test: check that empty vararg doesn't throw NPE

Signed-off-by: Chris Laprun <[email protected]>

Author: metacosm

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/informer/InformerEventSourceConfiguration.java

@@ -194,6 +194,9 @@ public Builder<R> withNamespaces(Set<String> namespaces) {
       return this;
     }
 
+    /**
+     * @since 5.1.1
+     */
     public Builder<R> withNamespaces(String... namespaces) {
       config.withNamespaces(Set.of(namespaces));
       return this;

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/api/config/ControllerConfigurationOverriderTest.java

@@ -89,6 +89,22 @@ private io.javaoperatorsdk.operator.api.config.ControllerConfiguration<?> create
     return configurationService.configFor(reconciler);
   }
 
+  @Test
+  void overridingNamespacesShouldNotThrowNPE() {
+    var configuration = createConfiguration(new NullReconciler());
+    configuration =
+        ControllerConfigurationOverrider.override(configuration).settingNamespaces().build();
+    assertTrue(configuration.getInformerConfig().watchAllNamespaces());
+  }
+
+  private static class NullReconciler implements Reconciler<HasMetadata> {
+    @Override
+    public UpdateControl<HasMetadata> reconcile(HasMetadata resource, Context<HasMetadata> context)
+        throws Exception {
+      return null;
+    }
+  }
+
   @Test
   void overridingNamespacesShouldWork() {
     var configuration = createConfiguration(new WatchCurrentReconciler());