Allow client instance instead of configuration

docs/configuration.md

@@ -2,24 +2,25 @@
 
 ### connectionConfig
 
-- Type: `object`
+- Type: `object | Client | Pool`
 - Default: `null`
 - Required: `true`
 
-Connection configuration object for [node-postgres](https://node-postgres.com/features/connecting#programmatic)
+Connection configuration object for [node-postgres](https://node-postgres.com/features/connecting#programmatic).
+It can be an existing `pg.Client` or `pg.Pool` instance, too.
 
 ### defaultSchema
 
 - Type: `string`
 - Default: `'public'`
 - Required: `false`
 
-It will be used in objects whose names do not contain a schema name
+It will be used in objects whose names do not contain a schema name.
 
 ### logging
 
 - Type: `boolean | function`
 - Default: `console.info`
 - Required: `false`
 
-Option to enable logging in the console or callback of the format `function(...messages) {}` for displaying a message about changes
+Option to enable logging in the console or callback of the format `function(...messages) {}` for displaying a message about changes.

lib/connection-manager.js

@@ -6,10 +6,13 @@
  */
 'use strict';
 
-const { Client } = require('pg');
+const { Client, Pool } = require('pg');
 
 class ConnectionManager {
   static getClient(config) {
+    if (config instanceof Client || config instanceof Pool) {
+      return config;
+    }
     return new Client(config);
   }
 

types/index.d.ts

@@ -5,6 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import { Client, Pool } from 'pg';
+
 interface ReferenceOptions {
   table: string;
   columns: string[];
@@ -127,7 +129,7 @@ interface ImportOptions {
 }
 
 interface DifferOptions {
-  connectionConfig: object;
+  connectionConfig: object | Client | Pool;
   defaultSchema?: string;
   logging?: boolean | Function;
 }