Four case test:
Person works entirely before shift: False
Person starts work before shift and ends during shift: True
Person starts work before shift and ends after shift: True
Person starts work after shift starts and ends before shift ends: True
Person starts work after shift starts and ends after shift: True
Person works entirely after shift: False
Three case test:
Person works entirely before shift: False
Person starts work before shift and ends during shift: True
Person starts work before shift and ends after shift: True
Person starts work after shift starts and ends before shift ends: True
Person starts work after shift starts and ends after shift: True
Person works entirely after shift: False
Two case test:
Person works entirely before shift: False
Person starts work before shift and ends during shift: True
Person starts work before shift and ends after shift: True
Person starts work after shift starts and ends before shift ends: True
Person starts work after shift starts and ends after shift: True
Person works entirely after shift: False