Load test data as fixtures

[jessicayuen]

Move large test files into their own separate files and load as fixtures, so that it is easier to see what tests are being run.

Also, it might be good to take advantage of go subtests as well. This will allow for more descriptive failures instead of the whole testing failing. e.g:

cases := []struct{
name string
}{}

for _, case := range cases {
t.Run(string, func(t *testing.T) {
// where the magic happens
})
}