Tests that non-utf8 content is returned base64-encoded

Running test: bound runTestCase
data: 9eXr6+7z base64: true

Running test: bound runTestCase
data: Hello base64: false

Running test: bound runTestCase
data: Hello base64: false

Running test: bound runTestCase
data: QYvK9TIXnCdasXe2xNs59eggusc= base64: true

Running test: bound runTestCase
data: MTIzNDU2Nzg5MTIzNDU2Nzg54KA= base64: true

Running test: bound runTestCase
data: 123456789123456789ࠀ base64: false