[5.4] add tap to query builder (#18284)

* add tap to query builder

* formatting mistake

* formatting correction

src/Illuminate/Database/Query/Builder.php

@@ -478,6 +478,17 @@ public function when($value, $callback, $default = null)
         return $builder;
     }
 
+    /**
+     * Pass the query to a given callback.
+     *
+     * @param  \Closure  $callback
+     * @return \Illuminate\Database\Query\Builder
+     */
+    public function tap($callback)
+    {
+        return $this->when(true, $callback);
+    }
+
     /**
      * Merge an array of where clauses and bindings.
      *

tests/Database/DatabaseQueryBuilderTest.php

@@ -166,6 +166,17 @@ public function testWhenCallbackWithDefault()
         $this->assertEquals([0 => 2, 1 => 'foo'], $builder->getBindings());
     }
 
+    public function testTapCallback()
+    {
+        $callback = function ($query) {
+            return $query->where('id', '=', 1);
+        };
+
+        $builder = $this->getBuilder();
+        $builder->select('*')->from('users')->tap($callback)->where('email', 'foo');
+        $this->assertEquals('select * from "users" where "id" = ? and "email" = ?', $builder->toSql());
+    }
+
     public function testBasicWheres()
     {
         $builder = $this->getBuilder();