feat: NIP-40 (#148)

* feat: add method for checking if event is expired

* fix: tag length check

* feat: add method for expiration check

* feat: refactor event expiration

* fix: remove stale comment

* fix: remove unused method

* fix: upsert/insert tests

* fix: failing tests

* feat: add tests for event expiration

* feat: update test

* feat: add nip 40 to supportedNips

* chore: add expires_at column to events table

* chore: use uint for expires_at

---------

Co-authored-by: Ricardo Arturo Cabral Mejía <me@ricardocabral.io>

migrations/20230203_185700_add_expires_at_to_events_table.js

@@ -0,0 +1,11 @@
+exports.up = function (knex) {
+  return knex.schema.alterTable('events', function (table) {
+    table.integer('expires_at').unsigned().nullable().index()
+  })
+}
+
+exports.down = function (knex) {
+  return knex.schema.alterTable('events', function (table) {
+    table.dropColumn('expires_at')
+  })
+}

package.json

@@ -15,7 +15,8 @@
     22,
     26,
     28,
-    33
+    33,
+    40
   ],
   "main": "src/index.ts",
   "scripts": {

src/@types/event.ts

@@ -1,5 +1,5 @@
 import { ContextMetadata, EventId, Pubkey, Tag } from './base'
-import { ContextMetadataKey, EventDeduplicationMetadataKey, EventDelegatorMetadataKey, EventKinds } from '../constants/base'
+import { ContextMetadataKey, EventDeduplicationMetadataKey, EventDelegatorMetadataKey, EventExpirationTimeMetadataKey, EventKinds } from '../constants/base'
 
 export interface BaseEvent {
   id: EventId
@@ -25,6 +25,10 @@ export interface DelegatedEvent extends Event {
   [EventDelegatorMetadataKey]?: Pubkey
 }
 
+export interface ExpiringEvent extends Event {
+  [EventExpirationTimeMetadataKey]?: number
+}
+
 export interface ParameterizedReplaceableEvent extends Event {
   [EventDeduplicationMetadataKey]: string[]
 }
@@ -42,6 +46,7 @@ export interface DBEvent {
   event_deduplication?: string | null
   first_seen: Date
   deleted_at?: Date
+  expires_at?: number
 }
 
 export interface CanonicalEvent {

src/constants/base.ts

@@ -36,6 +36,7 @@ export enum EventTags {
   //  Multicast = 'm',
   Delegation = 'delegation',
   Deduplication = 'd',
+  Expiration = 'expiration',
 }
 
 export enum PaymentsProcessors {
@@ -45,3 +46,4 @@ export enum PaymentsProcessors {
 export const EventDelegatorMetadataKey = Symbol('Delegator')
 export const EventDeduplicationMetadataKey = Symbol('Deduplication')
 export const ContextMetadataKey = Symbol('Context')
+export const EventExpirationTimeMetadataKey = Symbol('Expiration')

src/factories/event-strategy-factory.ts

@@ -10,7 +10,6 @@ import { IWebSocketAdapter } from '../@types/adapters'
 import { ParameterizedReplaceableEventStrategy } from '../handlers/event-strategies/parameterized-replaceable-event-strategy'
 import { ReplaceableEventStrategy } from '../handlers/event-strategies/replaceable-event-strategy'
 
-
 export const eventStrategyFactory = (
   eventRepository: IEventRepository,
 ): Factory<IEventStrategy<Event, Promise<void>>, [Event, IWebSocketAdapter]> =>
@@ -23,7 +22,7 @@ export const eventStrategyFactory = (
       return new DeleteEventStrategy(adapter, eventRepository)
     } else if (isParameterizedReplaceableEvent(event)) {
       return new ParameterizedReplaceableEventStrategy(adapter, eventRepository)
-    }
+    } 
 
