[2014] Forbid expose of a ViewUsage in this same ViewUsage

CHANGELOG.adoc

@@ -39,6 +39,7 @@ The property `SysONTestsProperties#ELASTICSEARCH` has been removed, tests that r
 For example `ViewUsage` elements are no longer rendered in _parts_ compartments.
 - https://github.com/eclipse-syson/syson/issues/1981[#1981] [export] Fix an error during textual export where `Expose` elements with apostrophes in their name were not properly escaped.
 - https://github.com/eclipse-syson/syson/issues/1983[#1983] [metamodel] `reqId` and `declaredShortName` properties of `RequirementDefinition` and `RequirementUsage` are now synchronized, as required by the SysMLv2 specification.
+- https://github.com/eclipse-syson/syson/issues/2014[#2014] [diagrams] Forbid the expose of a `ViewUsage` in this same `ViewUsage`, directly or indirectly (i.e. through others exposed `ViewUsages`).
 
 === Improvements
 

backend/application/syson-application/src/test/java/org/eclipse/syson/application/controllers/diagrams/general/view/GVViewUsageCircularExposeTests.java

@@ -0,0 +1,186 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.controllers.diagrams.general.view;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.eclipse.sirius.components.diagrams.tests.DiagramEventPayloadConsumer.assertRefreshedDiagramThat;
+
+import java.time.Duration;
+import java.util.Optional;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+
+import org.eclipse.sirius.components.collaborative.diagrams.dto.DiagramEventInput;
+import org.eclipse.sirius.components.collaborative.diagrams.dto.DiagramRefreshedEventPayload;
+import org.eclipse.sirius.components.core.api.IObjectSearchService;
+import org.eclipse.sirius.components.diagrams.Diagram;
+import org.eclipse.sirius.components.diagrams.tests.navigation.DiagramNavigator;
+import org.eclipse.sirius.components.graphql.tests.ExecuteEditingContextFunctionInput;
+import org.eclipse.sirius.components.graphql.tests.ExecuteEditingContextFunctionSuccessPayload;
+import org.eclipse.sirius.components.graphql.tests.api.IExecuteEditingContextFunctionRunner;
+import org.eclipse.sirius.web.tests.services.api.IGivenInitialServerState;
+import org.eclipse.syson.AbstractIntegrationTests;
+import org.eclipse.syson.GivenSysONServer;
+import org.eclipse.syson.application.controllers.diagrams.testers.DropFromExplorerTester;
+import org.eclipse.syson.application.data.GVViewUsageCircularExposeTestProjectData;
+import org.eclipse.syson.services.diagrams.api.IGivenDiagramSubscription;
+import org.eclipse.syson.sysml.ViewUsage;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.transaction.annotation.Transactional;
+
+import reactor.core.publisher.Flux;
+import reactor.test.StepVerifier;
+
+/**
+ * Tests the expose of ViewUsage inside in the General View diagram.
+ *
+ * @author arichard
+ */
+@Transactional
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class GVViewUsageCircularExposeTests extends AbstractIntegrationTests {
+
+    @Autowired
+    private IGivenInitialServerState givenInitialServerState;
+
+    @Autowired
+    private IGivenDiagramSubscription givenDiagramSubscription;
+
+    @Autowired
+    private DropFromExplorerTester dropFromExplorerTester;
+
+    @Autowired
+    private IExecuteEditingContextFunctionRunner executeEditingContextFunctionRunner;
+
+    @Autowired
+    private IObjectSearchService objectSearchService;
+
+    private Flux<DiagramRefreshedEventPayload> givenSubscriptionToDiagram() {
+        var diagramEventInput = new DiagramEventInput(UUID.randomUUID(),
+                GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID,
+                GVViewUsageCircularExposeTestProjectData.GraphicalIds.DIAGRAM_ID);
+        var flux = this.givenDiagramSubscription.subscribe(diagramEventInput);
+        return flux;
+    }
+
+    @BeforeEach
+    public void beforeEach() {
+        this.givenInitialServerState.initialize();
+    }
+
+    @DisplayName("GIVEN a diagram with ViewUsage nodes, WHEN the ViewUsage corresponding to the diagram is d&d into the diagram, THEN it is not exposed.")
+    @GivenSysONServer({ GVViewUsageCircularExposeTestProjectData.SCRIPT_PATH })
+    @Test
+    public void testDropViewUsageOnDiagram() {
+        var flux = this.givenSubscriptionToDiagram();
+
+        var diagram = new AtomicReference<Diagram>();
+
+        Consumer<Object> initialDiagramContentConsumer = assertRefreshedDiagramThat(diag -> {
+            diagram.set(diag);
+            assertThat(new DiagramNavigator(diag).findDiagramNodeCount()).isEqualTo(2);
+        });
+
+        Runnable dropFromExplorerRunnable = () -> {
+            this.dropFromExplorerTester.dropFromExplorerOnDiagram(GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID, diagram,
+                    GVViewUsageCircularExposeTestProjectData.SemanticIds.VIEW_USAGE_VIEW1_ID);
+        };
+
+        Consumer<Object> updatedDiagramContentConsumer = assertRefreshedDiagramThat(diag -> {
+            assertThat(new DiagramNavigator(diag).findDiagramNodeCount()).isEqualTo(2);
+        });
+
