Return can_read as False if no nwbfile version is found (#1934)

* add can_read catch if no nwb_version found

* add tests for can_read method

* fix comment in test description

* fix test name

* update CHANGELOG.md

* add warnings for can_read conditions

CHANGELOG.md

@@ -5,6 +5,9 @@
 ### Documentation and tutorial enhancements
 - Added pre-release pull request instructions to release process documentation @stephprince [#1928](https://github.com/NeurodataWithoutBorders/pynwb/pull/1928)
 
+### Bug fixes
+- Fixed `can_read` method to return False if no nwbfile version can be found @stephprince [#1934](https://github.com/NeurodataWithoutBorders/pynwb/pull/1934)
+
 ## PyNWB 2.8.1 (July 3, 2024)
 
 ### Documentation and tutorial enhancements

src/pynwb/__init__.py

@@ -4,6 +4,7 @@
 import os.path
 from pathlib import Path
 from copy import deepcopy
+from warnings import warn
 import h5py
 
 from hdmf.spec import NamespaceCatalog
@@ -269,7 +270,15 @@ def can_read(path: str):
             return False
         try:
             with h5py.File(path, "r") as file:   # path is HDF5 file
-                return get_nwbfile_version(file)[1][0] >= 2    # Major version of NWB >= 2
+                version_info = get_nwbfile_version(file)
+                if version_info[0] is None:
+                    warn("Cannot read because missing NWB version in the HDF5 file. The file is not a valid NWB file.")
+                    return False
+                elif version_info[1][0] < 2:    # Major versions of NWB < 2 not supported
+                    warn("Cannot read because PyNWB supports NWB files version 2 and above.")
+                    return False
+                else:
+                    return True
         except IOError:
             return False
 

tests/integration/hdf5/test_io.py

@@ -531,3 +531,41 @@ def test_round_trip_with_pathlib_path(self):
         with NWBHDF5IO(pathlib_path, 'r') as io:
             read_file = io.read()
             self.assertContainerEqual(read_file, self.nwbfile)
+
+    def test_can_read_current_nwb_file(self):
+        with NWBHDF5IO(self.path, 'w') as io:
+            io.write(self.nwbfile)
+        self.assertTrue(NWBHDF5IO.can_read(self.path))
+
+    def test_can_read_file_does_not_exits(self):
+        self.assertFalse(NWBHDF5IO.can_read('not_a_file.nwb'))
+
+    def test_can_read_file_no_version(self):
+        # write the example file
+        with NWBHDF5IO(self.path, 'w') as io:
+            io.write(self.nwbfile)
+        # remove the version attribute
+        with File(self.path, mode='a') as io:
+            del io.attrs['nwb_version']
+
+        # assert can_read returns False and warning raised
+        warn_msg = "Cannot read because missing NWB version in the HDF5 file. The file is not a valid NWB file."
+        with self.assertWarnsWith(UserWarning, warn_msg):
+            self.assertFalse(NWBHDF5IO.can_read(self.path))
+
+    def test_can_read_file_old_version(self):
+        # write the example file
+        with NWBHDF5IO(self.path, 'w') as io:
+            io.write(self.nwbfile)
+        # set the version attribute <2.0
+        with File(self.path, mode='a') as io:
+            io.attrs['nwb_version'] = "1.0.5"
+
+        # assert can_read returns False and warning raised
+        warn_msg = "Cannot read because PyNWB supports NWB files version 2 and above."
+        with self.assertWarnsWith(UserWarning, warn_msg):
+            self.assertFalse(NWBHDF5IO.can_read(self.path))
+
+    def test_can_read_file_invalid_hdf5_file(self):
+        # current file is not an HDF5 file
+        self.assertFalse(NWBHDF5IO.can_read(__file__))