Add test for 'group_dy' without 'partition_by' (#650)

tests/unit/lib/test_datachain.py

@@ -2731,6 +2731,49 @@ def test_group_by_multiple_partition_by(test_session):
     )
 
 
+def test_group_by_no_partition_by(test_session):
+    from datachain import func
+
+    ds = (
+        DataChain.from_values(
+            col1=["a", "a", "b", "b", "b", "c"],
+            col2=[1, 2, 1, 2, 1, 2],
+            col3=[1.0, 2.0, 3.0, 4.0, 5.0, 6.0],
+            col4=["1", "2", "3", "4", "5", "6"],
+            session=test_session,
+        )
+        .order_by("col4")
+        .group_by(
+            cnt=func.count(),
+            cnt_col=func.count("col2"),
+            sum=func.sum("col3"),
+            concat=func.concat("col4"),
+            value=func.any_value("col3"),
+            collect=func.collect("col3"),
+        )
+        .save("my-ds")
+    )
+
+    assert ds.signals_schema.serialize() == {
+        "cnt": "int",
+        "cnt_col": "int",
+        "sum": "float",
+        "concat": "str",
+        "value": "float",
+        "collect": "list[float]",
+    }
+    assert ds.to_records() == [
+        {
+            "cnt": 6,
+            "cnt_col": 6,
+            "sum": 21.0,
+            "concat": "123456",
+            "value": 1.0,
+            "collect": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0],
+        },
+    ]
+
+
 def test_group_by_error(test_session):
     from datachain import func