+        Runnable checkSemanticData = () -> {
+            var input = new ExecuteEditingContextFunctionInput(UUID.randomUUID(), GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID,
+                    (editingContext, executeEditingContextFunctionInput) -> {
+                        Optional<Object> optViewUsage1 = this.objectSearchService.getObject(editingContext, GVViewUsageCircularExposeTestProjectData.SemanticIds.VIEW_USAGE_VIEW1_ID);
+                        assertThat(optViewUsage1).isPresent().get().isInstanceOf(ViewUsage.class);
+                        ViewUsage viewUsage1 = (ViewUsage) optViewUsage1.get();
+                        assertThat(viewUsage1.getExposedElement()).hasSize(1);
+                        assertThat(viewUsage1.getExposedElement()).doesNotContain(viewUsage1);
+                        return new ExecuteEditingContextFunctionSuccessPayload(executeEditingContextFunctionInput.id(), true);
+                    });
+            var payload = this.executeEditingContextFunctionRunner.execute(input).block();
+            assertThat(payload).isInstanceOf(ExecuteEditingContextFunctionSuccessPayload.class);
+        };
+
+        StepVerifier.create(flux)
+                .consumeNextWith(initialDiagramContentConsumer)
+                .then(dropFromExplorerRunnable)
+                .consumeNextWith(updatedDiagramContentConsumer)
+                .then(checkSemanticData)
+                .thenCancel()
+                .verify(Duration.ofSeconds(10));
+    }
+
+    @DisplayName("GIVEN a diagram with ViewUsage nodes, WHEN the ViewUsage corresponding to the diagram is d&d into a ViewUsage node, THEN it is not exposed.")
+    @GivenSysONServer({ GVViewUsageCircularExposeTestProjectData.SCRIPT_PATH })
+    @Test
+    public void testDropViewUsageOnViewUsageNode() {
+        var flux = this.givenSubscriptionToDiagram();
+
+        var diagram = new AtomicReference<Diagram>();
+
+        Consumer<Object> initialDiagramContentConsumer = assertRefreshedDiagramThat(diag -> {
+            diagram.set(diag);
+            assertThat(new DiagramNavigator(diag).findDiagramNodeCount()).isEqualTo(2);
+        });
+
+        Runnable dropFromExplorerOnTopNodeRunnable = () -> {
+            this.dropFromExplorerTester.dropFromExplorerOnDiagramElement(GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID, diagram,
+                    GVViewUsageCircularExposeTestProjectData.SemanticIds.VIEW_USAGE_VIEW1_ID, GVViewUsageCircularExposeTestProjectData.GraphicalIds.VIEW_USAGE_VIEW2_ID);
+        };
+
+        Consumer<Object> updatedDiagramContentConsumerAfterDropOnTopNode = assertRefreshedDiagramThat(diag -> {
+            assertThat(new DiagramNavigator(diag).findDiagramNodeCount()).isEqualTo(2);
+        });
+
+        Runnable dropFromExplorerOnNestedNodeRunnable = () -> {
+            this.dropFromExplorerTester.dropFromExplorerOnDiagramElement(GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID, diagram,
+                    GVViewUsageCircularExposeTestProjectData.SemanticIds.VIEW_USAGE_VIEW1_ID, GVViewUsageCircularExposeTestProjectData.GraphicalIds.VIEW_USAGE_VIEW3_ID);
+        };
+
+        Consumer<Object> updatedDiagramContentConsumerAfterDropOnNestedNode = assertRefreshedDiagramThat(diag -> {
+            assertThat(new DiagramNavigator(diag).findDiagramNodeCount()).isEqualTo(2);
+        });
+
+        Runnable checkSemanticData = () -> {
+            var input = new ExecuteEditingContextFunctionInput(UUID.randomUUID(), GVViewUsageCircularExposeTestProjectData.EDITING_CONTEXT_ID,
+                    (editingContext, executeEditingContextFunctionInput) -> {
+                        Optional<Object> optViewUsage1 = this.objectSearchService.getObject(editingContext, GVViewUsageCircularExposeTestProjectData.SemanticIds.VIEW_USAGE_VIEW1_ID);
+                        assertThat(optViewUsage1).isPresent().get().isInstanceOf(ViewUsage.class);
+                        ViewUsage viewUsage1 = (ViewUsage) optViewUsage1.get();
+                        assertThat(viewUsage1.getExposedElement()).hasSize(1);
+                        assertThat(viewUsage1.getExposedElement()).doesNotContain(viewUsage1);
+                        return new ExecuteEditingContextFunctionSuccessPayload(executeEditingContextFunctionInput.id(), true);
+                    });
+            var payload = this.executeEditingContextFunctionRunner.execute(input).block();
+            assertThat(payload).isInstanceOf(ExecuteEditingContextFunctionSuccessPayload.class);
+        };
+
+        StepVerifier.create(flux)
+                .consumeNextWith(initialDiagramContentConsumer)
+                .then(dropFromExplorerOnTopNodeRunnable)
+                .consumeNextWith(updatedDiagramContentConsumerAfterDropOnTopNode)
+                .then(dropFromExplorerOnNestedNodeRunnable)
+                .consumeNextWith(updatedDiagramContentConsumerAfterDropOnNestedNode)
+                .then(checkSemanticData)
+                .thenCancel()
+                .verify(Duration.ofSeconds(10));
+    }
+}

