diff --git a/test/supports/mock_env_helper.rb b/test/supports/mock_env_helper.rb
index d4607296a51..9dfba9f3989 100644
--- a/test/supports/mock_env_helper.rb
+++ b/test/supports/mock_env_helper.rb
@@ -1,13 +1,8 @@
 # frozen_string_literal: true
 
 module MockEnvHelper
-  def mock_env(partial_env_hash)
-    old = ENV.to_hash
-    ENV.update partial_env_hash
-    begin
-      yield
-    ensure
-      ENV.replace old
-    end
+  def mock_env(hash_for_mock, &block)
+    env_hash = ENV.to_hash.merge(hash_for_mock)
+    ENV.stub(:[], ->(key) { env_hash[key] }, &block)
   end
 end