Added function to re-enable proration after it was disabled

src/Subscription.php

@@ -311,6 +311,18 @@ public function noProrate()
         return $this;
     }
 
+    /**
+     * Indicate that the plan change should be prorated.
+     *
+     * @return $this
+     */
+    public function prorate()
+    {
+        $this->prorate = true;
+
+        return $this;
+    }
+
     /**
      * Change the billing cycle anchor on a plan change.
      *

tests/Integration/CashierTest.php

@@ -627,6 +627,44 @@ public function test_subscription_state_scopes()
         $this->assertTrue($user->subscriptions()->ended()->exists());
     }
 
+    public function test_subscription_proration()
+    {
+        $user = User::create([
+            'email' => 'taylor@laravel.com',
+            'name' => 'Taylor Otwell',
+        ]);
+
+        $subscription = $user->newSubscription('main', static::$premiumPlanId)
+            ->create($this->getTestToken());
+
+        $invoice = $user->invoices()[0];
+
+        $this->assertEquals('$20.00', $invoice->total(), 'Invoice for premium plan should bill $20.00');
+
+        // swapping from premium ($20/month) to normal ($10/month)
+        // without proration should invoice $20
+        $subscription
+            ->noProrate()
+            ->swap(static::$planId);
+
+        $invoice = $user->invoices()[0];
+
+        $this->assertEquals('$20.00', $invoice->total(), 'Swapping from premium to cheaper plan without proration should not change the invoice amount.');
+
+        // swapping from premium ($20/month) to normal ($10/month)
+        // with proration should invoice $0
+        $subscription
+            ->swap(static::$premiumPlanId);
+
+        $subscription
+            ->prorate()
+            ->swap(static::$planId);
+
+        $invoice = $user->invoices()[0];
+
+        $this->assertEquals('$0.00', $invoice->total(), 'Swapping from premium to cheaper plan with proration should change the invoice amount.');
+    }
+
     public function test_update_stripe_customer()
     {
         $user = User::create([