fix(overmind): flush during testing

Author: christianalfoni

packages/node_modules/overmind/src/index.ts

@@ -318,7 +318,7 @@ export class Overmind<ThisConfig extends IConfiguration>
         nextTick && clearTimeout(nextTick)
         nextTick = setTimeout(flushTree, 0)
       })
-    } else if (mode.mode === MODE_DEFAULT) {
+    } else if (mode.mode === MODE_DEFAULT || mode.mode === MODE_TEST) {
       eventHub.on(EventType.OPERATOR_ASYNC, (execution) => {
         const flushData = execution.flush(true)
         if (this.devtools && flushData.mutations.length) {