test(client-s3): attempt to add e2e test

Author: AllanZhengYP

clients/client-s3/karma.conf.js

@@ -60,6 +60,12 @@ module.exports = function (config) {
     logLevel: config.LOG_WARN,
     autoWatch: false,
     browsers: ["ChromeHeadless", "FirefoxHeadless"],
+    customLaunchers: {
+      FirefoxHeadless: {
+        base: "Firefox",
+        flags: ["-headless"]
+      }
+    },
     singleRun: true,
     concurrency: Infinity,
     exclude: ["**/*.d.ts", "*.spec.ts"]