Fix disconnected bus in bus breaker topology

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/svg/styles/iidm/HighlightLineStateStyleProvider.java

@@ -57,7 +57,7 @@ private boolean isBusOrBbsConnected(BusNode busNode) {
         } else {
             Bus bus = network.getBusBreakerView().getBus(equipmentId);
             if (bus != null) {
-                return bus.getConnectedTerminalStream().anyMatch(Terminal::isConnected);
+                return bus.getVoltageLevel().getBusView().getMergedBus(bus.getId()) != null;
             }
             return true; // should not happen
         }

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

@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) 2024, 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.iidm;
+
+import com.powsybl.diagram.test.Networks;
+import com.powsybl.iidm.network.*;
+import com.powsybl.sld.builders.NetworkGraphBuilder;
+import com.powsybl.sld.model.graphs.VoltageLevelGraph;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.io.IOException;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author Florian Dupuy {@literal <florian.dupuy at rte-france.com>}
+ */
+class TestCaseBusDisconnected extends AbstractTestCaseIidm {
+
+    @BeforeEach
+    @Override
+    public void setUp() throws IOException {
+        network = Network.create("testCaseBusNodeDisconnected", "testCaseBusNodeDisconnected");
+        graphBuilder = new NetworkGraphBuilder(network);
+        substation = Networks.createSubstation(network, "s", "s", Country.FR);
+
+        // bus breaker topology
+        VoltageLevel vlBb = Networks.createVoltageLevel(substation, "vlBb", "vlBb", TopologyKind.BUS_BREAKER, 225);
+        Bus b1 = vlBb.getBusBreakerView().newBus().setId("b1").add();
+        Bus b2 = vlBb.getBusBreakerView().newBus().setId("b2").add();
+        Bus b3 = vlBb.getBusBreakerView().newBus().setId("b3").add();
+        vlBb.getBusBreakerView().newSwitch().setId("s12").setBus1(b1.getId()).setBus2(b2.getId()).add();
+        vlBb.getBusBreakerView().newSwitch().setId("s23").setOpen(true).setBus1(b2.getId()).setBus2(b3.getId()).add();
+
+        // node breaker topology
+        VoltageLevel vlNb = Networks.createVoltageLevel(substation, "vlNb", "vlNb", TopologyKind.NODE_BREAKER, 225);
+        vlNb.getNodeBreakerView().newBusbarSection().setId("bbs1").setNode(0).add();
+        vlNb.getNodeBreakerView().newBusbarSection().setId("bbs2").setNode(1).add();
+        vlNb.getNodeBreakerView().newSwitch().setId("sLine").setKind(SwitchKind.DISCONNECTOR).setNode1(0).setNode2(2).add();
+        vlNb.getNodeBreakerView().newSwitch().setId("sLoad").setOpen(true).setKind(SwitchKind.DISCONNECTOR).setNode1(1).setNode2(3).add();
+        vlNb.newLoad().setNode(3).setId("load").setP0(10).setQ0(10).add();
+
+        network.newLine().setId("line")
+                .setG1(0).setB1(0).setVoltageLevel1(vlBb.getId()).setBus1(b2.getId())
+                .setG2(0).setB2(0).setVoltageLevel2(vlNb.getId()).setNode2(2)
+                .setR(1).setX(1)
+                .add();
+    }
+
+    @ParameterizedTest(name = "{0}")
+    @MethodSource("provideTestData")
+    void test(String testName, String vlId, String svgResourceName) {
+        VoltageLevelGraph g = graphBuilder.buildVoltageLevelGraph(vlId);
+        voltageLevelGraphLayout(g);
+        assertEquals(toString(svgResourceName), toSVG(g, svgResourceName));
+    }
+
+    private static List<Arguments> provideTestData() {
+        return List.of(
+                Arguments.of("Test bus connected/disconnected", "vlBb", "/TestCaseBusBreakerBusConnected.svg"),
+                Arguments.of("Test busbarSection connected/disconnected", "vlNb", "/TestCaseNodeBreakerBbsConnected.svg")
+        );
+    }
+}