feat: Add support for scheduled workflows (#7651)

We still need to:
But wanted to open the PR for early feedback on the approach

packages/modules/workflow-engine-redis/integration-tests/__fixtures__/workflow_scheduled.ts

@@ -0,0 +1,23 @@
+import { SchedulerOptions } from "@medusajs/orchestration"
+import {
+  createStep,
+  createWorkflow,
+  StepResponse,
+} from "@medusajs/workflows-sdk"
+
+export const createScheduled = (name: string, schedule?: SchedulerOptions) => {
+  const workflowScheduledStepInvoke = jest.fn((input, context) => {
+    return new StepResponse({})
+  })
+
+  const step = createStep("step_1", workflowScheduledStepInvoke)
+
+  createWorkflow(
+    { name, schedule: schedule ?? "* * * * * *" },
+    function (input) {
+      return step(input)
+    }
+  )
+
+  return workflowScheduledStepInvoke
+}

packages/modules/workflow-engine-redis/integration-tests/__tests__/index.spec.ts

@@ -10,6 +10,7 @@ import { knex } from "knex"
 import { setTimeout } from "timers/promises"
 import "../__fixtures__"
 import { DB_URL, TestDatabase } from "../utils"
+import { createScheduled } from "../__fixtures__/workflow_scheduled"
 
 const sharedPgConnection = knex<any, any>({
   client: "pg",
@@ -297,4 +298,23 @@ describe("Workflow Orchestrator module", function () {
       expect(onFinish).toHaveBeenCalledTimes(0)
     })
   })
+
+  // Note: These tests depend on actual Redis instance and waiting for the scheduled jobs to run, which isn't great.
+  // Mocking bullmq, however, would make the tests close to useless, so we can keep them very minimal and serve as smoke tests.
+  describe("Scheduled workflows", () => {
+    it("should execute a scheduled workflow", async () => {
+      const spy = createScheduled("standard")
+      await setTimeout(3100)
+      expect(spy).toHaveBeenCalledTimes(3)
+    })
+
+    it("should stop executions after the set number of executions", async () => {
+      const spy = await createScheduled("num-executions", {
+        cron: "* * * * * *",
+        numberOfExecutions: 2,
+      })
+      await setTimeout(3100)
+      expect(spy).toHaveBeenCalledTimes(2)
+    })
+  })
 })