Replace deprecated assertions `assert_equal(nil, ...)`
Replace deprecated assertions `assert_equal(nil, ...)`

DEPRECATED: Use assert_nil if expecting nil from test/models/observation_test.rb:880. This will fail in Minitest 6.

JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,pellaea/mushroom-observer,MushroomObserver/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,JoeCohen/mushroom-observer,pellaea/mushroom-observer,JoeCohen/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer