Types: Actually add "pg" property to FastifyInstance (semi-breaking)

README.md

@@ -238,18 +238,6 @@ Install the compiler and typings for pg module:
 npm install --save-dev typescript @types/pg
 ```
 
-Add the `pg` property to `FastifyInstance`. Like this if you use an unnamed instance:
-
-```typescript
-import type { PostgresDb } from 'fastify-postgres';
-
-declare module 'fastify' {
-  export interface FastifyInstance {
-    pg: PostgresDb;
-  }
-}
-```
-
 More examples in the [examples/typescript](./examples/typescript) directory.
 
 ## Development and Testing

index.d.ts

@@ -37,5 +37,11 @@ type PostgresPluginOptions = {
 
 declare const fastifyPostgres: FastifyPluginCallback<PostgresPluginOptions>;
 
+declare module 'fastify' {
+  export interface FastifyInstance {
+    pg: PostgresDb & Record<string, PostgresDb>;
+  }
+}
+
 export { fastifyPostgres, PostgresDb, PostgresPluginOptions };
 export default fastifyPostgres;

test/types/initialization.test-d.ts

@@ -1,7 +1,8 @@
 import fastify from 'fastify';
 import * as pg from 'pg';
+import { expectAssignable, expectType } from 'tsd';
 
-import fastifyPostgres from '../../index';
+import fastifyPostgres, { PostgresDb } from '../../index';
 
 const app = fastify();
 
@@ -30,3 +31,9 @@ app.register(fastifyPostgres, {
 app.register(fastifyPostgres, {
   connectionString: 'postgres://user:password@host:port/db',
 });
+
+// Plugin property available
+app.after(() => {
+  expectAssignable<PostgresDb>(app.pg);
+  expectType<PostgresDb>(app.pg.users);
+});

test/types/query.test-d.ts

@@ -1,6 +1,6 @@
 import fastify from 'fastify';
 import { Client, Pool, PoolClient, QueryResult } from 'pg';
-import { expectType } from 'tsd';
+import { expectAssignable, expectType } from 'tsd';
 
 import fastifyPostgres, { PostgresDb } from '../../index';
 
@@ -10,14 +10,8 @@ app.register(fastifyPostgres, {
   connectionString: 'postgres://user:password@host:port/db',
 });
 
-declare module 'fastify' {
-  export interface FastifyInstance {
-    pg: PostgresDb;
-  }
-}
-
 app.get('/calc', async () => {
-  expectType<PostgresDb>(app.pg);
+  expectAssignable<PostgresDb>(app.pg);
 
   expectType<Pool>(app.pg.pool);
   expectType<Client>(app.pg.Client);

test/types/transaction.test-d.ts

@@ -10,12 +10,6 @@ app.register(fastifyPostgres, {
   connectionString: 'postgres://user:password@host:port/db',
 });
 
-declare module 'fastify' {
-  export interface FastifyInstance {
-    pg: PostgresDb;
-  }
-}
-
 app.post('/insert-async', async () => {
   const insertQuery = `
     INSERT INTO routes(name)