// limitations under the License.

package features

import (
	"time"

	"istio.io/istio/pkg/env"
	"istio.io/istio/pkg/log"
)

// Define telemetry related features here.
var (
	traceSamplingVar = env.Register(
		"PILOT_TRACE_SAMPLING",
		1.0,
		"Sets the mesh-wide trace sampling percentage. Should be 0.0 - 100.0. Precision to 0.01. "+
			"Default is 1.0.",
	)

	generators[v3.EndpointType] = edsGen
	ecdsGen := &xds.EcdsGenerator{ConfigGenerator: cg}
	if env.CredentialsController != nil {
		generators[v3.SecretType] = xds.NewSecretGen(env.CredentialsController, s.Cache, clusterID, env.Mesh())
		ecdsGen.SetCredController(env.CredentialsController)
	}
	generators[v3.ExtensionConfigurationType] = ecdsGen

			Type:   errType,
			Detail: errorString,
		}
	}

	env, err := c.varEnvs[envVarName].Env(environment.StoredExpressions)
	if err != nil {
		return resultError(fmt.Sprintf("unexpected error loading CEL environment: %v", err), apiservercel.ErrorTypeInternal)
	}

	ast, issues := env.Compile(expressionAccessor.GetExpression())
	if issues != nil {

			"If unset fallbacks to ETCD_CREDS env.")
}

func lookupEnv(env string) (string, error) {
	result, ok := os.LookupEnv(env)
	if !ok || len(result) == 0 {
		return result, fmt.Errorf("%s variable unset - expected failure", env)
	}
	return result, nil
}

func fallbackToEnv(flag, env string) (string, error) {
	klog.Infof("--%s unset - falling back to %s variable", flag, env)
	return lookupEnv(env)
}

  const absl::Status write_status =
      WriteStringToFile(dst_file_path, "test_string");
  ASSERT_THAT(write_status, IsOk());

  auto* const env = tsl::Env::Default();
  ASSERT_THAT(env->FileExists(dst_file_path), IsOk());

  std::string data{};
  ASSERT_THAT(tsl::ReadFileToString(env, dst_file_path, &data), IsOk());

  EXPECT_THAT(data, Eq("test_string"));
}

TEST(IoTest, ReadFileToString) {

import (
	"runtime"
	"time"

	"istio.io/istio/pkg/env"
)

// Define performance tuning related features here.
var (
	MaxConcurrentStreams = env.Register(
		"ISTIO_GPRC_MAXSTREAMS",
		100000,
		"Sets the maximum number of concurrent grpc streams.",
	).Get()

	// MaxRecvMsgSize The max receive buffer size of gRPC received channel of Pilot in bytes.
	MaxRecvMsgSize = env.Register(
		"ISTIO_GPRC_MAXRECVMSGSIZE",
		4*1024*1024,

env TESTGO_VERSION=go1.500
env TESTGO_VERSION_SWITCH=mismatch

# go env GOMOD should not trigger a toolchain download
cd $GOPATH/mod
go env GOMOD
stdout mod[/\\]go.mod
! stderr 'go: toolchain go1.500 invoked to provide go1.700'

# go env GOWORK should not trigger a toolchain download
cd $GOPATH/work
go env GOWORK
stdout work[/\\]go.work
! stderr 'go: toolchain go1.500 invoked to provide go1.700'

-- $GOPATH/mod/go.mod --

// limitations under the License.

package features

import (
	"istio.io/istio/pkg/env"
)

// Define flags that affect XDS config generation here.
var (
	// EnableMysqlFilter enables injection of `envoy.filters.network.mysql_proxy` in the filter chain.
	// Pilot injects this outbound filter if the service port name is `mysql`.
	EnableMysqlFilter = env.Register(
		"PILOT_ENABLE_MYSQL_FILTER",
		false,

func mustCreateEnv(t testing.TB, envOptions ...cel.EnvOption) *cel.Env {
	envSet, err := environment.MustBaseEnvSet(environment.DefaultCompatibilityVersion(), true).
		Extend(environment.VersionedOptions{
			IntroducedVersion: version.MajorMinor(1, 30),
			EnvOptions:        envOptions,
		})
	if err != nil {
		t.Fatalf("fail to create env set: %v", err)
	}
	env, err := envSet.Env(environment.StoredExpressions)
	if err != nil {

# Instead, we build a fresh copy of the binary with known settings.
go build -o $WORK/new/bin/go$GOEXE cmd/go &
go build -trimpath -o $WORK/bin/check$GOEXE check.go &
wait

env TESTGOROOT=$GOROOT
env GOROOT=

# Relocated Executable
exec $WORK/bin/check$GOEXE $WORK/new/bin/go$GOEXE $TESTGOROOT

# Relocated Tree:
# If the binary is sitting in a bin dir next to ../pkg/tool, that counts as a GOROOT,