如何为REST服务生成代码覆盖率

Question

I want to get test coverage of a REST service written in Go. I am spawning REST service through a goroutine, then making HTTP requests using rest client, and reviewing the HTTP responses. Tests are passing successfully but go test -cover returns 0% test coverage. Is there a way to get the actual test coverage of all the packages used inside the go lang REST service.

my test file: main_test.go

import (
    "testing"
)

// Test started when the test binary is started. Only calls main.
func TestSystem(t *testing.T) {
    go main()    // Spinning up the go lang REST server in a separate go routine.
    http.Post("https://localhost/do_something")
}

my output:

go test -cover  main_test.go
ok      command-line-arguments  0.668s  coverage: 0.0% of statements 

Answer 1

Regardless of the root cause, I think there’s an issue with your general approach here.

I would suggest that some of what you’re testing here isn’t your code and you shouldn’t bother. You don’t need to actually test the http protocol and http package, right?

So the way I’ve handled this in the past is to break apart my the meaningful code that I want to test out of the http handler functions. The http handlers should only be responsible for validating input, calling the actual business logic, and then formatting output.

Once you’ve broken apart your code this way, you can directly call your meaningful functions from your tests. Your http handler functions should be so simple that there is no place for bugs to lurk.

Don’t seek 100% test coverage. Test what matters.