feat(index): Index module foundation (#9095)

**What**
Index module foundation

Co-authored-by: Carlos R. L. Rodrigues <37986729+carlos-r-l-rodrigues@users.noreply.github.com>

packages/modules/index/integration-tests/__fixtures__/event-bus.ts

@@ -0,0 +1,47 @@
+import {
+  EventBusTypes,
+  IEventBusModuleService,
+  Message,
+  Subscriber,
+} from "@medusajs/types"
+
+export class EventBusServiceMock implements IEventBusModuleService {
+  protected readonly subscribers_: Map<string | symbol, Set<Subscriber>> =
+    new Map()
+
+  async emit<T>(
+    messages: Message<T> | Message<T>[],
+    options?: Record<string, unknown>
+  ): Promise<void> {
+    const messages_ = Array.isArray(messages) ? messages : [messages]
+
+    for (const message of messages_) {
+      const subscribers = this.subscribers_.get(message.name)
+
+      for (const subscriber of subscribers ?? []) {
+        const { options, ...payload } = message
+        await subscriber(payload)
+      }
+    }
+  }
+
+  subscribe(event: string | symbol, subscriber: Subscriber): this {
+    this.subscribers_.set(event, new Set([subscriber]))
+    return this
+  }
+
+  unsubscribe(
+    event: string | symbol,
+    subscriber: Subscriber,
+    context?: EventBusTypes.SubscriberContext
+  ): this {
+    return this
+  }
+
+  releaseGroupedEvents(eventGroupId: string): Promise<void> {
+    throw new Error("Method not implemented.")
+  }
+  clearGroupedEvents(eventGroupId: string): Promise<void> {
+    throw new Error("Method not implemented.")
+  }
+}

packages/modules/index/integration-tests/__fixtures__/index.ts

@@ -0,0 +1,2 @@
+export * from "./event-bus"
+export * from "./schema"

packages/modules/index/integration-tests/__fixtures__/medusa-config.js

@@ -0,0 +1,38 @@
+const { defineConfig, Modules } = require("@medusajs/utils")
+const { schema } = require("./schema")
+
+export const dbName = "medusa-index-integration-2024"
+const DB_HOST = process.env.DB_HOST ?? "localhost:5432"
+const DB_USERNAME = process.env.DB_USERNAME ?? ""
+const DB_PASSWORD = process.env.DB_PASSWORD ?? ""
+const DB_URL = `postgres://${DB_USERNAME}:${DB_PASSWORD}@${DB_HOST}/${dbName}`
+
+const config = defineConfig({
+  admin: {
+    disable: true,
+  },
+  projectConfig: {
+    databaseUrl: DB_URL,
+  },
+})
+
+Object.keys(config.modules).forEach((key) => {
+  if ([Modules.EVENT_BUS].includes(key)) {
+    return
+  }
+
+  config.modules[key] = false
+})
+
+config.modules[Modules.INDEX] = {
+  resolve: "@medusajs/index",
+  dependencies: [Modules.EVENT_BUS],
+  options: {
+    schema,
+  },
+}
+
+config.modules[Modules.PRODUCT] = true
+config.modules[Modules.PRICING] = true
+
+export default config

packages/modules/index/integration-tests/__fixtures__/schema.ts

@@ -0,0 +1,28 @@
+export const schema = `
+  type Product @Listeners(values: ["product.created", "product.updated", "product.deleted"]) {
+    id: String
+    title: String
+    deep: InternalNested
+    variants: [ProductVariant]
+  }
+  
+  type InternalNested {
+    a: Int
+    obj: InternalObject
+  }
+  
+  type InternalObject {
+    b: Int
+  }
+  
+  type ProductVariant @Listeners(values: ["variant.created", "variant.updated", "variant.deleted"]) {
+    id: String
+    product_id: String
+    sku: String
+    prices: [Price]
+  }
+  
+  type Price @Listeners(values: ["price.created", "price.updated", "price.deleted"]) {
+    amount: Int
+  }
+`