test issue 289 running the layout is not idempotent

Signed-off-by: Samir Romdhani <samir.romdhani_externe@rte-france.com>

Author: samirromdhani

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/layout/PositionVoltageLevelLayout.java

@@ -62,7 +62,7 @@ public void run(LayoutParameters layoutParam) {
         calculateBusNodeCoord(getGraph(), layoutParam);
         calculateCellCoord(getGraph(), layoutParam);
 
-        getGraph().addPaddingToCoord(layoutParam);
+        getGraph().addPaddingToCoord(layoutParam);// bug
         setGraphSize(layoutParam);
 
         // Calculate all the coordinates for the middle nodes and the snake lines in the voltageLevel graph
@@ -82,7 +82,6 @@ private void setGraphSize(LayoutParameters layoutParam) {
         LayoutParameters.Padding padding = layoutParam.getVoltageLevelPadding();
         double width = widthWithoutPadding + padding.left() + padding.right();
         double height = heightWithoutPadding + padding.top() + padding.bottom();
-
         getGraph().setSize(width, height);
     }
 

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/model/graphs/VoltageLevelGraph.java

@@ -592,14 +592,14 @@ public VoltageLevelInfos getVoltageLevelInfos() {
     }
 
     public Point getCoord() {
-        return coord;
+        return coord;// new Point(0, 0);
     }
 
     public void addPaddingToCoord(LayoutParameters layoutParam) {
         LayoutParameters.Padding vlPadding = layoutParam.getVoltageLevelPadding();
         LayoutParameters.Padding dPadding = layoutParam.getDiagramPadding();
-        setCoord(coord.getX() + dPadding.left() + vlPadding.left(),
-                coord.getY() + dPadding.top() + vlPadding.top());
+        setCoord(getCoord().getX() + dPadding.left() + vlPadding.left(),
+                getCoord().getY() + dPadding.top() + vlPadding.top());
     }
 
     public void setCoord(double x, double y) {

single-line-diagram/single-line-diagram-core/src/test/java/com/powsybl/sld/LayoutIdempotencyTest.java

@@ -0,0 +1,61 @@
+/**
+ * Copyright (c) 2026, RTE (http://www.rte-france.com)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+package com.powsybl.sld;
+
+import com.powsybl.diagram.test.Networks;
+import com.powsybl.iidm.network.Country;
+import com.powsybl.iidm.network.Network;
+import com.powsybl.iidm.network.SwitchKind;
+import com.powsybl.iidm.network.TopologyKind;
+import com.powsybl.iidm.network.extensions.ConnectablePosition;
+import com.powsybl.sld.builders.NetworkGraphBuilder;
+import com.powsybl.sld.iidm.AbstractTestCaseIidm;
+import com.powsybl.sld.layout.LayoutParameters;
+import com.powsybl.sld.layout.PositionVoltageLevelLayoutFactory;
+import com.powsybl.sld.model.graphs.VoltageLevelGraph;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author Samir Romdhani {@literal <samir.romdhani at rte-france.com>}
+ */
+class LayoutIdempotencyTest extends AbstractTestCaseIidm {
+
+    LayoutParameters layoutParameter = new LayoutParameters();
+
+    @BeforeEach
+    public void setUp() {
+        network = Network.create("testCase1", "test");
+        graphBuilder = new NetworkGraphBuilder(network);
+        substation = Networks.createSubstation(network, "s", "s", Country.FR);
+        vl = Networks.createVoltageLevel(substation, "vl", "vl", TopologyKind.NODE_BREAKER, 380);
+        Networks.createBusBarSection(vl, "bbs", "bbs", 0, 1, 1);
+        Networks.createLoad(vl, "l", "l", "l", 0, ConnectablePosition.Direction.TOP, 2, 10, 10);
+        Networks.createSwitch(vl, "d", "d", SwitchKind.DISCONNECTOR, false, false, false, 0, 1);
+        Networks.createSwitch(vl, "b", "b", SwitchKind.BREAKER, false, false, false, 1, 2);
+    }
+
+    @Test
+    void layoutRunTwiceShouldProduceSameGraph() {
+        VoltageLevelGraph graph = graphBuilder.buildVoltageLevelGraph(vl.getId());
+        var layout = new PositionVoltageLevelLayoutFactory().create(graph);
+//        var layout = new SmartVoltageLevelLayoutFactory(network).create(graph);
+//        var layout = new RandomVoltageLevelLayoutFactory(40, 40).create(graph);
+        layout.run(layoutParameter);
+        String afterFirstRun = toJson(graph, "/afterFirstRun.json");
+        debugSvgFiles = true; // check .powsybl/debug-sld
+        String svgAfterFirstLayout = toSVG(graph, "/svg-after-first-layout.svg");
+        layout.run(layoutParameter);
+        String afterSecondRun = toJson(graph, "/afterSecondRun.json");
+        debugSvgFiles = true;
+        String svgAfterSecondLayout = toSVG(graph, "/svg-after-second-layout.svg");
+        assertEquals(afterFirstRun, afterSecondRun);
+        assertEquals(svgAfterFirstLayout, svgAfterSecondLayout);
+    }
+}