Update WorkflowTest.java

operator-framework-core/src/test/java/io/javaoperatorsdk/operator/processing/dependent/workflow/WorkflowTest.java

@@ -14,6 +14,7 @@
 import io.javaoperatorsdk.operator.sample.simple.TestCustomResource;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
@@ -24,6 +25,22 @@ class WorkflowTest {
 
   ExecutorService executorService = Executors.newCachedThreadPool();
 
+  @Test
+  void zeroTopLevelDRShouldThrowException() {
+    var dr1 = mock(DependentResource.class);
+    var dr2 = mock(DependentResource.class);
+    var dr3 = mock(DependentResource.class);
+
+    var cyclicWorkflowBuilderSetup = new WorkflowBuilder<TestCustomResource>()
+        .addDependentResource(dr1).dependsOn()
+        .addDependentResource(dr2).dependsOn(dr1)
+        .addDependentResource(dr3).dependsOn(dr2)
+        .addDependentResource(dr1).dependsOn(dr2);
+
+    assertThrows(IllegalStateException.class,
+        cyclicWorkflowBuilderSetup::build);
+  }
+
   @Test
   void calculatesTopLevelResources() {
     var dr1 = mock(DependentResource.class);