The tests in ElectronPdfService comprises of two interfaces:
As shown in the pictures above, first the "Download as Pdf(Pic:1) " is clicked and then the "Download(Pic:2)" button is verified by the test.
But the test fails because the selector used to capture "Download as Pdf" is incorrect or does not exist, due to which the redirection to interface 2 (Pic:2) is failed and ultimately the test can't verify the "Download" button. For reference see paste: https://phabricator.wikimedia.org/P15708
The problem can be solved by replacing the selector which will be able to capture the "Download as Pdf" properly.