testing times vs. testable times

[Foka]

English Language Tests, Intermediate level

ESL/EFL Test #59 "Testing, Testing", question 6

These are indeed ......... times for the government as people are deciding whether to vote for them in the next election.

(a) tested
(b) tester
(c) testing
(d) testable

English Language Tests, Intermediate level

ESL/EFL Test #59 "Testing, Testing", answer 6

These are indeed testing times for the government as people are deciding whether to vote for them in the next election.

Correct answer: (c) testing
_________________________

Why not testable?

Foka

[Conchita]

If something is testable, it can be tested. Times are not normally tested, but they can be testing, which means 'difficult'.