Step 9.4: Add Mutation.removeChat

schema/resolvers.ts

@@ -153,6 +153,30 @@ const resolvers: Resolvers = {
 
       return chat;
     },
+
+    removeChat(root, { chatId }, { currentUser }) {
+      if (!currentUser) return null;
+
+      const chatIndex = chats.findIndex(c => c.id === chatId);
+
+      if (chatIndex === -1) return null;
+
+      const chat = chats[chatIndex];
+
+      if (!chat.participants.some(p => p === currentUser.id)) return null;
+
+      chat.messages.forEach(chatMessage => {
+        const chatMessageIndex = messages.findIndex(m => m.id === chatMessage);
+
+        if (chatMessageIndex !== -1) {
+          messages.splice(chatMessageIndex, 1);
+        }
+      });
+
+      chats.splice(chatIndex, 1);
+
+      return chatId;
+    },
   },
 
   Subscription: {

schema/typeDefs.graphql

@@ -34,6 +34,7 @@ type Query {
 type Mutation {
   addMessage(chatId: ID!, content: String!): Message
   addChat(recipientId: ID!): Chat
+  removeChat(chatId: ID!): ID
 }
 
 type Subscription {

tests/mutations/removeChat.test.ts

@@ -0,0 +1,52 @@
+import { createTestClient } from 'apollo-server-testing';
+import { ApolloServer, PubSub, gql } from 'apollo-server-express';
+import schema from '../../schema';
+import { resetDb, users } from '../../db';
+
+describe('Mutation.removeChat', () => {
+  beforeEach(resetDb);
+
+  it('removes chat by id', async () => {
+    const server = new ApolloServer({
+      schema,
+      context: () => ({
+        pubsub: new PubSub(),
+        currentUser: users[0],
+      }),
+    });
+
+    const { query, mutate } = createTestClient(server);
+
+    const addChatRes = await mutate({
+      variables: { chatId: '1' },
+      mutation: gql`
+        mutation RemoveChat($chatId: ID!) {
+          removeChat(chatId: $chatId)
+        }
+      `,
+    });
+
+    expect(addChatRes.data).toBeDefined();
+    expect(addChatRes.errors).toBeUndefined();
+    expect(addChatRes.data!.removeChat).toEqual('1');
+
+    const getChatRes = await query({
+      variables: { chatId: '1' },
+      query: gql`
+        query GetChat($chatId: ID!) {
+          chat(chatId: $chatId) {
+            id
+            name
+            participants {
+              id
+            }
+          }
+        }
+      `,
+    });
+
+    expect(addChatRes.data).toBeDefined();
+    expect(getChatRes.errors).toBeUndefined();
+    expect(addChatRes.data!.chat).toBeUndefined();
+  });
+});