Add subscribe to listenerApi

Author: markerikson

packages/action-listener-middleware/src/index.ts

@@ -110,6 +110,7 @@ export interface ActionListenerMiddlewareAPI<S, D extends Dispatch<AnyAction>>
   extends MiddlewareAPI<D, S> {
   getOriginalState: () => S
   unsubscribe(): void
+  subscribe(): void
   condition: ConditionFunction<S>
   currentPhase: MiddlewarePhase
   // TODO Figure out how to pass this through the other types correctly
@@ -479,6 +480,9 @@ export function createActionListenerMiddleware<
             currentPhase,
             extra,
             unsubscribe: entry.unsubscribe,
+            subscribe: () => {
+              listenerMap.set(entry.id, entry)
+            },
           })
         } catch (listenerError) {
           safelyNotifyError(onError, listenerError)

packages/action-listener-middleware/src/tests/listenerMiddleware.test.ts

@@ -27,6 +27,7 @@ const middlewareApi = {
   dispatch: expect.any(Function),
   currentPhase: expect.stringMatching(/beforeReducer|afterReducer/),
   unsubscribe: expect.any(Function),
+  subscribe: expect.any(Function),
 }
 
 const noop = () => {}
@@ -419,6 +420,36 @@ describe('createActionListenerMiddleware', () => {
     ])
   })
 
+  test('Can re-subscribe via middleware api', async () => {
+    let numListenerRuns = 0
+    middleware.addListener({
+      actionCreator: testAction1,
+      listener: async (action, listenerApi) => {
+        numListenerRuns++
+
+        listenerApi.unsubscribe()
+
+        await listenerApi.condition(testAction2.match)
+
+        listenerApi.subscribe()
+      },
+    })
+
+    store.dispatch(testAction1('a'))
+    expect(numListenerRuns).toBe(1)
+
+    store.dispatch(testAction1('a'))
+    expect(numListenerRuns).toBe(1)
+
+    store.dispatch(testAction2('b'))
+    expect(numListenerRuns).toBe(1)
+
+    await delay(5)
+
+    store.dispatch(testAction1('b'))
+    expect(numListenerRuns).toBe(2)
+  })
+
   const whenMap: [When, string, string, number][] = [
     [undefined, 'reducer', 'listener', 1],
     ['beforeReducer', 'listener', 'reducer', 1],