     return new DefaultEventStrategy(adapter, eventRepository)
   }

src/handlers/event-message-handler.ts

@@ -1,10 +1,11 @@
+import { Event, ExpiringEvent  } from '../@types/event'
 import { EventRateLimit, FeeSchedule, Settings } from '../@types/settings'
-import { getEventProofOfWork, getPubkeyProofOfWork, isEventIdValid, isEventKindOrRangeMatch, isEventSignatureValid } from '../utils/event'
+import { getEventExpiration, getEventProofOfWork, getPubkeyProofOfWork, isEventIdValid, isEventKindOrRangeMatch, isEventSignatureValid, isExpiredEvent } from '../utils/event'
 import { IEventStrategy, IMessageHandler } from '../@types/message-handlers'
 import { ContextMetadataKey } from '../constants/base'
 import { createCommandResult } from '../utils/messages'
 import { createLogger } from '../factories/logger-factory'
-import { Event } from '../@types/event'
+import { EventExpirationTimeMetadataKey } from '../constants/base'
 import { Factory } from '../@types/base'
 import { IncomingEventMessage } from '../@types/messages'
 import { IRateLimiter } from '../@types/utils'
@@ -24,7 +25,7 @@ export class EventMessageHandler implements IMessageHandler {
   ) {}
 
   public async handleMessage(message: IncomingEventMessage): Promise<void> {
-    const [, event] = message
+    let [, event] = message
 
     event[ContextMetadataKey] = message[ContextMetadataKey]
 
@@ -35,6 +36,14 @@ export class EventMessageHandler implements IMessageHandler {
       return
     }
 
+    if (isExpiredEvent(event)) {
+      debug('event %s rejected: expired')
+      this.webSocket.emit(WebSocketAdapterEvent.Message, createCommandResult(event.id, false, 'event is expired'))
+      return
+    }
+
+    event = this.addExpirationMetadata(event)
+
     if (await this.isRateLimited(event)) {
       debug('event %s rejected: rate-limited')
       this.webSocket.emit(WebSocketAdapterEvent.Message, createCommandResult(event.id, false, 'rate-limited: slow down'))
@@ -261,4 +270,17 @@ export class EventMessageHandler implements IMessageHandler {
       return 'blocked: insufficient balance'
     }
   }
+
+  protected addExpirationMetadata(event: Event): Event | ExpiringEvent {
+    const eventExpiration: number = getEventExpiration(event)
+    if (eventExpiration) {
+        const expiringEvent: ExpiringEvent = {
+          ...event,
+          [EventExpirationTimeMetadataKey]: eventExpiration,
+        }
+        return expiringEvent
+    } else {
+      return event
+    }
+  }
 }

src/repositories/event-repository.ts

@@ -29,7 +29,7 @@ import {
   toPairs,
 } from 'ramda'
 
-import { ContextMetadataKey, EventDeduplicationMetadataKey, EventDelegatorMetadataKey } from '../constants/base'
+import { ContextMetadataKey, EventDeduplicationMetadataKey, EventDelegatorMetadataKey, EventExpirationTimeMetadataKey } from '../constants/base'
 import { DatabaseClient, EventId } from '../@types/base'
 import { DBEvent, Event } from '../@types/event'
 import { IEventRepository, IQueryResult } from '../@types/repositories'
@@ -182,6 +182,12 @@ export class EventRepository implements IEventRepository {
         always(null),
       ),
       remote_address: path([ContextMetadataKey as any, 'remoteAddress', 'address']),
+      expires_at: ifElse(
+        propSatisfies(is(Number), EventExpirationTimeMetadataKey),
+        pipe(prop(EventExpirationTimeMetadataKey as any), toBuffer),
+        always(null),
+      ),
+      
     })(event)
 
     return this.masterDbClient('events')
@@ -214,6 +220,11 @@ export class EventRepository implements IEventRepository {
         pipe(prop(EventDeduplicationMetadataKey as any), toJSON),
       ),
       remote_address: path([ContextMetadataKey as any, 'remoteAddress', 'address']),
+      expires_at: ifElse(
+        propSatisfies(is(Number), EventExpirationTimeMetadataKey),
+        pipe(prop(EventExpirationTimeMetadataKey as any), toBuffer),
+        always(null),
+      ),
     })(event)
 
     const query = this.masterDbClient('events')
@@ -250,6 +261,7 @@ export class EventRepository implements IEventRepository {
           event_signature: pipe(always(''), toBuffer),
           event_delegator: always(null),
           event_deduplication: pipe(always([pubkey, 5]), toJSON),
+          expires_at: always(null),
           deleted_at: always(date.toISOString()),
         })
       )

src/utils/event.ts

@@ -269,6 +269,29 @@ export const isDeleteEvent = (event: Event): boolean => {
   return event.kind === EventKinds.DELETE
 }
 
