Summary:
Three TODOs resolved.
1. around line 897 - we currently don't support expansion into existing variable length edges (there is a TODO in symbol_generator.cpp:213), so this should not be done at the moment.
2. around line 1025 - This TODO was on review and nobody commented, so I'm removing it. Should have done that when the diff landed.
3. around line 1560 - This does not seem possible. Edge-uniqueness checks happen within a single `[OPTIONAL ] MATCH`. If it is OPTIONAL (the case interesting here), then the uniqueness check also gets planned under the optional branch. So, if an optional fails, the uniqueness check will get skipped, as opposed to getting executed over a Null. I added an edge-case test to verify this (and checked with the planner test).
Reviewers: buda, teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D807