test(gateway): add tests for toProtoCircuitBreaker and ApplyPartialSnapshotWithSecrets

- Test nil input, valid config, and zero value for CB proto conversion
- Test nil current snapshot, backend replacement, and field preservation
- Covers recent optimizer changes in xds and translator packages

Author: mahmut-Abi

internal/translator/partial_test.go

@@ -0,0 +1,51 @@
+package translator
+
+import (
+	"testing"
+
+	"github.com/nantian-gw/gateway/internal/ir"
+)
+
+func TestApplyPartialSnapshotWithSecrets_NilCurrent(t *testing.T) {
+	backends := []ir.BackendCluster{{Name: "svc1", Namespace: "ns1"}}
+	listeners := []ir.Listener{{Name: "l1"}}
+	secrets := []ir.SecretMaterial{{Name: "s1", Namespace: "ns1"}}
+
+	result := ApplyPartialSnapshotWithSecrets(nil, backends, listeners, secrets)
+	if result == nil {
+		t.Fatal("expected non-nil result")
+	}
+	if len(result.Backends) != 1 || result.Backends[0].Name != "svc1" {
+		t.Error("backends not set correctly")
+	}
+	if len(result.Listeners) != 1 || result.Listeners[0].Name != "l1" {
+		t.Error("listeners not set correctly")
+	}
+	if len(result.Secrets) != 1 || result.Secrets[0].Name != "s1" {
+		t.Error("secrets not set correctly")
+	}
+}
+
+func TestApplyPartialSnapshotWithSecrets_ReplaceBackends(t *testing.T) {
+	current := &ir.Snapshot{
+		ID:         "v1",
+		Backends:   []ir.BackendCluster{{Name: "old-svc", Namespace: "ns1"}},
+		Listeners:  []ir.Listener{{Name: "l1", Port: 80}},
+		HTTPRoutes: []ir.HTTPRoute{{Name: "r1", Namespace: "ns1"}},
+	}
+	newBackends := []ir.BackendCluster{{Name: "new-svc", Namespace: "ns1"}}
+
+	result := ApplyPartialSnapshotWithSecrets(current, newBackends, nil, nil)
+	if result.ID != "v1" {
+		t.Errorf("ID = %s, want v1", result.ID)
+	}
+	if len(result.Backends) != 1 || result.Backends[0].Name != "new-svc" {
+		t.Error("backends not replaced")
+	}
+	if len(result.Listeners) != 1 || result.Listeners[0].Port != 80 {
+		t.Error("listeners not preserved")
+	}
+	if len(result.HTTPRoutes) != 1 || result.HTTPRoutes[0].Name != "r1" {
+		t.Error("routes not preserved")
+	}
+}

internal/xds/snapshot_proto_test.go

@@ -0,0 +1,38 @@
+package xds
+
+import (
+	"testing"
+
+	"github.com/nantian-gw/gateway/internal/ir"
+	controlv1 "github.com/nantian-gw/proto/gateway/control/v1"
+)
+
+func TestToProtoCircuitBreaker(t *testing.T) {
+	// nil input returns nil
+	if got := toProtoCircuitBreaker(nil); got != nil {
+		t.Errorf("toProtoCircuitBreaker(nil) = %v, want nil", got)
+	}
+
+	// valid input
+	input := &ir.CircuitBreakerConfig{MaxInflightRequests: 100}
+	got := toProtoCircuitBreaker(input)
+	if got == nil {
+		t.Fatal("expected non-nil result")
+	}
+	if got.MaxInflightRequests != 100 {
+		t.Errorf("MaxInflightRequests = %d, want 100", got.MaxInflightRequests)
+	}
+	if _, ok := any(got).(*controlv1.CircuitBreakerConfig); !ok {
+		t.Errorf("expected *controlv1.CircuitBreakerConfig, got %T", got)
+	}
+
+	// zero value
+	input2 := &ir.CircuitBreakerConfig{MaxInflightRequests: 0}
+	got2 := toProtoCircuitBreaker(input2)
+	if got2 == nil {
+		t.Fatal("expected non-nil result for zero value")
+	}
+	if got2.MaxInflightRequests != 0 {
+		t.Errorf("MaxInflightRequests = %d, want 0", got2.MaxInflightRequests)
+	}
+}