cast/merge_test.go

package cast_test

import (
	"testing"
	"apigo.cc/go/cast"
)

type DBConfig struct {
	Host string
	Port int
}

func TestMapStructMerge(t *testing.T) {
	// Initial configuration with default values
	dst := map[string]DBConfig{
		"mysql": {Host: "localhost", Port: 3306},
	}

	// New data (e.g., from environment variables) that only overrides Host
	src := map[string]any{
		"mysql": map[string]any{
			"Host": "127.0.0.1",
		},
	}

	// Perform conversion/merge
	cast.Convert(&dst, src)

	// Verify results
	mysql, ok := dst["mysql"]
	if !ok {
		t.Fatal("mysql config not found")
	}

	if mysql.Host != "127.0.0.1" {
		t.Errorf("Expected Host 127.0.0.1, got %s", mysql.Host)
	}

	if mysql.Port != 3306 {
		t.Errorf("Expected Port 3306, got %d", mysql.Port)
	}
}

func TestMapStructPointerMerge(t *testing.T) {
	// Initial configuration with default values (using pointers)
	dst := map[string]*DBConfig{
		"mysql": {Host: "localhost", Port: 3306},
	}

	// New data that only overrides Host
	src := map[string]any{
		"mysql": map[string]any{
			"Host": "127.0.0.1",
		},
	}

	// Perform conversion/merge
	cast.Convert(&dst, src)

	// Verify results
	mysql, ok := dst["mysql"]
	if !ok {
		t.Fatal("mysql config not found")
	}

	if mysql.Host != "127.0.0.1" {
		t.Errorf("Expected Host 127.0.0.1, got %s", mysql.Host)
	}

	if mysql.Port != 3306 {
		t.Errorf("Expected Port 3306, got %d", mysql.Port)
	}
}

func TestSliceToMapMerge(t *testing.T) {
	dst := map[string]int{
		"a": 1,
		"b": 2,
	}
	src := []any{"b", 20, "c", 30}

	cast.Convert(&dst, src)

	if dst["a"] != 1 {
		t.Errorf("Expected a=1, got %d", dst["a"])
	}
	if dst["b"] != 20 {
		t.Errorf("Expected b=20, got %d", dst["b"])
	}
	if dst["c"] != 30 {
		t.Errorf("Expected c=30, got %d", dst["c"])
	}
}

func TestStructToMapMerge(t *testing.T) {
	type Config struct {
		Host string
		Port int
	}
	dst := map[string]any{
		"host": "localhost",
		"port": 3306,
		"user": "root",
	}
	// Note: Struct fields are always "present", so Port:0 will overwrite port:3306
	src := Config{Host: "127.0.0.1", Port: 8080}

	cast.Convert(&dst, src)

	if dst["host"] != "127.0.0.1" {
		t.Errorf("Expected host 127.0.0.1, got %v", dst["host"])
	}
	if cast.Int(dst["port"]) != 8080 {
		t.Errorf("Expected port 8080, got %v", dst["port"])
	}
	if dst["user"] != "root" {
		t.Errorf("Expected user root, got %v", dst["user"])
	}
}