Tests: Fix NetCDFMixin write test
There was no guarantee that the entire array of values for y would be 3.0, only the last value. We do however also add a small test that the values in the results match the values read in again from the NetCDF file.
There was no guarantee that the entire array of values for y would be 3.0, only the last value. We do however also add a small test that the values in the results match the values read in again from the NetCDF file.