Fixed an issue with some exit handlers being executed more than once …

…when stopping a machine (#2895)
statelyai · Dec 27, 2021 · df5ffce · df5ffce
1 parent 8435c5b
commit df5ffce
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Showing 4 changed files with 39 additions and 21 deletions.
diff --git a/.changeset/perfect-paws-explode.md b/.changeset/perfect-paws-explode.md
@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Fixed an issue with some exit handlers being executed more than once when stopping a machine.
diff --git a/packages/core/src/StateNode.ts b/packages/core/src/StateNode.ts
@@ -673,21 +673,19 @@ class StateNode<
     }
 
     const subStateKeys = keys(stateValue);
-    const subStateNodes: Array<
-      StateNode<TContext, any, TEvent, TTypestate>
-    > = subStateKeys.map((subStateKey) => this.getStateNode(subStateKey));
-
-    subStateNodes.push(this);
-
-    return subStateNodes.concat(
-      subStateKeys.reduce((allSubStateNodes, subStateKey) => {
-        const subStateNode = this.getStateNode(subStateKey).getStateNodes(
-          stateValue[subStateKey]
-        );
+    const subStateNodes: Array<StateNode<TContext, any, TEvent, TTypestate>> = [
+      this
+    ];
 
-        return allSubStateNodes.concat(subStateNode);
-      }, [] as Array<StateNode<TContext, any, TEvent, TTypestate>>)
+    subStateNodes.push(
+      ...flatten(
+        subStateKeys.map((subStateKey) =>
+          this.getStateNode(subStateKey).getStateNodes(stateValue[subStateKey])
+        )
+      )
     );
+
+    return subStateNodes;
   }
 
   /**
@@ -991,13 +989,6 @@ class StateNode<
       }
     }
 
-    if (!transition.source) {
-      transition.exitSet = [];
-
-      // Ensure that root StateNode (machine) is entered
-      transition.entrySet.push(this);
-    }
-
     const doneEvents = flatten(
       transition.entrySet.map((sn) => {
         const events: DoneEventObject[] = [];

diff --git a/packages/core/src/stateUtils.ts b/packages/core/src/stateUtils.ts
@@ -36,7 +36,7 @@ export function getAllStateNodes<TC, TE extends EventObject>(
 export function getConfiguration<TC, TE extends EventObject>(
   prevStateNodes: Iterable<StateNode<TC, any, TE, any>>,
   stateNodes: Iterable<StateNode<TC, any, TE, any>>
-): Iterable<StateNode<TC, any, TE, any>> {
+): Set<StateNode<TC, any, TE, any>> {
   const prevConfiguration = new Set(prevStateNodes);
   const prevAdjList = getAdjList(prevConfiguration);
 

diff --git a/packages/core/test/actions.test.ts b/packages/core/test/actions.test.ts
@@ -1422,6 +1422,28 @@ describe('choose', () => {
     expect(exitCalled).toBeTruthy();
     expect(childExitCalled).toBeTruthy();
   });
+
+  it('should call each exit handler only once when the service gets stopped', () => {
+    const actual: string[] = [];
+    const machine = createMachine({
+      exit: () => actual.push('root'),
+      initial: 'a',
+      states: {
+        a: {
+          exit: () => actual.push('a'),
+          initial: 'a1',
+          states: {
+            a1: {
+              exit: () => actual.push('a1')
+            }
+          }
+        }
+      }
+    });
+
+    interpret(machine).start().stop();
+    expect(actual).toEqual(['root', 'a', 'a1']);
+  });
 });
 
 describe('sendParent', () => {