+export const isExpiredEvent = (event: Event): boolean => {
+  if (!event.tags.length) return false
+
+  const expirationTime = getEventExpiration(event)
+
+  if (!expirationTime) return false
+
+  const date = new Date()
+  const isExpired = expirationTime <= Math.floor(date.getTime() / 1000)
+
+  return isExpired
+}
+
+export const getEventExpiration = (event: Event): number | undefined => {
+  const [, rawExpirationTime] = event.tags.find((tag) => tag.length >= 2 && tag[0] === EventTags.Expiration) ?? []
+  if (!rawExpirationTime) return
+
+  const expirationTime = Number(rawExpirationTime)
+  if ((Number.isSafeInteger(expirationTime) && Math.log10(expirationTime))) {
+    return expirationTime
+  } 
+}
+
 export const getEventProofOfWork = (eventId: EventId): number => {
   return getLeadingZeroBits(Buffer.from(eventId, 'hex'))
 }

test/unit/handlers/event-message-handler.spec.ts

@@ -111,7 +111,7 @@ describe('EventMessageHandler', () => {
     })
 
     it('rejects event if invalid', async () => {
-      isEventValidStub.returns('reason')
+      isEventValidStub.resolves('reason')
 
       await handler.handleMessage(message)
 
@@ -128,6 +128,28 @@ describe('EventMessageHandler', () => {
       expect(isUserAdmitted).to.have.been.calledWithExactly(event)
       expect(strategyFactoryStub).not.to.have.been.called
     })
+    
+    it('rejects event if it is expired', async () => {
+      isEventValidStub.resolves(undefined)
+
+      const expiredEvent = {
+        ...event,
+        tags: [
+          ['expiration', '1600000'],
+        ],
+      }
+
+      const expiredEventMessage: any = [MessageType.EVENT, expiredEvent]
+
+      await handler.handleMessage(expiredEventMessage)
+
+      expect(isEventValidStub).to.have.been.calledOnceWithExactly(expiredEvent)
+
+      expect(onMessageSpy).to.have.been.calledOnceWithExactly(
+        [MessageType.OK, event.id, false, 'event is expired'],
+      )
+      expect(strategyExecuteStub).not.to.have.been.called
+    })
 
     it('does not call strategy if none given', async () => {
       isEventValidStub.returns(undefined)

test/unit/repositories/event-repository.spec.ts

@@ -435,7 +435,7 @@ describe('EventRepository', () => {
 
       const query = (repository as any).insert(event).toString()
 
-      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "remote_address") values (\'I\'\'ve set up mirroring between relays: https://i.imgur.com/HxCDipB.png\', 1648351380, NULL, X\'6b3cdd0302ded8068ad3f0269c74423ca4fee460f800f3d90103b63f14400407\', 1, X\'22e804d26ed16b68db5259e78449e96dab5d464c8f470bda3eb1a70467f2c793\', X\'b37adfed0e6398546d623536f9ddc92b95b7dc71927e1123266332659253ecd0ffa91ddf2c0a82a8426c5b363139d28534d6cac893b8a810149557a3f6d36768\', \'[["p","8355095016fddbe31fcf1453b26f613553e9758cf2263e190eac8fd96a3d3de9","wss://nostr-pub.wellorder.net"],["e","7377fa81fc6c7ae7f7f4ef8938d4a603f7bf98183b35ab128235cc92d4bebf96","wss://nostr-relay.untethr.me"]]\', \'::1\') on conflict do nothing')
+      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "expires_at", "remote_address") values (\'I\'\'ve set up mirroring between relays: https://i.imgur.com/HxCDipB.png\', 1648351380, NULL, X\'6b3cdd0302ded8068ad3f0269c74423ca4fee460f800f3d90103b63f14400407\', 1, X\'22e804d26ed16b68db5259e78449e96dab5d464c8f470bda3eb1a70467f2c793\', X\'b37adfed0e6398546d623536f9ddc92b95b7dc71927e1123266332659253ecd0ffa91ddf2c0a82a8426c5b363139d28534d6cac893b8a810149557a3f6d36768\', \'[["p","8355095016fddbe31fcf1453b26f613553e9758cf2263e190eac8fd96a3d3de9","wss://nostr-pub.wellorder.net"],["e","7377fa81fc6c7ae7f7f4ef8938d4a603f7bf98183b35ab128235cc92d4bebf96","wss://nostr-relay.untethr.me"]]\', NULL, \'::1\') on conflict do nothing')
     })
   })
 
