Porting tests from initialize_cameras_landmarks_basic to test initialize_cameras_landmarks

[OwenMcGee]

Currently doesn't compile due to issues in the evaluate_initializer() helper function. With the lines calling that function commented out, all tests currently run and succeed aside from subset_init, which I haven't yet altered.

The helper function helper() (to be renamed) condenses repeat code from the original initialize_cameras_landmarks_basic tests. I also adjusted the configure_algo() helper function to set additional config values that weren't needed in the original basic tests.

[OwenMcGee]

Tests currently fail in the evaluate_initialization helper function, as the est_cams variable is a nullptr. The variable should be set in the initialize function in initialize_cameras_landmarks.cxx, but isn't due to functions returning too early (these checks should probably throw exceptions, rather than just returning early)

[OwenMcGee]

This is necessary because the initialize() function sets its fourth parameter constraints to have a default value of nullptr, which as far as I can tell will always result in a segmentation fault in this function . This addition (checking for nullptr) stops the segmentation fault, but I believe might cause issues later on with variables not being defined when they should be.

Unless I'm mistaken, nowhere currently calls the initialize() function using the default value for constraints (doing so would cause a seg fault, I believe), so it would seem the better option here would be to simply change the function to not have a default value for that parameter. This would also necessitate passing in real values for it in the test file

[OwenMcGee]

Documented this issue in #1639

[mleotta]

Yes, this is the right thing to do. Though you could more compactly write if (constraints && since the value of a nullptr is zero which casts to false in Boolean.

[sedrakSofthenge]

Better to move this check right after cam->clear(); call before "for" loop, since if constraints is nullptr, the loop is useless. Something like this
cams->clear(); if (!constraints) { return false; }
it can be returned immediately because anway after it goes out of if-else block, cams->size() < 2 condition is being checked, which means it will always return false there, so we can leave the function immediately. Otherwise for loop needs to be in block if (constraints) { for ...