Fixed leading slash when the base url is empty

Author: Sammyjo20

src/Helpers/URLHelper.php

@@ -34,7 +34,11 @@ public static function join(string $baseUrl, string $endpoint): string
         $requiresTrailingSlash = ! empty($endpoint) && $endpoint !== '/';
 
         $baseEndpoint = rtrim($baseUrl, '/ ');
-        $baseEndpoint = $requiresTrailingSlash ? $baseEndpoint . '/' : $baseEndpoint;
+
+        $endpointIsNotUrl = empty(filter_var($endpoint, FILTER_VALIDATE_URL));
+        $glue = $endpointIsNotUrl ? '/' : null;
+
+        $baseEndpoint = $requiresTrailingSlash ? $baseEndpoint . $glue : $baseEndpoint;
 
         return $baseEndpoint . $endpoint;
     }

tests/Unit/URLHelperTest.php

@@ -0,0 +1,15 @@
+<?php
+
+use Sammyjo20\Saloon\Helpers\URLHelper;
+
+test('the URL helper will join two URLs together', function ($baseUrl, $endpoint, $expected) {
+    expect(URLHelper::join($baseUrl, $endpoint))->toEqual($expected);
+})->with([
+    ['https://google.com', '/search', 'https://google.com/search'],
+    ['https://google.com', 'search', 'https://google.com/search'],
+    ['https://google.com/', '/search', 'https://google.com/search'],
+    ['https://google.com/', 'search', 'https://google.com/search'],
+    ['https://google.com//', '//search', 'https://google.com/search'],
+    ['', 'https://google.com/search', 'https://google.com/search'],
+    ['', 'google.com/search', '/google.com/search'],
+]);