app_test.go

package app

import (
	"context"
	"flag"
	"reflect"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

type CLIOption struct {
	configFile string
}

func ParseCLI() (*CLIOption, error) {
	configFile := flag.String("config", "~/.appconfig", "path to the config file")
	flag.Parse()

	return &CLIOption{*configFile}, nil
}

type Config struct {
	DatabaseHost string
}

func BuildConfig(cliOption *CLIOption) *Config {
	// use cliOption.configFile to load the config
	return &Config{
		DatabaseHost: "127.0.0.1",
	}
}

type Database struct{}

func NewDatabase(cfg *Config) *Database {
	return &Database{}
}

func (d *Database) Run(ctx context.Context) error {
	log("database has started")
	<-ctx.Done()
	log("database has stopped")
	return nil
}

type Server struct{}

func NewServer(cfg *Config, cli *CLIOption, db *Database) *Server {
	return &Server{}
}

func NewServerBase() *Server {
	return &Server{}
}

func (s *Server) Run(ctx context.Context) error {
	log("server is doing something")
	<-ctx.Done()
	log("server has stopped")
	return nil
}

func Test_App(t *testing.T) {
	ctx := context.Background()
	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
	defer cancel()

	a := New()
	a.AddProvider(ParseCLI)
	a.AddProvider(BuildConfig)
	a.AddRunnable(NewDatabase)
	a.AddRunnable(NewServer)
	err := a.Run(ctx)
	require.NoError(t, err)
}

gistfile1.txt

=== RUN   Test_App
building services:  [{*app.Database} {*app.Server}]
building:  {*app.Database}
calling provider:  github.com/pior/app.NewDatabase
calling provider:  github.com/pior/app.BuildConfig
calling provider:  github.com/pior/app.ParseCLI
building:  {*app.Server}
calling provider:  github.com/pior/app.NewServer
found value in cache:  {*app.Config}
found value in cache:  {*app.CLIOption}
found value in cache:  {*app.Database}
starting:  {*app.Database}
found value in cache:  {*app.Database}
starting:  {*app.Server}
found value in cache:  {*app.Server}
started runnable:  *app.Server
server is doing something
started runnable:  *app.Database
database has started
context cancelled, starting shutdown
server has stopped
component &{} returned:  [<error Value>]
database has stopped
component &{} returned:  [<error Value>]
--- PASS: Test_App (3.00s)
PASS
ok  	github.com/pior/app	3.227s