test fix

Author: profxj

prompts/linetools.md

@@ -3,3 +3,5 @@
 ## On this deprecate_linetools branch, I wish to remove all imports of linetools.  Can you confirm that I have successfully done so?
 
 ### yes, please do, but ignore the ones in the Documentation files
+
+## The test test_arc.py in tests/ is failing.  Please suggest a fix.  If you need to run it, use the "pypeit" environment in conda.

pypeit/io.py

@@ -16,6 +16,7 @@
 import gzip
 import shutil
 from packaging import version
+from typing import TYPE_CHECKING
 
 from IPython import embed
 
@@ -36,9 +37,12 @@
 
 from pypeit import msgs
 from pypeit import dataPaths
-from pypeit import onespec
 from pypeit import __version__
 
+# Avoid circular import: datamodel -> io -> onespec -> spectrographs -> detector_container -> datamodel
+if TYPE_CHECKING:
+    from pypeit import onespec
+
 # TODO -- Move this module to core/
 
 def init_record_array(shape, dtype):
@@ -981,7 +985,7 @@ def load_thar_spec():
     return fits_open(dataPaths.arclines.get_file_path('thar_spec_MM201006.fits'))
 
 
-def load_sky_spectrum(sky_file: str) -> onespec.OneSpec:
+def load_sky_spectrum(sky_file: str) -> "onespec.OneSpec":
     """
     Load a sky spectrum from the PypeIt data directory into an XSpectrum1D
     object.
@@ -997,6 +1001,8 @@ def load_sky_spectrum(sky_file: str) -> onespec.OneSpec:
     Returns:
         `onespec.OneSpec`_: Sky spectrum
     """
+    from pypeit import onespec
+
     path = dataPaths.sky_spec.get_file_path(sky_file)
 
     return onespec.OneSpec.from_xspec_file(path)