elseif case.rewrite_request_body == true then
            local len = 4
            http_req_call_rewrite.StartBodyVector(builder, len)
            builder:PrependByte(string.byte("\n"))
            builder:PrependByte(string.byte("c"))
            builder:PrependByte(string.byte("b"))
            builder:PrependByte(string.byte("a"))
            local b = builder:EndVector(len)

            http_req_call_rewrite.Start(builder)
            http_req_call_rewrite.AddBody(builder, b)
            local action = http_req_call_rewrite.End(builder)
            build_action(action, http_req_call_action.Rewrite)

=== TEST 27: add route
--- config
    location /t {
        content_by_lua_block {
            local json = require("toolkit.json")
            local t = require("lib.test_admin")

            local code, message, res = t.test('/apisix/admin/routes/1',
                ngx.HTTP_PUT,
                 [[{
                    "uri": "/echo",
                    "plugins": {
                        "ext-plugin-pre-req": {
                        }
                    },
                    "upstream": {
                        "nodes": {
                            "127.0.0.1:1980": 1
                        },
                        "type": "roundrobin"
                    }
                }]]
            )

            if code >= 300 then
                ngx.status = code
                ngx.say(message)
                return
            end

            ngx.say(message)
        }
    }
--- response_body
passed



=== TEST 29: test rewrite request body
--- request
GET /echo
--- response_body chomp
cat
--- extra_stream_config
    server {
        listen unix:$TEST_NGINX_HTML_DIR/nginx.sock;

        content_by_lua_block {
            local ext = require("lib.ext-plugin")
            ext.go({rewrite_request_body = true})
        }
    }
--- response_body
abc