Add public facade value wrappers

internal/facade/facade_external_test.go

@@ -0,0 +1,43 @@
+package configkit_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"testing"
+
+	configkit "gitea.maximumdirect.net/eric/ConfigKit/internal/facade"
+)
+
+var (
+	_ error          = (*configkit.LoadError)(nil)
+	_ fmt.Formatter  = configkit.Secret{}
+	_ fmt.Stringer   = configkit.Path{}
+	_ json.Marshaler = configkit.Secret{}
+)
+
+func TestFacadeValuesRemainRootOwned(t *testing.T) {
+	t.Parallel()
+	const packagePath = "gitea.maximumdirect.net/eric/ConfigKit/internal/facade"
+	for _, candidate := range []reflect.Type{
+		reflect.TypeFor[configkit.Path](), reflect.TypeFor[configkit.Source](),
+		reflect.TypeFor[configkit.Secret](), reflect.TypeFor[configkit.Diagnostic](),
+		reflect.TypeFor[configkit.LoadError](),
+	} {
+		if candidate.PkgPath() != packagePath {
+			t.Fatalf("type %s belongs to %q", candidate, candidate.PkgPath())
+		}
+	}
+	secret := configkit.SecretEnv("SAFE_NAME")
+	formatted := fmt.Sprintf("%#v", secret)
+	encoded, err := json.Marshal(secret)
+	if formatted == "" || err != nil || string(encoded) != `"SAFE_NAME"` {
+		t.Fatalf("secret rendering = %q, %s, %v", formatted, encoded, err)
+	}
+	if got := configkit.Keys("a/b~").Index(0).String(); got != "/a~1b~0/0" {
+		t.Fatalf("path = %q", got)
+	}
+	if got := (&configkit.LoadError{}).Error(); got != "configkit: configuration load failed" {
+		t.Fatalf("zero LoadError = %q", got)
+	}
+}