[5.3] add $default parameter to query builder when() method (#15428)

* add a $default parameter to the QB when() clause

allows you to specify a default in the case that the when() $value is false

* add new test for when() method to test $default

* remove extra spaces to make StyleCI happy

* use the correct index for the bindings in the test

* use the full bindings array

src/Illuminate/Database/Query/Builder.php

@@ -459,14 +459,17 @@ public function crossJoin($table, $first = null, $operator = null, $second = nul
      *
      * @param  bool  $value
      * @param  \Closure  $callback
+     * @param  \Closure  $default
      * @return \Illuminate\Database\Query\Builder
      */
-    public function when($value, $callback)
+    public function when($value, $callback, $default = null)
     {
         $builder = $this;
 
         if ($value) {
             $builder = call_user_func($callback, $builder);
+        } elseif ($default) {
+            $builder = call_user_func($default, $builder);
         }
 
         return $builder;

tests/Database/DatabaseQueryBuilderTest.php

@@ -135,6 +135,27 @@ public function testWhenCallback()
         $this->assertEquals('select * from "users" where "email" = ?', $builder->toSql());
     }
 
+    public function testWhenCallbackWithDefault()
+    {
+        $callback = function ($query) {
+            return $query->where('id', '=', 1);
+        };
+
+        $default = function ($query) {
+            return $query->where('id', '=', 2);
+        };
+
+        $builder = $this->getBuilder();
+        $builder->select('*')->from('users')->when(true, $callback, $default)->where('email', 'foo');
+        $this->assertEquals('select * from "users" where "id" = ? and "email" = ?', $builder->toSql());
+        $this->assertEquals([0 => 1, 1 => 'foo'], $builder->getBindings());
+
+        $builder = $this->getBuilder();
+        $builder->select('*')->from('users')->when(false, $callback, $default)->where('email', 'foo');
+        $this->assertEquals('select * from "users" where "id" = ? and "email" = ?', $builder->toSql());
+        $this->assertEquals([0 => 2, 1 => 'foo'], $builder->getBindings());
+    }
+
     public function testBasicWheres()
     {
         $builder = $this->getBuilder();