Fix multiple enable/disable

Author: GromNaN

src/Connection.php

@@ -143,16 +143,20 @@ public function enableQueryLog()
     {
         parent::enableQueryLog();
 
-        $this->commandSubscriber = new CommandSubscriber($this);
-        $this->connection->addSubscriber($this->commandSubscriber);
+        if (! $this->commandSubscriber) {
+            $this->commandSubscriber = new CommandSubscriber($this);
+            $this->connection->addSubscriber($this->commandSubscriber);
+        }
     }
 
     public function disableQueryLog()
     {
-        parent::disableQueryLog(); // TODO: Change the autogenerated stub
+        parent::disableQueryLog();
 
-        $this->connection->removeSubscriber($this->commandSubscriber);
-        $this->commandSubscriber = null;
+        if ($this->commandSubscriber) {
+            $this->connection->removeSubscriber($this->commandSubscriber);
+            $this->commandSubscriber = null;
+        }
     }
 
     protected function withFreshQueryLog($callback)

tests/ConnectionTest.php

@@ -287,9 +287,19 @@ public function testDisableQueryLog()
         DB::table('items')->get();
         $this->assertCount(1, DB::getQueryLog());
 
+        // Enable twice should only log once
+        DB::enableQueryLog();
+        DB::table('items')->get();
+        $this->assertCount(2, DB::getQueryLog());
+
         DB::disableQueryLog();
         DB::table('items')->get();
-        $this->assertCount(1, DB::getQueryLog());
+        $this->assertCount(2, DB::getQueryLog());
+
+        // Disable twice should not log
+        DB::disableQueryLog();
+        DB::table('items')->get();
+        $this->assertCount(2, DB::getQueryLog());
     }
 
     public function testSchemaBuilder()