Improve check_xpath

Author: AA-Turner

tests/test_builders/test_build_html.py

@@ -38,11 +38,11 @@ def check_xpath(etree, fname, path, check, be_found=True):
     nodes = list(etree.findall(path))
     if check is None:
         assert nodes == [], ('found any nodes matching xpath '
-                             '%r in file %s' % (path, fname))
+                             f'{path!r} in file {fname}')
         return
     else:
         assert nodes != [], ('did not find any node matching xpath '
-                             '%r in file %s' % (path, fname))
+                             f'{path!r} in file {fname}')
     if callable(check):
         check(nodes)
     elif not check:
@@ -65,9 +65,9 @@ def get_text(node):
             if all(not rex.search(get_text(node)) for node in nodes):
                 return
 
-        raise AssertionError('%r not found in any node matching '
-                             'path %s in %s: %r' % (check, path, fname,
-                                                    [node.text for node in nodes]))
+        msg = (f'{check!r} not found in any node matching '
+               f'{path!r} in file {fname}: {[node.text for node in nodes]!r}')
+        raise AssertionError(msg)
 
 
 @pytest.mark.sphinx('html', testroot='warnings', freshenv=True)