[question]running tests fail

hi,
I run the example in https://openresty.gitbooks.io/programming-openresty/content/testing/running-tests.html, then get this failed result:

t/foo.t .. 
ok 1 - TEST 1: hello, world - status code ok
not ok 2 - TEST 1: hello, world - response_body - response is expected (repeated req 0, req 0)

#   Failed test 'TEST 1: hello, world - response_body - response is expected (repeated req 0, req 0)'
#   at /Library/Perl/5.18/Test/Nginx/Socket.pm line 1387.
#          got: "hello, world!\x{0a}"
#       length: 14
#     expected: "hello, world!\x{0a}--- error_code: 200"
#       length: 33
#     strings begin to differ at char 15 (line 2 column 1)
1..2
# Looks like you failed 1 test of 2.
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/2 subtests 

Test Summary Report
-------------------
t/foo.t (Wstat: 256 Tests: 2 Failed: 1)
  Failed test:  2
  Non-zero exit status: 1
Files=1, Tests=2,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.12 cusr  0.04 csys =  0.18 CPU)
Result: FAIL

I don't know what's the reason, please help me fix it.
Thank you!

Start with the running-tests example linked in the issue and inspect t/foo.t alongside the failure at Test::Nginx::Socket.pm line 1387. Compare the expected response with the actual output and verify the local test setup; done means the example completes without the failed response_body assertion.