Keep default Search.init behavior if addons injected (#131)

* Keep default `Search.init` behavior if addons injected

The extension removes the call to `Search.init` because it needs to perform some
injection before calling this method. The old implementation of the
`readthedocs-doc-embed.js` calls this method manually after modifying some
stuff.

However, with the introduction of addons, we don't want to manipulate the
defaults and the Sphinx default search should work out-of-the-box.

To keep the default behavior when addons is enabled, we check for addons
javascript and if it's present we call `_ready(Search.init);` as the default
Sphinx code does.

See readthedocs/addons#213 for more information.

* Update test case

* Lint

* Update integration test

* Wait for the DOM to be ready before checking for the `script`

readthedocs_ext/readthedocs.py

@@ -250,7 +250,21 @@ def remove_search_init(app, exception):
     )
 
     if os.path.exists(searchtools_file):
-        replacement_text = '/* Search initialization removed for Read the Docs */'
+        replacement_text = r"""
+/* Search initialization manipulated by Read the Docs */
+/* See https://github.com/readthedocs/addons/issues/213 for more information */
+
+function triggerSearch() {
+  const addonsInjected = document.querySelector(
+          'script[src="/_/static/javascript/readthedocs-addons.js"]'
+          );
+  if (addonsInjected) {
+    Search.init();
+  }
+}
+
+_ready(triggerSearch);
+"""
         replacement_regex = re.compile(
             r'''
             ^(\$\(document\).ready\(function\s*\(\)\s*{(?:\n|\r\n?)

tests/test_integration.py

@@ -59,8 +59,12 @@ def test_included_data(self):
     def test_searchtools_is_patched(self):
         with build_output('pyexample', '_build/html/_static/searchtools.js',
                           builder='html') as data:
-            self.assertNotIn('Search.init();', data)
-            self.assertIn('Search initialization removed for Read the Docs', data)
+            search_content = "if (addonsInjected)"
+            self.assertIn(search_content, data)
+            search_content = "Search.init();"
+            self.assertIn(search_content, data)
+            search_content = "_ready(triggerSearch);"
+            self.assertIn(search_content, data)
 
     def test_generate_json_artifacts(self):
         self._run_test(