test(meshtimeout): e2e test that checks golden envoy configs (#12650)

## Motivation

When we test `BuildRules` we pass MeshTimeout policies as input and
check `outbound.ResourceRules` Go struct.

When we test MeshTimeout plugin we pass `outbound.ResourceRules` Go
struct as input and check envoy configs.

We need an easy way to pass MeshTimeout policies and check envoy
configs. It's sort of an integration test that involves 2 packages. The
easiest way to do that is to add another universal e2e test with golden
files. This way we have running Kuma CP and we basically test it as a
black box.

I managed to find 2 bugs using these tests:
* #12648
* #12649

## Implementation information

We check DPP `config` (marshalled Snapshot in Kuma CP) instead of the
actual Envoy config dump for a few reasons:
* no need to add logic that waits while config is propagated on DPP
* less setup-specific values we have to reduct to have stable golden
file (only IP addresses)
* we can use `kuma.io/effect: shadow` and quickly review the `diff`
policies introduces

---------

Signed-off-by: Ilya Lobkov <[email protected]>

pkg/test/ginkgo.go

@@ -62,10 +62,10 @@ func runSpecs(t *testing.T, description string) {
 
 // EntriesForFolder returns all files in the folder as gingko table entries for files *.input.yaml this makes it easier to add test by only adding input and golden files
 // if you prefix the file with a `F` we'll focus this specific test
-func EntriesForFolder(folder string) []ginkgo.TableEntry {
+func EntriesForFolder(folder string, pathPrefix ...string) []ginkgo.TableEntry {
 	ginkgo.GinkgoHelper()
 	var entries []ginkgo.TableEntry
-	testDir := path.Join("testdata", folder)
+	testDir := path.Join(append(pathPrefix, "testdata", folder)...)
 	files, err := os.ReadDir(testDir)
 	if err != nil {
 		panic(err)

test/e2e_env/universal/envoyconfig/envoyconfig.go

@@ -0,0 +1,101 @@
+package envoyconfig
+
+import (
+	"encoding/json"
+	"os"
+	"regexp"
+	"strings"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+
+	mesh_proto "github.com/kumahq/kuma/api/mesh/v1alpha1"
+	"github.com/kumahq/kuma/pkg/test"
+	"github.com/kumahq/kuma/pkg/test/matchers"
+	"github.com/kumahq/kuma/pkg/test/resources/builders"
+	. "github.com/kumahq/kuma/test/framework"
+	"github.com/kumahq/kuma/test/framework/client"
+	"github.com/kumahq/kuma/test/framework/envs/universal"
+)
+
+func EnvoyConfigTest() {
+	meshName := "envoyconfig"
+
+	BeforeAll(func() {
+		err := NewClusterSetup().
+			Install(
+				Yaml(
+					builders.Mesh().
+						WithName(meshName).
+						WithoutInitialPolicies().
+						WithMeshServicesEnabled(mesh_proto.Mesh_MeshServices_Exclusive),
+				),
+			).
+			Install(DemoClientUniversal("demo-client", meshName,
+				WithTransparentProxy(true)),
+			).
+			Install(TestServerUniversal("test-server", meshName,
+				WithArgs([]string{"echo", "--instance", "universal-1"})),
+			).
+			Setup(universal.Cluster)
+		Expect(err).ToNot(HaveOccurred())
+
+		Eventually(func(g Gomega) {
+			_, err := client.CollectEchoResponse(universal.Cluster, "demo-client", "test-server.svc.mesh.local")
+			g.Expect(err).ToNot(HaveOccurred())
+		}).Should(Succeed())
+	})
+
+	AfterEachFailure(func() {
+		DebugUniversal(universal.Cluster, meshName)
+	})
+
+	E2EAfterAll(func() {
+		Expect(universal.Cluster.DeleteMeshApps(meshName)).To(Succeed())
+		Expect(universal.Cluster.DeleteMesh(meshName)).To(Succeed())
+	})
+
+	E2EAfterEach(func() {
+		// delete all meshtimeout policies
+		out, err := universal.Cluster.GetKumactlOptions().RunKumactlAndGetOutput("get", "meshtimeouts", "--mesh", meshName, "-o", "json")
+		Expect(err).ToNot(HaveOccurred())
+		var output struct {
+			Items []struct {
+				Name string `json:"name"`
+			} `json:"items"`
+		}
+		Expect(json.Unmarshal([]byte(out), &output)).To(Succeed())
+		for _, item := range output.Items {
+			Expect(universal.Cluster.GetKumactlOptions().RunKumactl("delete", "meshtimeout", item.Name, "--mesh", meshName)).To(Succeed())
+		}
+	})
+
+	redactIPs := func(jsonStr string) string {
+		ipRegex := regexp.MustCompile(`\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b`)
+		return ipRegex.ReplaceAllString(jsonStr, "IP_REDACTED")
+	}
+
+	getConfig := func(dpp string) string {
+		output, err := universal.Cluster.GetKumactlOptions().
+			RunKumactlAndGetOutput("inspect", "dataplane", dpp, "--type", "config", "--mesh", meshName, "--shadow", "--include=diff")
+		Expect(err).ToNot(HaveOccurred())
+		return redactIPs(output)
+	}
+
+	DescribeTable("should generate proper Envoy config",
+		func(inputFile string) {
+			// given
+			input, err := os.ReadFile(inputFile)
+			Expect(err).ToNot(HaveOccurred())
+
+			// when
+			if len(input) > 0 {
+				Expect(universal.Cluster.Install(YamlUniversal(string(input)))).To(Succeed())
+			}
+
+			// then
+			Expect(getConfig("demo-client")).To(matchers.MatchGoldenJSON(strings.Replace(inputFile, "input.yaml", "demo-client.golden.json", 1)))
+			Expect(getConfig("test-server")).To(matchers.MatchGoldenJSON(strings.Replace(inputFile, "input.yaml", "test-server.golden.json", 1)))
+		}, test.EntriesForFolder("meshtimeout", "envoyconfig"),
+	)
+}