Add test for error

tests/test_database_get.py

@@ -459,8 +459,6 @@ def stereo_db(tmpdir):
 def test_database_get(request, db, schemes, expected):
     db = request.getfixturevalue(db)
     df = db.get(schemes)
-    print(f'{expected=}')
-    print(f'{df=}')
     pd.testing.assert_frame_equal(df, expected)
 
 
@@ -669,6 +667,26 @@ def test_database_get_limit_search(
 ):
     db = request.getfixturevalue(db)
     df = db.get(schemes, tables=tables, splits=splits)
-    print(f'{expected=}')
-    print(f'{df=}')
     pd.testing.assert_frame_equal(df, expected)
+
+
+def test_database_get_errors():
+
+    # Scheme with different categorical dtypes
+    db = audformat.Database('db')
+    db.schemes['label'] = audformat.Scheme('int', labels=[0, 1])
+    db['speaker'] = audformat.MiscTable(
+        pd.Index(['s1', 's2'], dtype='string', name='speaker')
+    )
+    db['speaker']['label'] = audformat.Column()
+    db['speaker']['label'].set([1.0, 1.0])
+    db['files'] = audformat.Table(audformat.filewise_index(['f1', 'f2']))
+    db['files']['label'] = audformat.Column(scheme_id='label')
+    db['files']['label'].set([0, 1])
+    db['other'] = audformat.Table(audformat.filewise_index(['f1', 'f2']))
+    db.schemes['speaker'] = audformat.Scheme('str', labels='speaker')
+    db['other']['speaker'] = audformat.Column(scheme_id='speaker')
+    db['other']['speaker'].set(['s1', 's2'])
+    error_msg = 'All categorical data must have the same dtype.'
+    with pytest.raises(ValueError, match=error_msg):
+        db.get('label')