test37
$GPGGA,191515.001,36.150867,N,-164.749976,E,1,8,1.0,01134.1,M,30,M
Expected string length 28 but was 27. Strings differ at index 25.
  Expected: "19:15:15 36°9′3″ -164°44′60″"
  But was:  "19:15:15 36°9′3″ -164°44′0″"

Why is 60″ expected?

Actually, what is the way you convert double to int, you need to specify it in the description
Like round, cell or floor