feat: unify generated configuration loading and extensible decoders

examples/configuration/main_test.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+)
+
+func TestExamples(t *testing.T) {
+	var previous Config
+	for i, ext := range []string{"json", "yaml", "xml", "custom"} {
+		source := ext
+		if source == "custom" {
+			source = "json"
+		}
+		data, err := examples.ReadFile("config." + source)
+		if err != nil {
+			t.Fatal(err)
+		}
+		path := filepath.Join(t.TempDir(), "app."+ext)
+		if err = os.WriteFile(path, data, 0600); err != nil {
+			t.Fatal(err)
+		}
+		got, err := load(path)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if i > 0 && !reflect.DeepEqual(previous, got) {
+			t.Fatal("format difference")
+		}
+		previous = got
+	}
+}