diff --git a/src/test/data/DetectPolylineOverlay/DetectPolylineOverlay.ili b/src/test/data/DetectPolylineOverlay/DetectPolylineOverlay.ili
new file mode 100644
index 0000000..1ff1fa5
--- /dev/null
+++ b/src/test/data/DetectPolylineOverlay/DetectPolylineOverlay.ili
@@ -0,0 +1,21 @@
+INTERLIS 2.4;
+
+MODEL TestSuite
+  AT "mailto:info@geowerkstatt.ch" VERSION "2023-12-14" =
+
+  DOMAIN
+       !!@CRS=EPSG:2056
+       CHKoord = COORD 2460000.000 .. 2870000.000 [INTERLIS.m],
+                      1045000.000 .. 1310000.000 [INTERLIS.m],
+                      ROTATION 2 -> 1;
+
+  TOPIC FunctionTestTopic =
+
+    CLASS TestClass =
+        geometry : POLYLINE WITH (STRAIGHTS) VERTEX CHKoord WITHOUT OVERLAPS > 0.001;
+        type : (t1,t2,t3);
+    END TestClass;
+
+  END FunctionTestTopic;
+
+END TestSuite.
diff --git a/src/test/data/DetectPolylineOverlay/testdata.xtf b/src/test/data/DetectPolylineOverlay/testdata.xtf
new file mode 100644
index 0000000..3cedf90
--- /dev/null
+++ b/src/test/data/DetectPolylineOverlay/testdata.xtf
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?><ili:transfer xmlns:ili="http://www.interlis.ch/xtf/2.4/INTERLIS" xmlns:geom="http://www.interlis.ch/geometry/1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:TestSuite="http://www.interlis.ch/xtf/2.4/TestSuite">
+<ili:headersection><ili:models><ili:model>TestSuite</ili:model></ili:models><ili:sender>ili2gpkg-5.0.0-20f2bb62307ba6329a125fc6f10965ad9a4e6300</ili:sender></ili:headersection>
+<ili:datasection>
+<TestSuite:FunctionTestTopic ili:bid="TestSuite.FunctionTestTopic">
+<TestSuite:TestClass ili:tid="6a6902d8-61c0-4778-8733-ef81432e2665"><TestSuite:geometry><geom:polyline><geom:coord><geom:c1>2645657.466</geom:c1><geom:c2>1249752.542</geom:c2></geom:coord><geom:coord><geom:c1>2645626.782</geom:c1><geom:c2>1249819.826</geom:c2></geom:coord><geom:coord><geom:c1>2645687.041</geom:c1><geom:c2>1249842.746</geom:c2></geom:coord><geom:coord><geom:c1>2645691.702</geom:c1><geom:c2>1249830.036</geom:c2></geom:coord><geom:coord><geom:c1>2645693.141</geom:c1><geom:c2>1249826.110</geom:c2></geom:coord></geom:polyline></TestSuite:geometry><TestSuite:type>t1</TestSuite:type></TestSuite:TestClass>
+<TestSuite:TestClass ili:tid="dc1c980a-598d-4c1e-8a9f-ab2f81b6a433"><TestSuite:geometry><geom:polyline><geom:coord><geom:c1>2645542.677</geom:c1><geom:c2>1249774.538</geom:c2></geom:coord><geom:coord><geom:c1>2645543.027</geom:c1><geom:c2>1249774.761</geom:c2></geom:coord><geom:coord><geom:c1>2645564.119</geom:c1><geom:c2>1249788.217</geom:c2></geom:coord><geom:coord><geom:c1>2645584.822</geom:c1><geom:c2>1249800.602</geom:c2></geom:coord><geom:coord><geom:c1>2645613.103</geom:c1><geom:c2>1249812.986</geom:c2></geom:coord><geom:coord><geom:c1>2645625.673</geom:c1><geom:c2>1249785.629</geom:c2></geom:coord><geom:coord><geom:c1>2645629.624</geom:c1><geom:c2>1249777.049</geom:c2></geom:coord><geom:coord><geom:c1>2645637.503</geom:c1><geom:c2>1249759.936</geom:c2></geom:coord></geom:polyline></TestSuite:geometry><TestSuite:type>t1</TestSuite:type></TestSuite:TestClass>
+<TestSuite:TestClass ili:tid="be5879c9-9406-4d2f-9205-dbd4b85fc385"><TestSuite:geometry><geom:polyline><geom:coord><geom:c1>2645691.702</geom:c1><geom:c2>1249830.036</geom:c2></geom:coord><geom:coord><geom:c1>2645693.141</geom:c1><geom:c2>1249826.110</geom:c2></geom:coord><geom:coord><geom:c1>2645699.241</geom:c1><geom:c2>1249810.722</geom:c2></geom:coord><geom:coord><geom:c1>2645704.139</geom:c1><geom:c2>1249797.921</geom:c2></geom:coord></geom:polyline></TestSuite:geometry><TestSuite:type>t1</TestSuite:type></TestSuite:TestClass>
+<TestSuite:TestClass ili:tid="1bf1e7c0-4f03-4823-a04b-106a6948cb7c"><TestSuite:geometry><geom:polyline><geom:coord><geom:c1>2645543.027</geom:c1><geom:c2>1249774.761</geom:c2></geom:coord><geom:coord><geom:c1>2645564.119</geom:c1><geom:c2>1249788.217</geom:c2></geom:coord><geom:coord><geom:c1>2645565.875</geom:c1><geom:c2>1249785.306</geom:c2></geom:coord><geom:coord><geom:c1>2645572.530</geom:c1><geom:c2>1249789.557</geom:c2></geom:coord><geom:coord><geom:c1>2645581.032</geom:c1><geom:c2>1249773.106</geom:c2></geom:coord></geom:polyline></TestSuite:geometry><TestSuite:type>t2</TestSuite:type></TestSuite:TestClass>
+<TestSuite:TestClass ili:tid="15ff699c-b6a9-498e-a394-58af6ae0a8ef"><TestSuite:geometry><geom:polyline><geom:coord><geom:c1>2645549.805</geom:c1><geom:c2>1249782.568</geom:c2></geom:coord><geom:coord><geom:c1>2645564.778</geom:c1><geom:c2>1249757.798</geom:c2></geom:coord></geom:polyline></TestSuite:geometry><TestSuite:type>t3</TestSuite:type></TestSuite:TestClass>
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+</TestSuite:FunctionTestTopic>
+</ili:datasection>
+</ili:transfer>
\ No newline at end of file