Properly add new models into the scenegraph

[nkoenig]

The edge check logic was incorrect because it was checking to see if an edge ID already existed in the sceneGraph when it should be checking if a connected between the two vertices already existed.

Without this fix, when a model is spawned it won't be added into the graph properly.

Signed-off-by: Nate Koenig [email protected]

[codecov]

Codecov Report

Merging #212 into ign-gazebo2 will increase coverage by 0.08%.
The diff coverage is 0.00%.

@@               Coverage Diff               @@
##           ign-gazebo2     #212      +/-   ##
===============================================
+ Coverage        62.25%   62.34%   +0.08%     
===============================================
  Files              123      123              
  Lines             6101     6102       +1     
===============================================
+ Hits              3798     3804       +6     
+ Misses            2303     2298       -5     

Impacted Files	Coverage Δ
src/systems/scene_broadcaster/SceneBroadcaster.cc	36.24% <0.00%> (-0.12%)	⬇️
src/SimulationRunner.cc	88.77% <0.00%> (+1.20%)	⬆️

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[chapulina]

I saw we have a test for when entities are deleted (even though the comment says otherwise):

https://github.com/ignitionrobotics/ign-gazebo/blob/e42ad43901b57a359ea16f030a88d4a7cdb32ce7/test/integration/scene_broadcaster_system.cc#L221-L222

It would be good to also test when entities are added, so we're sure this continues working.

[caguero]

Makes sense to me.

[nkoenig]

I saw we have a test for when entities are deleted (even though the comment says otherwise):

https://github.com/ignitionrobotics/ign-gazebo/blob/e42ad43901b57a359ea16f030a88d4a7cdb32ce7/test/integration/scene_broadcaster_system.cc#L221-L222

It would be good to also test when entities are added, so we're sure this continues working.

Test added: 0aa28ae