Add clean code example

README.md

@@ -9,6 +9,7 @@ Here you can find the most **delicious** recipes to cook delicious meals using o
 - [Amazon Web Services (AWS) Elastic Beanstalk](/aws-eb)
 - [AWS SAM](/aws-sam)
 - [Certificates from Let's Encrypt](/autocert)
+- [Clean Code](/clean-code/)
 - [Clean Architecture](/clean-architecture)
 - [Cloud Run](/cloud-run)
 - [Colly Scraping using Fiber and PostgreSQL](/fiber-colly-gorm)

clean-code/.gitignore

@@ -0,0 +1 @@
+db_data

clean-code/Dockerfile-local

@@ -0,0 +1,8 @@
+FROM golang:1.23
+RUN apt update && apt upgrade -y && apt install -y git
+
+WORKDIR /go/src/app
+COPY app ./
+RUN go mod tidy && go mod verify
+
+ENTRYPOINT [ "go", "run", "." ]

clean-code/README.md

@@ -0,0 +1,42 @@
+## Clean code example for Fiber and PostgreSQL
+
+This is an example of a RESTful API built using the Fiber framework (https://gofiber.io/) and PostgreSQL as the database.
+
+### Description of Clean Code
+
+Clean code is a philosophy and set of practices aimed at writing code that is easy to understand, maintain, and extend. Key principles of clean code include:
+
+- **Readability**: Code should be easy to read and understand.
+- **Simplicity**: Avoid unnecessary complexity.
+- **Consistency**: Follow consistent coding standards and conventions.
+- **Modularity**: Break down code into small, reusable, and independent modules.
+- **Testability**: Write code that is easy to test.
+
+This Fiber app is a good example of clean code because:
+
+- **Modular Structure**: The code is organized into distinct modules, making it easy to navigate and understand.
+- **Clear Separation of Concerns**: Different parts of the application (e.g., routes, handlers, services) are clearly separated, making the codebase easier to maintain and extend.
+- **Error Handling**: Proper error handling is implemented to ensure the application behaves predictably.
+
+### Start
+
+1. Build and start the containers:
+    ```sh
+    docker compose up --build
+    ```
+
+1. The application should now be running and accessible at `http://localhost:3000`.
+
+### Endpoints
+
+- `GET /api/v1/books`: Retrieves a list of all books.
+  ```sh
+  curl -X GET http://localhost:3000/api/v1/books
+  ```
+
+- `POST /api/v1/books`: Adds a new book to the collection.
+  ```sh
+  curl -X POST http://localhost:3000/api/v1/books \
+       -H "Content-Type: application/json" \
+       -d '{"title":"Title"}'
+  ```

clean-code/app/config.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"log/slog"
+	"os"
+)
+
+// Configuration is used to store values from environment variables
+type Configuration struct {
+	Port        string
+	DatabaseURL string
+}
+
+// NewConfiguration reads environment variables and returns a new Configuration
+func NewConfiguration() *Configuration {
+	dbURL := getEnvOrDefault("DATABASE_URL", "")
+	if dbURL == "" {
+		slog.Warn("DATABASE_URL is not set")
+	}
+	return &Configuration{
+		Port:        getEnvOrDefault("PORT", "3000"),
+		DatabaseURL: dbURL,
+	}
+}
+
+func getEnvOrDefault(key, defaultValue string) string {
+	if value, exists := os.LookupEnv(key); exists {
+		return value
+	}
+	return defaultValue
+}

clean-code/app/config_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewConfiguration(t *testing.T) {
+	os.Setenv("PORT", "8080")
+	os.Setenv("DATABASE_URL", "postgres://user:pass@localhost:5432/dbname")
+	defer os.Unsetenv("PORT")
+	defer os.Unsetenv("DATABASE_URL")
+
+	conf := NewConfiguration()
+
+	assert.Equal(t, "8080", conf.Port)
+	assert.Equal(t, "postgres://user:pass@localhost:5432/dbname", conf.DatabaseURL)
+}
+
+func TestNewConfiguration_Defaults(t *testing.T) {
+	os.Unsetenv("PORT")
+	os.Unsetenv("DATABASE_URL")
+
+	conf := NewConfiguration()
+
+	assert.Equal(t, "3000", conf.Port)
+	assert.Equal(t, "", conf.DatabaseURL)
+}
+
+func TestGetEnvOrDefault(t *testing.T) {
+	os.Setenv("TEST_ENV", "value")
+	defer os.Unsetenv("TEST_ENV")
+
+	value := getEnvOrDefault("TEST_ENV", "default")
+	assert.Equal(t, "value", value)
+
+	value = getEnvOrDefault("NON_EXISTENT_ENV", "default")
+	assert.Equal(t, "default", value)
+}

clean-code/app/datasources/data_sources.go

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+package datasources
+
+import "app/datasources/database"
+
+// DataSources is a struct that contains all the data sources
+// It is used to pass different data sources to the server and services
+type DataSources struct {
+	DB database.Database
+}

