fix(server): Validate null on UserTaskRun arrival for userId and userGroup

server/src/main/java/io/littlehorse/common/model/getable/core/usertaskrun/UserTaskRunModel.java

@@ -237,6 +237,10 @@ public void onArrival(Date time) throws NodeFailureException {
                     ? null
                     : thread.assignVariable(node.getUserGroup()).asStr().getStrVal();
 
+            if (newUserId == null && newUserGroup == null) {
+                throw new NodeFailureException(new FailureModel("Invalid user task assignment", LHConstants.VAR_ERROR));
+            }
+
             // Set owners and schedule all on-assignment hooks
             this.assignTo(newUserId, newUserGroup, true);
 

server/src/test/java/e2e/UserTaskTest.java

@@ -7,6 +7,7 @@
 import io.littlehorse.common.util.LHUtil;
 import io.littlehorse.sdk.common.LHLibUtil;
 import io.littlehorse.sdk.common.proto.CompleteUserTaskRunRequest;
+import io.littlehorse.sdk.common.proto.Failure;
 import io.littlehorse.sdk.common.proto.ListUserTaskRunRequest;
 import io.littlehorse.sdk.common.proto.LittleHorseGrpc.LittleHorseBlockingStub;
 import io.littlehorse.sdk.common.proto.NodeRun.NodeTypeCase;
@@ -40,6 +41,7 @@
 import io.littlehorse.test.internal.TestExecutionContext;
 import io.littlehorse.test.internal.step.SearchResultCaptor;
 import java.time.Duration;
+import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Function;
 import org.assertj.core.api.Assertions;
@@ -71,6 +73,9 @@ public class UserTaskTest {
     @LHWorkflow("worker-context-receives-user-details")
     private Workflow workerContextReceivesUserDetails;
 
+    @LHWorkflow("user-task-assignment")
+    private Workflow userTaskAssignment;
+
     @LHUserTaskForm(USER_TASK_DEF_NAME)
     private MyForm myForm = new MyForm();
 
@@ -323,6 +328,22 @@ void shouldScheduleAndExecuteReminderTask() {
                 .start();
     }
 
+    @Test
+    void shouldValidateUserIdOrUserGroup() {
+        workflowVerifier
+                .prepareRun(userTaskAssignment)
+                .waitForStatus(ERROR)
+                .waitForNodeRunStatus(0, 1, ERROR)
+                .thenVerifyNodeRun(0, 1, nodeRun -> {
+                    List<Failure> failures = nodeRun.getFailuresList();
+                    Assertions.assertThat(failures).hasSize(1);
+                    Failure nodeFailure = failures.get(0);
+                    Assertions.assertThat(nodeFailure.getFailureName()).isEqualTo("VAR_ERROR");
+                    Assertions.assertThat(nodeFailure.getMessage()).isEqualTo("Invalid user task assignment");
+                })
+                .start();
+    }
+
     @Test
     void verifyWorkerContextHasUserIdOrUserGroup() {
         workflowVerifier
@@ -424,6 +445,15 @@ public Workflow buildCancelUserTaskOnReassignmentWorkflow() {
         });
     }
 
+    @LHWorkflow("user-task-assignment")
+    public Workflow buildUserTaskAssignmentWorkflow() {
+        return new WorkflowImpl("user-task-assignment", wf -> {
+            WfRunVariable userId = wf.declareStr("userId");
+            WfRunVariable userGroup = wf.declareStr("userGroup");
+            wf.assignUserTask(USER_TASK_DEF_NAME, userId, userGroup);
+        });
+    }
+
     @LHTaskMethod("my-custom-task")
     public String obiwan(MyForm formData) {
         return "String was " + formData.myStr + " and int was " + formData.myInt;