[10.x] Use fallback when previous URL is the same as the current (#46234)

* fallback when previous URL is the same as the current

* do not check fallback

Author: rodrigopedra

src/Illuminate/Routing/UrlGenerator.php

@@ -158,7 +158,7 @@ public function previous($fallback = false)
 
         $url = $referrer ? $this->to($referrer) : $this->getPreviousUrlFromSession();
 
-        if ($url) {
+        if ($url && rtrim($url, '/') !== $this->request->fullUrl()) {
             return $url;
         } elseif ($fallback) {
             return $this->to($fallback);

tests/Routing/RoutingUrlGeneratorTest.php

@@ -734,6 +734,32 @@ public function testPreviousPath()
         $this->assertSame('/bar', $url->previousPath('/bar'));
     }
 
+    public function testWhenPreviousIsEqualToCurrent()
+    {
+        $url = new UrlGenerator(
+            new RouteCollection,
+            Request::create('http://www.foo.com/')
+        );
+
+        $url->getRequest()->headers->set('referer', 'http://www.foo.com/');
+        $this->assertSame('http://www.foo.com', $url->previous());
+        $this->assertSame('http://www.foo.com/bar', $url->previous('/bar'));
+
+        $url->setRequest(Request::create('http://www.foo.com/bar'));
+
+        $url->getRequest()->headers->set('referer', 'http://www.foo.com/bar');
+        $this->assertSame('http://www.foo.com', $url->previous());
+        $this->assertSame('http://www.foo.com/bar', $url->previous('/bar'));
+        $this->assertSame('http://www.foo.com/baz', $url->previous('/baz'));
+
+        $url->setRequest(Request::create('http://www.foo.com/bar?page=2'));
+
+        $url->getRequest()->headers->set('referer', 'http://www.foo.com/bar?page=2');
+        $this->assertSame('http://www.foo.com', $url->previous());
+        $this->assertSame('http://www.foo.com/bar', $url->previous('/bar'));
+        $this->assertSame('http://www.foo.com/bar?page=2', $url->previous('/bar?page=2'));
+    }
+
     public function testRouteNotDefinedException()
     {
         $this->expectException(RouteNotFoundException::class);