backend/application/syson-application/src/test/java/org/eclipse/syson/application/controllers/diagrams/testers/DropFromExplorerTester.java

@@ -45,8 +45,12 @@ public class DropFromExplorerTester {
     @Autowired
     private DropOnDiagramWithMessagesMutationRunner dropOnDiagramMutationRunner;
 
-    public void dropFromExplorerOnDiagram(String projectId, AtomicReference<Diagram> diagram, String semanticElementId) {
-        this.dropFromExplorer(projectId, diagram, null, semanticElementId);
+    public void dropFromExplorerOnDiagram(String projectId, AtomicReference<Diagram> diagram, String semanticElementIdToDnd) {
+        this.dropFromExplorer(projectId, diagram, null, semanticElementIdToDnd);
+    }
+
+    public void dropFromExplorerOnDiagramElement(String projectId, AtomicReference<Diagram> diagram, String semanticElementIdToDnd, String targetNodeId) {
+        this.dropFromExplorer(projectId, diagram, targetNodeId, semanticElementIdToDnd);
     }
 
     public GraphQLResult dropFromExplorer(String projectId, AtomicReference<Diagram> diagram, String targetNodeId, String semanticElementId) {

backend/application/syson-application/src/test/java/org/eclipse/syson/application/data/GVViewUsageCircularExposeTestProjectData.java

@@ -0,0 +1,52 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.syson.application.data;
+
+/**
+ * Identifiers for the "GV-ViewUsage-Circular-Expose" project.
+ *
+ * @author arichard
+ */
+public class GVViewUsageCircularExposeTestProjectData {
+
+    public static final String SCRIPT_PATH = "/scripts/database-content/GV-ViewUsage-Circular-Expose.sql";
+
+    public static final String EDITING_CONTEXT_ID = "089fc654-a72b-43da-8117-caeacc0f5f9b";
+
+    /**
+     * Ids of graphical elements.
+     */
+    public static class GraphicalIds {
+
+        public static final String DIAGRAM_ID = "a7abf1bd-5208-48da-b870-9afe66487964";
+
+        public static final String VIEW_USAGE_VIEW2_ID = "4ec4159e-9a38-3f40-b9d8-7c40a212a818";
+
+        public static final String VIEW_USAGE_VIEW3_ID = "2b1584ea-dde1-3596-931d-40af44dbee69";
+    }
+
+    /**
+     * Ids for the semantic elements.
+     */
+    public static final class SemanticIds {
+
+        public static final String PACKAGE_1_ID = "351775b8-5dc8-4c08-9f71-a12fdcb0d616";
+
+        public static final String VIEW_USAGE_VIEW1_ID = "20a54630-ce64-4e08-a171-20b9f945ffdc";
+
+        public static final String VIEW_USAGE_VIEW2_ID = "5e778a4e-dd84-43a0-80c5-5c14c4ea96a7";
+
+        public static final String VIEW_USAGE_VIEW3_ID = "8d885c6b-49d2-4eae-b50d-5250cf56e5e1";
+    }
+
+}