fix: Period.CollidesWith

[axunonb]

• Add checks for edge cases of periods to Period.CollidesWith
  • periods with Duration.Zero do not collide
  • periods with EffectiveDuration == null (only StartTime is set) throw as they are not considered as periods (should use Contains(CalDateTime) instead
  • contiguous periods are not evaluated as colliding any more
• Remove redundant null check in Period.EffectiveEndTime
• Enhance unit test coverage for Period and FreeBusy

Resolves #811

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❌ Your project status has failed because the head coverage (67%) is below the target coverage (80%). You can increase the head coverage or adjust the target coverage.

@@         Coverage Diff         @@
##           main   #812   +/-   ##
===================================
  Coverage    67%    67%           
===================================
  Files       106    106           
  Lines      4204   4211    +7     
  Branches    945    947    +2     
===================================
+ Hits       2822   2842   +20     
+ Misses     1048   1039    -9     
+ Partials    334    330    -4     

Files with missing lines	Coverage Δ
Ical.Net/DataTypes/Period.cs	99% <100%> (+12%)	⬆️

... and 1 file with indirect coverage changes

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[minichma]

@axunonb Sorry for not being able to review any earlier. Great increase of test coverage! The only detail to consider (not sure this is the case anyways) would be that Period instances that represent an RDATE of type DATE or DATE-TIME might not have a duration set. Not sure that could be a problem in the current implementation.

[axunonb]

Not sure that could be a problem in the current implementation.

In the FreeBusyStatus context I don't see a problem. With RDATE the method is not in use internally, but right, this could cause an issue.

Great increase of test coverage

Still too low over ical.net, unfortunately, putting any code changes at risk for unintentionally breaking things.