go-by-test/blogposts/blogposts_test.go

package blogposts

import (
	"reflect"
	"testing"
	"testing/fstest"
)

// NOTE: This should be a black box test outside blogposts package.

// NOTE: If we want to test the return error
//
// type StubFailingFS struct{}
//
// func (s StubFailingFS) Open(name string) (fs.File, error) {
// 	return nil, errors.New("fail")
// }

func TestNewBlogPosts(t *testing.T) {
	const (
		firstBody = `Title: Post 1
Description: Description 1
Tags: tdd, go
---
Hello
World`
		secondBody = `Title: Post 2
Description: Description 2
Tags: rust, borrow-checker
---
B
L
M`
	)

	fs := fstest.MapFS{
		"hello world.md":  {Data: []byte(firstBody)},
		"hello-world2.md": {Data: []byte(secondBody)},
	}

	posts, err := NewPostsFromFS(fs)
	if err != nil {
		t.Fatal(err)
	}

	if len(posts) != len(fs) {
		t.Errorf("got %d posts, wanted %d posts", len(posts), len(fs))
	}

	assertPost(t, posts[0], Post{
		Title:       "Post 1",
		Description: "Description 1",
		Tags:        []string{"tdd", "go"},
		Body: `Hello
World`,
	})
}

func TestWrongFile(t *testing.T) {
	fs := fstest.MapFS{
		"hello world.txt": {Data: []byte("Yolo")},
	}

	_, err := NewPostsFromFS(fs)
	if err == nil {
		t.Errorf("should be an error but not")
	}
}

func assertPost(t testing.TB, got Post, want Post) {
	t.Helper()
	if !reflect.DeepEqual(got, want) {
		t.Errorf("got %+v, want %+v", got, want)
	}
}