test: private-key with escaped newlines

Author: gr2m

tests/main-private-key-with-escaped-newlines.js

@@ -0,0 +1,6 @@
+import { test, DEFAULT_ENV } from "./main.js";
+
+// Verify `main` successfully obtains a token when the `owner` input is not set, but the `repositories` input is set.
+await test(() => {
+  process.env['INPUT_PRIVATE-KEY'] = DEFAULT_ENV.PRIVATE_KEY.replace(/\n/g, '\\n')
+});