feat: add basic pubsub (#1277)

src/command.js

@@ -24,6 +24,8 @@ export function throwIfInSubscriberMode(commandName, RedisMock) {
       'psubscribeBuffer',
       'unsubscribe',
       'unsubscribeBuffer',
+      'pubsub',
+      'pubsubBuffer',
       'punsubscribe',
       'punsubscribeBuffer',
       'ping',

src/commands/index.js

@@ -76,6 +76,7 @@ export * from './psetex'
 export * from './psubscribe'
 export * from './pttl'
 export * from './publish'
+export * from './pubsub'
 export * from './punsubscribe'
 export * from './quit'
 export * from './randomkey'

src/commands/pubsub.js

@@ -0,0 +1,24 @@
+import patternMatchesString from '../commands-utils/patternMatchesString'
+
+export function pubsub(subCommand, pattern) {
+  switch (subCommand) {
+    case 'CHANNELS': {
+      let channels = []
+
+      this.channels?.instanceListeners?.forEach((instanceMap, channel) => {
+        channels.push(channel)
+      })
+
+      if (pattern) {
+        channels = channels.filter(x => patternMatchesString(pattern, x))
+      }
+
+      return channels
+    }
+    default: {
+      throw new Error('Currently not implemented as a mock')
+    }
+  }
+}
+
+export const pubsubBuffer = pubsub

test/integration/commands/pubsub.js

@@ -0,0 +1,57 @@
+import Redis from 'ioredis'
+
+// eslint-disable-next-line import/no-relative-parent-imports
+import { runTwinSuite } from '../../../test-utils'
+
+const testChannels = ['emails', 'messages', 'feed']
+
+runTwinSuite('pubsub', command => {
+  // @TODO Rewrite test suite so it runs on a real Redis instance
+  ;(process.env.IS_E2E ? describe.skip : describe)(command, () => {
+    describe('CHANNELS', () => {
+      let redis
+
+      beforeEach(() => {
+        redis = new Redis({
+          host: 'pubsub',
+        })
+      })
+
+      afterEach(async () => {
+        await Promise.all(testChannels.map(x => redis.unsubscribe(x)))
+      })
+
+      test('should return 0 when publishing without subscribers', async () => {
+        expect(await redis[command]('CHANNELS')).toMatchObject([])
+      })
+
+      it('should return the single active channel', async () => {
+        redis.subscribe('emails')
+
+        expect(await redis[command]('CHANNELS')).toMatchObject(['emails'])
+      })
+
+      it('should return multiple active channels', async () => {
+        redis.subscribe('emails')
+        redis.subscribe('messages')
+        redis.subscribe('feed')
+
+        expect(await redis[command]('CHANNELS')).toMatchObject([
+          'emails',
+          'messages',
+          'feed',
+        ])
+      })
+
+      it('should return filtered channels', async () => {
+        redis.subscribe('emails')
+        redis.subscribe('messages')
+        redis.subscribe('feed')
+
+        expect(await redis[command]('CHANNELS', 'email*')).toMatchObject([
+          'emails',
+        ])
+      })
+    })
+  })
+})