test abstract VolumeFile.* to increase coverage

tests/init_test.py

@@ -0,0 +1,28 @@
+import pytest
+
+import freesurfer_volume_reader
+
+
+class DummyVolumeFile(freesurfer_volume_reader.VolumeFile):
+
+    # pylint: disable=useless-super-delegation
+
+    @property
+    def absolute_path(self):
+        return super().absolute_path
+
+    def read_volumes_mm3(self):
+        return super().read_volumes_mm3()
+
+    def read_volumes_dataframe(self):
+        return super().read_volumes_dataframe()
+
+
+def test_volume_file_abstractmethod():
+    volume_file = DummyVolumeFile()
+    with pytest.raises(NotImplementedError):
+        assert volume_file.absolute_path
+    with pytest.raises(NotImplementedError):
+        volume_file.read_volumes_mm3()
+    with pytest.raises(NotImplementedError):
+        volume_file.read_volumes_dataframe()