Create src files and test files in two separated directories in Golang

My Golang project files hierarchy be like:

.
├── src
│   └── sum.go
└── test
    └── sum_test.go

sum.go:

package sum

func Sum(a, b int) int {
    return a + b
}

sum_test.go:

import "testing"

func AssertEqual(t *testing.T, first interface{}, second interface{}) {
    if first != second {
        t.Errorf("Expected %+v, got: %+v", first, second)
    }
}

func TestSum(t *testing.T) {
    AssertEqual(t, Sum(2, 2), 4)
}

Once I run go test ./... in the root of the project (the directory above src and test), the output is:

# _/home/shayan/bench/gotest/test [_/home/shayan/bench/gotest/test.test]
test/sum_test.go:12:17: undefined: Sum
?       _/home/shayan/bench/gotest/src  [no test files]
FAIL    _/home/shayan/bench/gotest/test [build failed]
FAIL

I also have seen the following questions:

Golang tests in sub-directory

How to go test all testings in my project?

Could anyone correct me if it's possible to have src files separated from test files in two directories like above?