fix: install hilla-generator dependencies if Hilla is available (#23012) (#23029)

Adds hilla-generator-* dependencies to package.json when Hilla is available via EndpointRequestUtil.isHillaAvailable(), not only when Hilla is used (FrontendUtils.isHillaUsed(...)).

Fixes: vaadin/hilla#4283

Co-authored-by: Tomi Virtanen <tltv@vaadin.com>

Author: vaadin-bot

flow-server/src/main/java/com/vaadin/flow/server/frontend/NodeUpdater.java

@@ -41,6 +41,7 @@
 import com.vaadin.flow.internal.JacksonUtils;
 import com.vaadin.flow.internal.JsonDecodingException;
 import com.vaadin.flow.internal.StringUtil;
+import com.vaadin.flow.internal.hilla.EndpointRequestUtil;
 import com.vaadin.flow.server.Constants;
 import com.vaadin.flow.server.frontend.scanner.ClassFinder;
 import com.vaadin.flow.server.frontend.scanner.FrontendDependencies;
@@ -362,6 +363,14 @@ boolean hasPackageJson(String id) {
                 + "dependencies/" + id + "/package.json") != null;
     }
 
+    Map<String, String> readDependenciesIfAvailable(String id,
+            String packageJsonKey, String contains) {
+        return readDependenciesIfAvailable(id, packageJsonKey).entrySet()
+                .stream().filter(entry -> entry.getKey().contains(contains))
+                .collect(Collectors.toMap(Map.Entry::getKey,
+                        Map.Entry::getValue));
+    }
+
     Map<String, String> readDependenciesIfAvailable(String id,
             String packageJsonKey) {
         if (hasPackageJson(id)) {
@@ -643,6 +652,20 @@ private void putHillaComponentsDependencies(
                 dependencies.putAll(readDependenciesIfAvailable(
                         "hilla/components/lit", packageJsonKey));
             }
+        } else if (EndpointRequestUtil.isHillaAvailable()) {
+            // Add dependencies for hilla-generator in case Hilla is available
+            // in the classpath. This ensures that 'generate' Maven/Gradle goal
+            // has required dependencies installed even when Hilla views are not
+            // used.
+            if (options.isReactEnabled()) {
+                dependencies.putAll(
+                        readDependenciesIfAvailable("hilla/components/react",
+                                packageJsonKey, "@vaadin/hilla-generator-"));
+            } else {
+                dependencies.putAll(
+                        readDependenciesIfAvailable("hilla/components/lit",
+                                packageJsonKey, "@vaadin/hilla-generator-"));
+            }
         }
     }
 

flow-server/src/test/java/com/vaadin/flow/server/frontend/NodeUpdaterTest.java

@@ -41,6 +41,7 @@
 
 import com.vaadin.experimental.FeatureFlags;
 import com.vaadin.flow.internal.JacksonUtils;
+import com.vaadin.flow.internal.hilla.EndpointRequestUtil;
 import com.vaadin.flow.server.Constants;
 import com.vaadin.flow.server.frontend.scanner.ClassFinder;
 import com.vaadin.flow.server.frontend.scanner.FrontendDependencies;
@@ -832,6 +833,56 @@ Logger log() {
         Mockito.verifyNoInteractions(log);
     }
 
+    @Test
+    public void getDefaultDependencies_hillaAvailableButNotUsed_addsGeneratorDependencies() {
+        boolean reactEnabled = options.isReactEnabled();
+        try (MockedStatic<FrontendUtils> frontendUtilsMock = Mockito
+                .mockStatic(FrontendUtils.class);
+                MockedStatic<EndpointRequestUtil> endpointUtilMock = Mockito
+                        .mockStatic(EndpointRequestUtil.class)) {
+
+            // Hilla is available in classpath but not used
+            frontendUtilsMock.when(
+                    () -> FrontendUtils.isHillaUsed(Mockito.any(File.class),
+                            Mockito.any(ClassFinder.class)))
+                    .thenReturn(false);
+            endpointUtilMock.when(EndpointRequestUtil::isHillaAvailable)
+                    .thenReturn(true);
+            frontendUtilsMock
+                    .when(() -> FrontendUtils
+                            .isReactRouterRequired(Mockito.any(File.class)))
+                    .thenReturn(true);
+
+            // Create a spy to mock the readDependenciesIfAvailable method
+            NodeUpdater spyNodeUpdater = Mockito.spy(nodeUpdater);
+            Map<String, String> mockGeneratorDeps = Map
+                    .of("@vaadin/hilla-generator-core", "2.0.0");
+            Mockito.doReturn(mockGeneratorDeps).when(spyNodeUpdater)
+                    .readDependenciesIfAvailable(Mockito.anyString(),
+                            Mockito.eq("dependencies"),
+                            Mockito.eq("@vaadin/hilla-generator-"));
+
+            // Test with React enabled
+            options.withReact(true);
+            Map<String, String> defaultDeps = spyNodeUpdater
+                    .getDefaultDependencies();
+            Assert.assertTrue(
+                    "React generator dependency should be added when Hilla is available",
+                    defaultDeps.keySet().stream().anyMatch(
+                            key -> key.contains("@vaadin/hilla-generator-")));
+
+            // Test with React disabled
+            options.withReact(false);
+            defaultDeps = spyNodeUpdater.getDefaultDependencies();
+            Assert.assertTrue(
+                    "Lit generator dependency should be added when Hilla is available",
+                    defaultDeps.keySet().stream().anyMatch(
+                            key -> key.contains("@vaadin/hilla-generator-")));
+        } finally {
+            options.withReact(reactEnabled);
+        }
+    }
+
     private String getPolymerVersion(JsonNode object) {
         JsonNode deps = object.get("dependencies");
         return deps.get("@polymer/polymer").textValue();