diff --git a/tests/test_metadata.py b/tests/test_metadata.py
index 1c9891f3..8d05b186 100644
--- a/tests/test_metadata.py
+++ b/tests/test_metadata.py
@@ -1332,7 +1332,7 @@ def tsgroup_gba():
         3: np.geomspace(1, 100, 3000),
         4: np.geomspace(1, 100, 4000),
     }
-    return nap.TsGroup(units, metadata={"label": [1, 1, 2, 2]})
+    return nap.TsGroup(units, metadata={"label": ["A", "A", "B", "B"]})
 
 
 @pytest.fixture
@@ -1349,7 +1349,7 @@ def tsdframe_gba():
         t=np.linspace(1, 100, 1000),
         d=np.random.rand(1000, 4),
         time_units="s",
-        metadata={"label": [1, 1, 2, 2]},
+        metadata={"label": ["x", "x", "y", "y"]},
     )
 
 
@@ -1357,6 +1357,7 @@ def test_metadata_groupby_apply_tuning_curves(tsgroup_gba, iset_gba):
 
     feature = nap.Tsd(t=np.linspace(1, 100, 100), d=np.tile(np.arange(5), 20))
 
+    # apply to intervalset
     out = iset_gba.groupby_apply(
         "label",
         nap.compute_1d_tuning_curves,
@@ -1371,6 +1372,19 @@ def test_metadata_groupby_apply_tuning_curves(tsgroup_gba, iset_gba):
         )
         pd.testing.assert_frame_equal(out[grp], tmp)
 
+    # apply to tsgroup
+    out2 = tsgroup_gba.groupby_apply(
+        "label",
+        nap.compute_1d_tuning_curves,
+        feature=feature,
+        nb_bins=5,
+    )
+    # make sure groups are different
+    assert out2.keys() != out.keys()
+    for grp, idx in tsgroup_gba.groupby("label").items():
+        tmp = nap.compute_1d_tuning_curves(tsgroup_gba[idx], feature, nb_bins=5)
+        pd.testing.assert_frame_equal(out2[grp], tmp)
+
 
 def test_metadata_groupby_apply_tsgroup_lambda(tsgroup_gba):
     func = lambda x: np.mean(x.rate)
@@ -1382,6 +1396,7 @@ def test_metadata_groupby_apply_tsgroup_lambda(tsgroup_gba):
 
 
 def test_metadata_groupby_apply_compute_mean_psd(tsdframe_gba, iset_gba):
+    # test on iset
     out = iset_gba.groupby_apply(
         "label",
         nap.compute_mean_power_spectral_density,
@@ -1395,6 +1410,20 @@ def test_metadata_groupby_apply_compute_mean_psd(tsdframe_gba, iset_gba):
         )
         pd.testing.assert_frame_equal(out[grp], tmp)
 
+    # test on tsdframe
+    out2 = tsdframe_gba.groupby_apply(
+        "label",
+        nap.compute_mean_power_spectral_density,
+        interval_size=1,
+    )
+    # make sure groups are different
+    assert out2.keys() != out.keys()
+    for grp, idx in tsdframe_gba.groupby("label").items():
+        tmp = nap.compute_mean_power_spectral_density(
+            tsdframe_gba[:, idx], interval_size=1
+        )
+        pd.testing.assert_frame_equal(out2[grp], tmp)
+
 
 @pytest.mark.parametrize(
     "obj",