diff --git a/klayout/EBeam/pymacros/tests/test_waveguide_sliver.py b/klayout/EBeam/pymacros/tests/test_waveguide_sliver.py
index 2cf79095..4e2b821c 100644
--- a/klayout/EBeam/pymacros/tests/test_waveguide_sliver.py
+++ b/klayout/EBeam/pymacros/tests/test_waveguide_sliver.py
@@ -26,38 +26,44 @@
 import siepic_ebeam_pdk
 
 import os
-tech_name = 'EBeam'
-from SiEPIC.utils import get_technology, get_technology_by_name
-TECHNOLOGY = get_technology_by_name(tech_name)
 
-cell, ly = new_layout(tech_name, top_cell_name, GUI=True, overwrite = True)
+def test_sliver():
 
-waveguide_type='Strip TE 1550 nm, w=500 nm'
+    tech_name = 'EBeam'
+    from SiEPIC.utils import get_technology, get_technology_by_name
+    TECHNOLOGY = get_technology_by_name(tech_name)
 
-cell_ebeam_y = ly.create_cell('ebeam_y_1550', tech_name)
-t = pya.Trans.from_s('r0 %s, %s' % (-7400,0))
-instY1 = cell.insert(pya.CellInstArray(cell_ebeam_y.cell_index(), t))
-t = pya.Trans.from_s('r0 %s, %s' % (-7400,10e3))
-instY2 = cell.insert(pya.CellInstArray(cell_ebeam_y.cell_index(), t))
-wg1 = connect_pins_with_waveguide(instY1, 'opt2', instY2, 'opt2', waveguide_type=waveguide_type)
+    cell, ly = new_layout(tech_name, top_cell_name, GUI=True, overwrite = True)
 
-instY1.delete()
-instY2.delete()
+    waveguide_type='Strip TE 1550 nm, w=500 nm'
 
-# check for sliver:
-wg1.cell.shapes(ly.layer(ly.TECHNOLOGY['Si'])).each
-polygon = [p for p in wg1.cell.shapes(ly.layer(ly.TECHNOLOGY['Si'])).each()][0].polygon
-for p in [r for r in polygon.to_simple_polygon().each_point()]:
-    if p.x < 0:
-        print(' Polygon error: %s' %p)
+    cell_ebeam_y = ly.create_cell('ebeam_y_1550', tech_name)
+    t = pya.Trans.from_s('r0 %s, %s' % (-7400,0))
+    instY1 = cell.insert(pya.CellInstArray(cell_ebeam_y.cell_index(), t))
+    t = pya.Trans.from_s('r0 %s, %s' % (-7400,10e3))
+    instY2 = cell.insert(pya.CellInstArray(cell_ebeam_y.cell_index(), t))
+    wg1 = connect_pins_with_waveguide(instY1, 'opt2', instY2, 'opt2', waveguide_type=waveguide_type)
 
+    instY1.delete()
+    instY2.delete()
 
-# Save
-path = os.path.dirname(os.path.realpath(__file__))
-filename = 'test_waveguide_sliver'
-file_out = export_layout(cell, path, filename, relative_path = '', format='oas')
+    # check for sliver:
+    wg1.cell.shapes(ly.layer(ly.TECHNOLOGY['Si'])).each
+    polygon = [p for p in wg1.cell.shapes(ly.layer(ly.TECHNOLOGY['Si'])).each()][0].polygon
+    for p in [r for r in polygon.to_simple_polygon().each_point()]:
+        if p.x < 0:
+            print(' Polygon error: %s' %p)
 
-from SiEPIC.utils import klive
-klive.show(file_out, technology=tech_name, keep_position=True)
 
+    # Save
+    path = os.path.dirname(os.path.realpath(__file__))
+    filename = 'test_waveguide_sliver'
+    file_out = export_layout(cell, path, filename, relative_path = '', format='oas')
+
+    from SiEPIC.utils import klive
+    klive.show(file_out, technology=tech_name, keep_position=True)
+
+
+if __name__ == "__main__":
+    test_sliver()