@@ -453,7 +453,7 @@ describe('EventRepository', () => {
     it('insert stubs by pubkey & event ids', () => {
       const query = repository.insertStubs('001122', ['aabbcc', 'ddeeff']).toString()
 
-      expect(query).to.equal('insert into "events" ("deleted_at", "event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags") values (\'1970-01-20T08:57:15.425Z\', \'\', 1673835, \'["001122",5]\', NULL, X\'aabbcc\', 5, X\'001122\', X\'\', \'[]\'), (\'1970-01-20T08:57:15.425Z\', \'\', 1673835, \'["001122",5]\', NULL, X\'ddeeff\', 5, X\'001122\', X\'\', \'[]\') on conflict do nothing')
+      expect(query).to.equal('insert into "events" ("deleted_at", "event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "expires_at") values (\'1970-01-20T08:57:15.425Z\', \'\', 1673835, \'["001122",5]\', NULL, X\'aabbcc\', 5, X\'001122\', X\'\', \'[]\', NULL), (\'1970-01-20T08:57:15.425Z\', \'\', 1673835, \'["001122",5]\', NULL, X\'ddeeff\', 5, X\'001122\', X\'\', \'[]\', NULL) on conflict do nothing')
     })
   })
 
@@ -480,7 +480,7 @@ describe('EventRepository', () => {
 
       const query = repository.upsert(event).toString()
 
-      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "remote_address") values (\'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\', 1564498626, \'["55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503",0]\', NULL, X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\', 0, X\'55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503\', X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\', \'[]\', \'::1\') on conflict (event_pubkey, event_kind, event_deduplication) WHERE (event_kind = 0 OR event_kind = 3 OR event_kind = 41 OR (event_kind >= 10000 AND event_kind < 20000)) OR (event_kind >= 30000 AND event_kind < 40000) do update set "event_id" = X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\',"event_created_at" = 1564498626,"event_tags" = \'[]\',"event_content" = \'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\',"event_signature" = X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\',"event_delegator" = NULL,"remote_address" = \'::1\' where "events"."event_created_at" < 1564498626')
+      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "expires_at", "remote_address") values (\'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\', 1564498626, \'["55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503",0]\', NULL, X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\', 0, X\'55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503\', X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\', \'[]\', NULL, \'::1\') on conflict (event_pubkey, event_kind, event_deduplication) WHERE (event_kind = 0 OR event_kind = 3 OR event_kind = 41 OR (event_kind >= 10000 AND event_kind < 20000)) OR (event_kind >= 30000 AND event_kind < 40000) do update set "event_id" = X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\',"event_created_at" = 1564498626,"event_tags" = \'[]\',"event_content" = \'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\',"event_signature" = X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\',"event_delegator" = NULL,"remote_address" = \'::1\',"expires_at" = NULL where "events"."event_created_at" < 1564498626')
     })
 
     it('replaces event based on event_pubkey, event_kind and event_deduplication', () => {
@@ -498,7 +498,7 @@ describe('EventRepository', () => {
 
       const query = repository.upsert(event).toString()
 
-      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "remote_address") values (\'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\', 1564498626, \'["deduplication"]\', NULL, X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\', 0, X\'55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503\', X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\', \'[]\', \'::1\') on conflict (event_pubkey, event_kind, event_deduplication) WHERE (event_kind = 0 OR event_kind = 3 OR event_kind = 41 OR (event_kind >= 10000 AND event_kind < 20000)) OR (event_kind >= 30000 AND event_kind < 40000) do update set "event_id" = X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\',"event_created_at" = 1564498626,"event_tags" = \'[]\',"event_content" = \'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\',"event_signature" = X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\',"event_delegator" = NULL,"remote_address" = \'::1\' where "events"."event_created_at" < 1564498626')
+      expect(query).to.equal('insert into "events" ("event_content", "event_created_at", "event_deduplication", "event_delegator", "event_id", "event_kind", "event_pubkey", "event_signature", "event_tags", "expires_at", "remote_address") values (\'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\', 1564498626, \'["deduplication"]\', NULL, X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\', 0, X\'55b702c167c85eb1c2d5ab35d68bedd1a35b94c01147364d2395c2f66f35a503\', X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\', \'[]\', NULL, \'::1\') on conflict (event_pubkey, event_kind, event_deduplication) WHERE (event_kind = 0 OR event_kind = 3 OR event_kind = 41 OR (event_kind >= 10000 AND event_kind < 20000)) OR (event_kind >= 30000 AND event_kind < 40000) do update set "event_id" = X\'e527fe8b0f64a38c6877f943a9e8841074056ba72aceb31a4c85e6d10b27095a\',"event_created_at" = 1564498626,"event_tags" = \'[]\',"event_content" = \'{"name":"ottman@minds.io","about":"","picture":"https://feat-2311-nostr.minds.io/icon/1002952989368913934/medium/1564498626/1564498626/1653379539"}\',"event_signature" = X\'d1de98733de2b412549aa64454722d9b66ab3c68e9e0d0f9c5d42e7bd54c30a06174364b683d2c8dbb386ff47f31e6cb7e2f3c3498d8819ee80421216c8309a9\',"event_delegator" = NULL,"remote_address" = \'::1\',"expires_at" = NULL where "events"."event_created_at" < 1564498626')
     })
   })
 })

