Go module package not found when executing the tests

I know I am lacking a fundamental understanding how Go is seeking for a package, but let me just emphasize my thoughts and if needed - you could downvote.

This is my structure of the Go module:

├── go.mod

├── gopher.json

├── main.go

├── story.go

├── template.html

└── tests

   ├── cyow_test.go
   └── gopher.json

Nothing too outside of the straightforward, dedicated /tests directory where the tests are supposed to be placed.

This is my cyow_test.go file:

import (
	"io/ioutil"
	"story"
	"testing"
)

func TestUnmarshallOverStoryStruct(t *testing.T) {
	t.Parallel()
	content, fileError := ioutil.ReadFile("gopher.json")
	if fileError != nil {
		t.Error("The file for Chapter is not found.")
	}

	story := story.Story{}
	fmt.Println("Story has been initialized")

	err := json.Unmarshal([]byte(content), &story)
	fmt.PRintln("Json unmarshall statement has been executed.")
	if err != nil {
		panic(err)
	}
}

You could ignore the function, it's mainly for some learning purposes. The important part is that I am relying on a story package, which has been declared as part of the module.

When I go inside /tests and run 'go test' I receive:

cyow_test.go:5:2: package story is not in GOROOT (/usr/local/go/src/story)

I have ran 'go mod tidy' inside the module root directory and my simple questions are:

1. Why Go does not find out the package by default ? It's a package part of the module, so it schould come natively - this is my assumption.
2. Does that mean that the only way to refer to packages ( even inside your module ) is to reference them through a remote repo URL, like github.com ... or eventually just copy the package to /usr/local/go/src ( which is not friendly at all )

Your assumption is wrong. The way to import a package is 'module/package'. The module name does not have to include a repository name. Do not copy packages to go source directory.