Support zdiff

compat.md

@@ -201,7 +201,7 @@
 | [zadd]                 | :white_check_mark: | :white_check_mark: |
 | [zcard]                | :white_check_mark: | :white_check_mark: |
 | [zcount]               | :white_check_mark: | :white_check_mark: |
-| [zdiff]                | :white_check_mark: |        :x:         |
+| [zdiff]                | :white_check_mark: | :white_check_mark: |
 | [zdiffstore]           | :white_check_mark: |        :x:         |
 | [zincrby]              | :white_check_mark: | :white_check_mark: |
 | [zinter]               | :white_check_mark: |        :x:         |

src/commands/index.js

@@ -130,6 +130,7 @@ export * from './xrevrange'
 export * from './zadd'
 export * from './zcard'
 export * from './zcount'
+export * from './zdiff'
 export * from './zincrby'
 export * from './zinterstore'
 export * from './zpopmax'

src/commands/zdiff.js

@@ -0,0 +1,44 @@
+import { convertStringToBuffer } from '../commands-utils/convertStringToBuffer'
+import { zrange } from './zrange'
+import { zscore } from './zscore'
+
+export function zdiff(numkeys, ...vals) {
+  if (vals.length === 0) {
+    throw new Error("ERR wrong number of arguments for 'zdiff' command")
+  }
+
+  const [keys, withScores] =
+    vals[vals.length - 1] === 'WITHSCORES'
+      ? [vals.slice(0, -1), true]
+      : [vals, false]
+
+  if (parseInt(numkeys, 10) !== keys.length) {
+    throw new Error(
+      'ERR numkeys must match the number of keys. ' +
+        `numkeys===${numkeys} keys but got ${keys.length} keys`
+    )
+  }
+
+  const [key1Members, ...key2toNSortedSets] = keys.map(key =>
+    zrange.call(this, key, 0, -1)
+  )
+
+  const otherMembers = new Set(key2toNSortedSets.flat())
+  const members = key1Members.filter(member => !otherMembers.has(member))
+
+  if (!withScores) {
+    return members
+  }
+
+  const membersWithScores = []
+  for (const member of members) {
+    membersWithScores.push(member)
+    membersWithScores.push(zscore.call(this, keys[0], member))
+  }
+  return membersWithScores
+}
+
+export function zdiffBuffer(numkeys, ...keys) {
+  const val = zdiff.apply(this, numkeys, keys)
+  return convertStringToBuffer(val)
+}

test/integration/commands/zdiff.js

@@ -0,0 +1,118 @@
+import Redis from 'ioredis'
+
+// eslint-disable-next-line import/no-relative-parent-imports
+import { runTwinSuite } from '../../../test-utils'
+
+runTwinSuite('zdiff', command => {
+  describe(command, () => {
+    const redis = new Redis()
+
+    afterAll(() => {
+      redis.disconnect()
+    })
+
+    it('throws if not enough keys', () => {
+      redis
+        .zdiff(1, 'key1')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            "ERR wrong number of arguments for 'zdiff' command"
+          )
+        )
+    })
+
+    it('throws if not enough keys with scores', () => {
+      redis
+        .zdiff(1, 'key1', 'WITHSCORES')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            "ERR wrong number of arguments for 'zdiff' command"
+          )
+        )
+    })
+
+    it('throws if numkeys is wrong', () => {
+      redis
+        .zdiff(1, 'key1', 'key2')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            'ERR numkeys must match the number of keys'
+          )
+        )
+      redis
+        .zdiff(2, 'key1', 'key2')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            'ERR numkeys must match the number of keys'
+          )
+        )
+    })
+
+    it('throws if numkeys is wrong with scores', () => {
+      redis
+        .zdiff(1, 'key1', 'key2', 'WITHSCORES')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            'ERR numkeys must match the number of keys'
+          )
+        )
+      redis
+        .zdiff(2, 'key1', 'key2', 'WITHSCORES')
+        .catch(err =>
+          expect(err.toString()).toContain(
+            'ERR numkeys must match the number of keys'
+          )
+        )
+    })
+
+    it('should return diff between two keys', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'a', 4, 'd')
+
+      const members = await redis.zdiff(2, 'key1', 'key2')
+      expect(members).toEqual(['b', 'c'])
+    })
+
+    it('should return diff between two keys with scores', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'a', 4, 'd')
+
+      const members = await redis.zdiff(2, 'key1', 'key2', 'WITHSCORES')
+      expect(members).toEqual(['b', '2', 'c', '3'])
+    })
+
+    it('should return diff between two keys with no overlap', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'e', 4, 'f')
+
+      const members = await redis.zdiff(2, 'key1', 'key2')
+      expect(members).toEqual(['a', 'b', 'c', 'd'])
+    })
+
+    it('should return diff between two keys with no overlap with scores', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'e', 4, 'f')
+
+      const members = await redis.zdiff(2, 'key1', 'key2', 'WITHSCORES')
+      expect(members).toEqual(['a', '1', 'b', '2', 'c', '3', 'd', '4'])
+    })
+
+    it('should return diff between three keys', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'a', 4, 'd')
+      await redis.zadd('key2', 5, 'a', 6, 'c')
+
+      const members = await redis.zdiff(3, 'key1', 'key2', 'key3')
+      expect(members).toEqual(['b'])
+    })
+
+    it('should return diff between three keys with scores', async () => {
+      await redis.zadd('key1', 1, 'a', 2, 'b', 3, 'c', 4, 'd')
+      await redis.zadd('key2', 3, 'a', 4, 'd')
+      await redis.zadd('key2', 5, 'a', 6, 'c')
+
+      const members = await redis.zdiff(3, 'key1', 'key2', 'key3', 'WITHSCORES')
+      expect(members).toEqual(['b', '2'])
+    })
+  })
+})