Added check for duplicate connection name

Author: cemremengu

index.js

@@ -29,6 +29,10 @@ function fastifyPostgres (fastify, options, next) {
       fastify.decorate('pg', {})
     }
 
+    if (fastify.pg[name]) {
+      return next(new Error('Connection name has already been registered: ' + name))
+    }
+
     fastify.pg[name] = db
   } else {
     if (fastify.pg) {

test.js

@@ -234,3 +234,21 @@ test('fastify.pg.test use native module', t => {
       })
   })
 })
+
+test('fastify.pg.test should throw with duplicate connection names', t => {
+  t.plan(1)
+
+  const fastify = Fastify()
+
+  fastify.register(fastifyPostgres, {
+    name: 'test',
+    connectionString: 'postgres://postgres@localhost/postgres'
+  })
+
+  t.throws(fastify.register(fastifyPostgres, {
+    name: 'test',
+    connectionString: 'postgres://postgres@localhost/postgres'
+  }),
+  new Error('Connection name has already been registered: test'),
+  'should throw')
+})