diff --git a/tests/AuthHeaderTest.php b/tests/AuthHeaderTest.php
index 3f39327..11dec73 100644
--- a/tests/AuthHeaderTest.php
+++ b/tests/AuthHeaderTest.php
@@ -24,7 +24,7 @@ it('sort query parameters', function () {
 it('get sorted query params as string value', function () {
 
     $digestedParam = Header::digestQueryParameters([]);
-    expect($digestedParam)->toBeNull();
+    expect($digestedParam)->toBeEmpty();
 
     $params = [
         'z_index' => 'z_value',
diff --git a/tests/ChangeLeverageTest.php b/tests/ChangeLeverageTest.php
index 4db10c8..b23c2d5 100644
--- a/tests/ChangeLeverageTest.php
+++ b/tests/ChangeLeverageTest.php
@@ -2,6 +2,15 @@
 
 use Msr\LaravelBitunixApi\Requests\ChangeLeverageRequestContract;
 
+beforeEach(function () {
+    config([
+        'bitunix-api.future_base_uri' => 'https://fapi.bitunix.com/',
+        'bitunix-api.api_key' => 'test-api-key',
+        'bitunix-api.api_secret' => 'test-secret-key',
+        'bitunix-api.language' => 'en-US',
+    ]);
+});
+
 it('can change leverage successfully', function () {
     $api = app(ChangeLeverageRequestContract::class);
     // This test will make a real API call if credentials are valid