The test is not yet automated, so you need to set up an environment manually to test it.
Create a TiDB cluster with 2 TiDB servers on localhost. One server listen on port 4001 and another on 4002, then execute go test in this folder to run the test.
You are expected to see 2 tests passed.
$ go test
OK: 2 passed
PASS
ok github.com/pingcap/tidb/tests/readonlytest 2.150s