S3Storage is optional (#20)

* Reporting missing s3fs

* test: S3Storage test conditional if s3fs is available

OceanColor/storage.py

@@ -23,7 +23,9 @@
 
 try:
     import s3fs
+    S3FS_AVAILABLE = True
 except:
+    S3FS_AVAILABLE = False
     module_logger.debug("s3fs library is not available")
 
 
@@ -277,6 +279,10 @@ def __init__(self, root: str):
         >>> backend = S3Storage('s3://mybucket/NASA/')
         >>> 'T2004006.L3m_DAY_CHL_chlor_a_4km.nc' in backend
         """
+        if not S3FS_AVAILABLE:
+            module_logger.error("Missing s3fs library required by S3Storage")
+            raise ImportError
+
         self.root = root
         self.fs = s3fs.S3FileSystem(anon=False)
 

tests/test_storage.py

@@ -4,7 +4,13 @@
 
 import os
 import pickle
+
 import pytest
+try:
+    import s3fs
+    S3FS_AVAILABLE = True
+except:
+    S3FS_AVAILABLE = False
 
 from OceanColor.storage import parse_filename, OceanColorDB, FileSystem, S3Storage
 
@@ -104,6 +110,8 @@ def test_no_download():
     # It was not supposed to reach here
     raise
 
+
+@pytest.mark.skipif(not S3FS_AVAILABLE, reason="S3Storage is not available without s3fs")
 def test_S3Storage_path():
     backend = S3Storage("s3://mybucket/datadir")
     assert backend.path("A2019109.L3m_DAY_CHL_chlor_a_4km.nc") == 's3://mybucket/datadir/MODIS-Aqua/L3m/2019/109/A2019109.L3m_DAY_CHL_chlor_a_4km.zarr'