Add unittest to downsample1d multi

holoviews/tests/core/test_operation.py

@@ -1,5 +1,8 @@
 import param
+import pytest
 
+from holoviews import NdOverlay, Overlay
+from holoviews.operation.downsample import downsample1d
 from holoviews.core.operation import Operation
 from holoviews.element import Curve
 from holoviews.element.comparison import ComparisonTestCase
@@ -68,3 +71,19 @@ def test_element_not_dynamic_with_param_method(self):
         inst = ParamClass(label='Test')
         applied = ExampleOperation(curve, dynamic=False, label=inst.dynamic_label)
         self.assertEqual(applied, curve.relabel('Test!'))
+
+
+@pytest.mark.parametrize('plottype', ['overlay', 'ndoverlay'])
+def test_downsample1d_multi(plottype):
+    N = 1000
+    assert N > downsample1d.width
+
+    if plottype == 'overlay':
+        figure = Overlay([Curve(range(N)), Curve(range(N))])
+    elif plottype == "ndoverlay":
+        figure = NdOverlay({"A": Curve(range(N)), "B": Curve(range(N))})
+
+    figure_values = downsample1d(figure, dynamic=False).data.values()
+    for n in figure_values:
+        for value in n.data.values():
+            assert value.size == downsample1d.width