clean-code/app/datasources/database/db.go

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+package database
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"strings"
+)
+
+// Book represents a book in the database
+type Book struct {
+	ID    int
+	Title string
+}
+
+// NewBook represents a new book to be created to the database
+type NewBook struct {
+	Title string
+}
+
+// Database defines the interface for interacting with the book database.
+// Using this interface allows changing the implementation without affecting the rest of the code.
+type Database interface {
+	// LoadAllBooks retrieves all books from the database.
+	LoadAllBooks(ctx context.Context) ([]Book, error)
+
+	// CreateBook adds a new book to the database.
+	CreateBook(ctx context.Context, newBook NewBook) error
+
+	// CloseConnections closes all open connections to the database.
+	CloseConnections()
+}
+
+// NewDatabase creates a new Database instance
+func NewDatabase(ctx context.Context, databaseURL string) (Database, error) {
+	if databaseURL == "" {
+		slog.Info("Using in-memory database implementation")
+		return newMemoryDB(), nil
+	}
+
+	if strings.HasPrefix(databaseURL, "postgres://") {
+		db, err := newPostgresDB(ctx, databaseURL)
+		if err != nil {
+			return nil, fmt.Errorf("failed to initialize PostgreSQL database connection: %w", err)
+		}
+		slog.Info("Using PostgreSQL database implementation")
+		return db, nil
+	}
+
+	return nil, fmt.Errorf("unsupported database URL scheme: %s", databaseURL)
+}

clean-code/app/datasources/database/db_mock.go

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+package database
+
+import (
+	"context"
+
+	"github.com/stretchr/testify/mock"
+)
+
+type DatabaseMock struct {
+	mock.Mock
+}
+
+func (m *DatabaseMock) LoadAllBooks(ctx context.Context) ([]Book, error) {
+	args := m.Called(ctx)
+	if args.Get(0) == nil {
+		return nil, args.Error(1)
+	}
+	return args.Get(0).([]Book), args.Error(1)
+}
+
+func (m *DatabaseMock) CreateBook(ctx context.Context, newBook NewBook) error {
+	args := m.Called(ctx, newBook)
+	return args.Error(0)
+}
+
+func (m *DatabaseMock) CloseConnections() {
+}

clean-code/app/datasources/database/db_test.go

@@ -0,0 +1,34 @@
+package database
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewDatabase_MemoryDB(t *testing.T) {
+	ctx := context.Background()
+	db, err := NewDatabase(ctx, "")
+	assert.Nil(t, err)
+	assert.Equal(t, "*database.memoryDB", reflect.TypeOf(db).String())
+}
+
+func TestNewDatabase_PostgresDB(t *testing.T) {
+	ctx := context.Background()
+	db, err := NewDatabase(ctx, "postgres://localhost:5432")
+	assert.Nil(t, err)
+	assert.Equal(t, "*database.postgresDB", reflect.TypeOf(db).String())
+}
+
+func TestNewDatabase_InvalidDatabaseConfiguration(t *testing.T) {
+	ctx := context.Background()
+	_, err := NewDatabase(ctx, "invalid")
+	assert.ErrorContains(t, err, "unsupported database")
+}
+
+func assertBook(t *testing.T, book Book, expectedID int, expected NewBook) {
+	assert.Equal(t, expectedID, book.ID)
+	assert.Equal(t, expected.Title, book.Title)
+}

clean-code/app/datasources/database/memory_db.go

@@ -0,0 +1,32 @@
+package database
+
+import "context"
+
+// This is just an example and not for production use
+func newMemoryDB() Database {
+	return &memoryDB{
+		records:   make([]Book, 0, 10),
+		idCounter: 0,
+	}
+}
+
+type memoryDB struct {
+	records   []Book
+	idCounter int
+}
+
+func (db *memoryDB) LoadAllBooks(_ context.Context) ([]Book, error) {
+	return db.records, nil
+}
+
+func (db *memoryDB) CreateBook(_ context.Context, newBook NewBook) error {
+	db.records = append(db.records, Book{
+		ID:    db.idCounter,
+		Title: newBook.Title,
+	})
+	db.idCounter++
+	return nil
+}
+
+func (db *memoryDB) CloseConnections() {
+}

clean-code/app/datasources/database/memory_db_test.go

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+package database
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMemoryDB_LoadBooks(t *testing.T) {
+	db := newMemoryDB()
+	books, err := db.LoadAllBooks(context.Background())
+	assert.Nil(t, err)
+	assert.Equal(t, 0, len(books))
+}
+
+func TestMemoryDB_SaveBook(t *testing.T) {
+	db := newMemoryDB()
+	newBook := NewBook{Title: "Title"}
+	err := db.CreateBook(context.Background(), newBook)
+	assert.Nil(t, err)
+
+	books, err := db.LoadAllBooks(context.Background())
+	assert.Nil(t, err)
+	assert.Equal(t, 1, len(books))
+	assertBook(t, books[0], 0, newBook)
+}
+
+func TestMemoryDB_SaveBookMultiple(t *testing.T) {
+	db := newMemoryDB()
+	newBook1 := NewBook{Title: "Title1"}
+	err := db.CreateBook(context.Background(), newBook1)
+	assert.Nil(t, err)
+
+	newBook2 := NewBook{Title: "Title2"}
+	err = db.CreateBook(context.Background(), newBook2)
+	assert.Nil(t, err)
+
+	books, err := db.LoadAllBooks(context.Background())
+	assert.Nil(t, err)
+	assert.Equal(t, 2, len(books))
+	assertBook(t, books[0], 0, newBook1)
+	assertBook(t, books[1], 1, newBook2)
+}