fix saga when no choice matched throw NPE bug

common/src/main/java/io/seata/common/exception/FrameworkErrorCode.java

@@ -206,6 +206,11 @@ public enum FrameworkErrorCode {
      */
     StateMachineExecutionTimeout("0421", "State machine execution timeout", "State machine execution timeout"),
 
+    /**
+     * State machine execution no choice matched
+     */
+    StateMachineNoChoiceMatched("0422", "State machine no choice matched", "State machine no choice matched"),
+
     /**
      * Undefined error
      */

saga/seata-saga-engine/src/main/java/io/seata/saga/engine/pcext/handlers/ChoiceStateHandler.java

@@ -19,17 +19,22 @@
 import java.util.List;
 import java.util.Map;
 
+import io.seata.common.exception.FrameworkErrorCode;
 import io.seata.saga.engine.StateMachineConfig;
 import io.seata.saga.engine.evaluation.Evaluator;
 import io.seata.saga.engine.evaluation.EvaluatorFactory;
 import io.seata.saga.engine.evaluation.EvaluatorFactoryManager;
 import io.seata.saga.engine.exception.EngineExecutionException;
 import io.seata.saga.engine.pcext.StateHandler;
 import io.seata.saga.engine.pcext.StateInstruction;
+import io.seata.saga.engine.pcext.utils.EngineUtils;
+import io.seata.saga.engine.utils.ExceptionUtils;
 import io.seata.saga.proctrl.ProcessContext;
 import io.seata.saga.statelang.domain.ChoiceState;
 import io.seata.saga.statelang.domain.DomainConstants;
+import io.seata.saga.statelang.domain.StateMachineInstance;
 import io.seata.saga.statelang.domain.impl.ChoiceStateImpl;
+import org.springframework.util.StringUtils;
 
 /**
  * ChoiceState Handler
@@ -74,6 +79,18 @@ public void process(ProcessContext context) throws EngineExecutionException {
             }
         }
 
+        if (StringUtils.isEmpty(choiceState.getDefault())) {
+
+            StateMachineInstance stateMachineInstance = (StateMachineInstance)context.getVariable(
+                    DomainConstants.VAR_NAME_STATEMACHINE_INST);
+
+            EngineExecutionException exception = ExceptionUtils.createEngineExecutionException(FrameworkErrorCode.StateMachineNoChoiceMatched, "No choice matched, maybe it is a bug. Choice state name: " + choiceState.getName(), stateMachineInstance, null);
+
+            EngineUtils.failStateMachine(context, exception);
+
+            throw exception;
+        }
+
         context.setVariable(DomainConstants.VAR_NAME_CURRENT_CHOICE, choiceState.getDefault());
     }
 

test/src/test/java/io/seata/saga/engine/db/StateMachineDBTests.java

@@ -107,6 +107,26 @@ public void testSimpleStateMachineWithChoice() {
         System.out.println("====== cost :" + cost);
     }
 
+    @Test
+    public void testSimpleStateMachineWithChoiceNoDefault() {
+
+        long start = System.currentTimeMillis();
+
+        Map<String, Object> paramMap = new HashMap<>();
+        paramMap.put("a", 3);
+
+        String stateMachineName = "simpleChoiceNoDefaultTestStateMachine";
+
+        try {
+            stateMachineEngine.start(stateMachineName, null, paramMap);
+        } catch (EngineExecutionException e) {
+            e.printStackTrace(System.out);
+            Assertions.assertNotNull(e);
+        }
+        long cost = System.currentTimeMillis() - start;
+        System.out.println("====== cost :" + cost);
+    }
+
     @Test
     public void testSimpleStateMachineWithChoiceAndEnd() {
 

test/src/test/resources/saga/statelang/simple_statelang_with_choice_no_default.json

@@ -0,0 +1,38 @@
+{
+    "Name": "simpleChoiceNoDefaultTestStateMachine",
+    "Comment": "带条件分支但没有默认分支的测试状态机定义",
+    "StartState": "FirstState",
+    "Version": "0.0.1",
+    "States": {
+        "FirstState": {
+            "Type": "ServiceTask",
+            "ServiceName": "demoService",
+            "ServiceMethod": "foo",
+            "IsForUpdate": true,
+            "Next": "ChoiceState"
+        },
+        "ChoiceState":{
+            "Type": "Choice",
+            "Choices":[
+                {
+                    "Expression":"[a] == 1",
+                    "Next":"SecondState"
+                },
+                {
+                    "Expression":"[a] == 2",
+                    "Next":"ThirdState"
+                }
+            ]
+        },
+        "SecondState": {
+            "Type": "ServiceTask",
+            "ServiceName": "demoService",
+            "ServiceMethod": "bar"
+        },
+        "ThirdState": {
+            "Type": "ServiceTask",
+            "ServiceName": "demoService",
+            "ServiceMethod": "foo"
+        }
+    }
+}