test/unit/utils/event.spec.ts

@@ -2,6 +2,7 @@ import { expect } from 'chai'
 
 import { CanonicalEvent, Event } from '../../../src/@types/event'
 import {
+  getEventExpiration,
   isDelegatedEvent,
   isDelegatedEventValid,
   isDeleteEvent,
@@ -9,6 +10,7 @@ import {
   isEventIdValid,
   isEventMatchingFilter,
   isEventSignatureValid,
+  isExpiredEvent,
   isParameterizedReplaceableEvent,
   isReplaceableEvent,
   serializeEvent,
@@ -496,3 +498,70 @@ describe('NIP-33', () => {
     })
   })
 })
+describe('NIP-40', () => {
+  let event: Event
+  beforeEach(() => {
+    event = {
+      'id': 'a080fd288b60ac2225ff2e2d815291bd730911e583e177302cc949a15dc2b2dc',
+      'pubkey': '62903b1ff41559daf9ee98ef1ae67cc52f301bb5ce26d14baba3052f649c3f49',
+      'created_at': 1660896109,
+      'kind': 1,
+      'tags': [
+        [
+          'delegation',
+          '86f0689bd48dcd19c67a19d994f938ee34f251d8c39976290955ff585f2db42e',
+          'kind=1&created_at>1640995200',
+          'c33c88ba78ec3c760e49db591ac5f7b129e3887c8af7729795e85a0588007e5ac89b46549232d8f918eefd73e726cb450135314bfda419c030d0b6affe401ec1',
+        ],
+      ],
+      'content': 'Hello world',
+      'sig': 'cd4a3cd20dc61dcbc98324de561a07fd23b3d9702115920c0814b5fb822cc5b7c5bcdaf3fa326d24ed50c5b9c8214d66c75bae34e3a84c25e4d122afccb66eb6',
+    }
+  })
+
+  describe('getEventExpiration', () => {
+    it('returns true if expiration is a safe integer', () => {
+      event.tags = [
+        ['expiration', '160000000'],
+      ]
+      expect(getEventExpiration(event)).to.equal(160000000)
+    })
+
+    it('returns false if event does not have expiration tag', () => {
+      event.tags = []
+      expect(getEventExpiration(event)).to.be.undefined
+    })
+
+    it('returns false if expiration is unsafe integer', () => {
+      event.tags = [
+        ['expiration', '160000000000000000000'],
+      ]
+      expect(getEventExpiration(event)).to.be.undefined
+    })
+
+    it('returns false if expiration is malformed data', () => {
+      event.tags = [
+        ['expiration', 'a'],
+      ]
+      expect(getEventExpiration(event)).to.be.undefined
+    })
+  })
+
+  describe('isExpiredEvent', () => {
+    it('returns false if event does not have tags', () => {
+      event.tags = []
+      expect(isExpiredEvent(event)).to.equal(false)
+    })
+
+    it('returns false if event does not have expiration tags', () => {
+      expect(isExpiredEvent(event)).to.equal(false)
+    })
+
+    it('returns true if event is expired', () => {
+      event.tags = [
+        ['expiration', '100000'],
+      ]
+      expect(isExpiredEvent(event)).to.equal(true)
+    })
+  })
+})