                 test_strings = test_string
             for string in test_strings:
-                self.assertIn(string, data)
+                if assert_in:
+                    self.assertIn(string, data)
+                else:
+                    self.assertNotIn(string, data)
 
 
 class IntegrationTests(LanguageIntegrationTests):
@@ -90,3 +96,28 @@ def test_escape_js_vars(self):
         with build_output('pyexample', '_build/html/index.html', builder='html') as data:
             self.assertNotIn("malic''ious", data)
             self.assertIn('malic\\u0027\\u0027ious', data)
+
+    def test_escape_canonical_url(self):
+        self._run_test(
+            'pyexample',
+            '_build/html/index.html',
+            '<link rel="canonical" href="https://example.com/&#34;" />',
+            builder='html',
+        )
+
+    @pytest.mark.skipif(version_info < (1, 8), reason='Requires sphinx>=1.8')
+    def test_canonical_url(self):
+        self._run_test(
+            'pyexample-json',
+            '_build/html/index.html',
+            'Always link to the latest version, as canonical.',
+            builder='html',
+            assert_in=False,
+        )
+
+        self._run_test(
+            'pyexample-json',
+            '_build/html/index.html',
+            '<link rel="canonical" href="https://example.com/index.html" />',
+            builder='html',
+        )