fix: Caddy config regeneration due to non-deterministic container serialisation (fixes #111)

internal/machine/caddyconfig/controller_test.go

@@ -0,0 +1,64 @@
+package caddyconfig
+
+import (
+	"net/netip"
+	"reflect"
+	"testing"
+
+	"github.com/psviderski/uncloud/pkg/api"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestContainerFingerprint_EqualCoversAllFields is a guard: when a field is added to containerFingerprint,
+// Equal must also compare it. A mutation of any single field should flip equality to false. If this test fails
+// after adding a field, update Equal to include it.
+func TestContainerFingerprint_EqualCoversAllFields(t *testing.T) {
+	t.Parallel()
+
+	base := containerFingerprint{
+		ID: "container-1",
+		IP: netip.MustParseAddr("10.210.0.2"),
+		Ports: []api.PortSpec{{
+			Hostname:      "app.example.com",
+			ContainerPort: 8080,
+			Protocol:      api.ProtocolHTTP,
+			Mode:          api.PortModeIngress,
+		}},
+		CaddyConfig: "caddy-config",
+	}
+
+	assert.True(t, base.Equal(base), "base fingerprint must be equal to itself")
+
+	rt := reflect.TypeOf(base)
+	for i := 0; i < rt.NumField(); i++ {
+		field := rt.Field(i)
+		t.Run(field.Name, func(t *testing.T) {
+			t.Parallel()
+
+			mutated := base
+			mutated.Ports = append([]api.PortSpec(nil), base.Ports...)
+			v := reflect.ValueOf(&mutated).Elem().FieldByName(field.Name)
+
+			switch field.Name {
+			case "ID", "CaddyConfig":
+				v.SetString(v.String() + "-changed")
+			case "IP":
+				v.Set(reflect.ValueOf(netip.MustParseAddr("10.210.0.99")))
+			case "Ports":
+				mutated.Ports = []api.PortSpec{{
+					Hostname:      "different.example.com",
+					ContainerPort: 9090,
+					Protocol:      api.ProtocolHTTP,
+					Mode:          api.PortModeIngress,
+				}}
+			default:
+				t.Fatalf("containerFingerprint has a new field %q without a mutation case in this test. "+
+					"Add a case here and make sure Equal() compares it.", field.Name)
+			}
+
+			assert.False(t, base.Equal(mutated),
+				"changing %q must flip Equal to false. Update containerFingerprint.Equal to compare it.",
+				field.Name)
+		})
+	}
+}