Add the GCP provider: four-call surface, fire-and-forget ops, zone-qualified IDs

Co-Authored-By: Claude <noreply@anthropic.com>

internal/provider/gcp/errors_test.go

@@ -0,0 +1,71 @@
+package gcp
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+
+	"google.golang.org/api/googleapi"
+
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
+)
+
+func gerr(code int, reasons ...string) error {
+	e := &googleapi.Error{Code: code, Message: "boom"}
+	for _, r := range reasons {
+		e.Errors = append(e.Errors, googleapi.ErrorItem{Reason: r})
+	}
+	return e
+}
+
+func TestClassify(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		err  error
+		want error
+	}{
+		{name: "404 is NotFound", err: gerr(404), want: provider.ErrNotFound},
+		{name: "429 is Quota", err: gerr(429), want: provider.ErrQuotaExceeded},
+		{name: "403 quotaExceeded is Quota", err: gerr(403, "quotaExceeded"), want: provider.ErrQuotaExceeded},
+		{name: "403 rateLimitExceeded is Quota", err: gerr(403, "rateLimitExceeded"), want: provider.ErrQuotaExceeded},
+		{name: "403 plain is Permanent", err: gerr(403, "forbidden"), want: provider.ErrPermanent},
+		{name: "400 is Permanent", err: gerr(400), want: provider.ErrPermanent},
+		{name: "401 is Permanent", err: gerr(401), want: provider.ErrPermanent},
+		{name: "408 is Transient", err: gerr(408), want: provider.ErrTransient},
+		{name: "500 is Transient", err: gerr(500), want: provider.ErrTransient},
+		{name: "503 is Transient", err: gerr(503), want: provider.ErrTransient},
+		{name: "409 is Transient (alreadyExists is handled before classify)", err: gerr(409), want: provider.ErrTransient},
+		{name: "plain network error is Transient", err: errors.New("connection reset"), want: provider.ErrTransient},
+		{name: "wrapped googleapi error still classifies", err: fmt.Errorf("calling api: %w", gerr(404)), want: provider.ErrNotFound},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if got := classify(tc.err); got != tc.want {
+				t.Errorf("classify() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
+// The wrapped error must satisfy both halves of the taxonomy contract:
+// errors.Is against the sentinel AND errors.As back to the SDK error.
+func TestWrapErr_isAndAsBothWork(t *testing.T) {
+	t.Parallel()
+	p := &Provider{name: "gcp-eu"}
+	wrapped := p.wrapErr("get", "zones/z/instances/i", gerr(404))
+
+	if !errors.Is(wrapped, provider.ErrNotFound) {
+		t.Error("errors.Is(wrapped, ErrNotFound) = false")
+	}
+	var ge *googleapi.Error
+	if !errors.As(wrapped, &ge) || ge.Code != 404 {
+		t.Error("errors.As back to *googleapi.Error failed")
+	}
+	if provider.Class(wrapped) != provider.ErrNotFound {
+		t.Errorf("Class() = %v, want ErrNotFound", provider.Class(wrapped))
+	}
+}