FIX: handle missing __version__ in check_version (#13870)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: baris-talar

doc/changes/dev/13870.bugfix.rst

@@ -0,0 +1 @@
+Fix handling of optional dependencies that don't specify a version attribute, by :newcontrib:`Baris Talar`.

doc/changes/names.inc

@@ -36,6 +36,7 @@
 .. _Asish Panda: https://github.com/kaichogami
 .. _Austin Hurst: https://github.com/a-hurst
 .. _Ayushi Satodiya: https://github.com/ayuclan
+.. _Baris Talar: https://github.com/baris-talar
 .. _Beige Jin: https://github.com/BeiGeJin
 .. _Ben Beasley: https://github.com/musicinmybrain
 .. _Benedikt Ehinger: https://www.benediktehinger.de

mne/utils/check.py

@@ -83,7 +83,9 @@ def check_version(library, min_version="0.0", *, strip=True, return_version=Fals
     Parameters
     ----------
     library : str
-        The library name to import. Must have a ``__version__`` property.
+        The library name to import. Should have a ``__version__`` property;
+        if absent and ``min_version`` is specified, the version check will
+        fail.
     min_version : str
         The minimum version string. Anything that matches
         ``'(\d+ | [a-z]+ | \.)'``. Can also be empty to skip version
@@ -120,11 +122,14 @@ def check_version(library, min_version="0.0", *, strip=True, return_version=Fals
         check_version = min_version and min_version != "0.0"
         get_version = check_version or return_version
         if get_version:
-            version = library.__version__
-            if strip:
+            try:
+                version = library.__version__
+            except AttributeError:
+                version = None
+            if version is not None and strip:
                 version = _strip_dev(version)
         if check_version:
-            if _compare_version(version, "<", min_version):
+            if version is None or _compare_version(version, "<", min_version):
                 ok = False
     out = (ok, version) if return_version else ok
     return out

mne/utils/tests/test_check.py

@@ -415,3 +415,19 @@ def test_soft_import():
     """Test _soft_import."""
     with pytest.raises(RuntimeError, match=r".* the module mne>=999 \(found version.*"):
         _soft_import("mne", "testing", min_version="999")
+
+
+def test_soft_import_missing_version(monkeypatch):
+    """Test _soft_import handles packages without __version__."""
+    import types
+
+    fake_mod = types.ModuleType("fake_no_version")
+    monkeypatch.setitem(sys.modules, "fake_no_version", fake_mod)
+
+    # No min_version: should succeed even without __version__
+    mod = _soft_import("fake_no_version", "testing", strict=True)
+    assert mod is fake_mod
+
+    # With min_version: should fail because __version__ is absent
+    with pytest.raises(RuntimeError, match="module fake_no_version"):
+        _soft_import("fake_no_version", "testing", strict=True, min_version="1.0")