[short] skip

go test -trimpath -v .
! stdout '[/\\]pkg_test[/\\]'
stdout -count=3 '[/\\]pkg[/\\]'

-- go.mod --
module example.com/pkg

go 1.17

-- pkg.go --
package pkg

import "runtime"

func PrintFile() {
	_, file, _, _ := runtime.Caller(0)
	println(file)
}

-- pkg_test.go --
package pkg

import "runtime"

func PrintFileForTest() {
	_, file, _, _ := runtime.Caller(0)
	println(file)
}

-- pkg_x_test.go --
package pkg_test

import (
	"runtime"
	"testing"

	"example.com/pkg"
)

func TestMain(m *testing.M) {
	pkg.PrintFile()
	pkg.PrintFileForTest()
	PrintFileInXTest()
}

func PrintFileInXTest() {
	_, file, _, _ := runtime.Caller(0)
	println(file)
}