perf: only call summary when the report will be used

Author: jstewmon

src/pytest_cov/plugin.py

@@ -275,7 +275,8 @@ def pytest_testnodedown(self, node, error):
             self.cov_controller.testnodedown(node, error)
 
     def _should_report(self):
-        return not (self.failed and self.options.no_cov_on_fail)
+        needed = self.options.cov_report or self.options.cov_fail_under
+        return needed and not (self.failed and self.options.no_cov_on_fail)
 
     def _failed_cov_total(self):
         cov_fail_under = self.options.cov_fail_under