Make product API versions independently installable

backend/product/app/server/internal/config_test.go

@@ -5,6 +5,7 @@ import (
 	"git.sendico.io/tech/sxchnge/product/app/api"
 	"git.sendico.io/tech/sxchnge/shared/errors"
 	"os"
+	"strings"
 	"testing"
 )
 
@@ -32,3 +33,34 @@ func TestExampleConfigMatchesCopiedRuntime(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestVersionSelectionPreservesOmittedAndEmptyLists(t *testing.T) {
+	data, err := os.ReadFile("../../../config.example.yml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, tc := range []struct {
+		name, setting string
+		wantNil       bool
+		wantLength    int
+	}{
+		{name: "omitted", wantNil: true},
+		{name: "disabled", setting: "  versions: []\n"},
+		{name: "explicit", setting: "  versions: [{version: v1, path: /gateway/v1}]\n", wantLength: 1},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			instance := &Imp{runtime: api.RuntimeConfig{}}
+			configured := strings.Replace(string(data), "api:\n", "api:\n"+tc.setting, 1)
+			if err := instance.decodeConfig([]byte(configured)); err != nil {
+				t.Fatal(err)
+			}
+			versions := instance.config.API.SharedConfig().Versions
+			if (versions == nil) != tc.wantNil || len(versions) != tc.wantLength {
+				t.Fatalf("unexpected versions: %#v", versions)
+			}
+			if tc.wantLength == 1 && (versions[0].Version != "v1" || versions[0].Path != "/gateway/v1") {
+				t.Fatalf("lost version configuration: %#v", versions)
+			}
+		})
+	}
+}