Feature flag assertion validations

cmd/ytt/ytt.go

@@ -29,7 +29,8 @@ func main() {
 }
 
 func enableExperimentalFeatures() {
-	if experiments, isSet := os.LookupEnv("YTTEXPERIMENTS"); isSet {
+	if experiments, isSet := os.LookupEnv("YTTEXPERIMENTS"); isSet && experiments != "" {
+		// if we didn't ignore empty string, we'd attempt to Enable(""); that would panic (rather than ignore).
 		for _, experiment := range strings.Split(experiments, ",") {
 			feature.Flags().Enable(experiment)
 			fmt.Fprintf(os.Stderr, "Experimental feature %q enabled.\n", experiment)

pkg/assertions/assert.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 
 	"github.com/k14s/starlark-go/starlark"
+	"github.com/vmware-tanzu/carvel-ytt/pkg/feature"
 	"github.com/vmware-tanzu/carvel-ytt/pkg/template"
 	"github.com/vmware-tanzu/carvel-ytt/pkg/yamlmeta"
 )
@@ -23,9 +24,13 @@ const (
 // When a Node's value is invalid, the errors are collected and returned in an AssertCheck.
 // Otherwise, returns empty AssertCheck and nil error.
 func ProcessAndRunValidations(n yamlmeta.Node, threadName string) (AssertCheck, error) {
+	if !feature.Flags().IsEnabled(feature.Validations) {
+		return AssertCheck{}, nil
+	}
 	if n == nil {
 		return AssertCheck{}, nil
 	}
+
 	err := yamlmeta.Walk(n, &convertAssertAnnsToValidations{})
 	if err != nil {
 		return AssertCheck{}, err

pkg/cmd/template/cmd_test.go

@@ -4,15 +4,28 @@
 package template_test
 
 import (
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	cmdtpl "github.com/vmware-tanzu/carvel-ytt/pkg/cmd/template"
 	"github.com/vmware-tanzu/carvel-ytt/pkg/cmd/ui"
+	"github.com/vmware-tanzu/carvel-ytt/pkg/feature"
 	"github.com/vmware-tanzu/carvel-ytt/pkg/files"
 )
 
+// TestMain is invoked when any tests are run in this package, *instead of* those tests being run directly.
+// This allows for setup to occur before *any* test is run.
+func TestMain(m *testing.M) {
+	// Enable experimental code
+	feature.Flags().Enable(feature.Validations)
+
+	exitVal := m.Run() // execute the specified tests
+
+	os.Exit(exitVal) // required in order to properly report the error level when tests fail.
+}
+
 func TestLoad(t *testing.T) {
 	yamlTplData := []byte(`
 #@ load("@ytt:data", "data")

pkg/feature/flags.go

@@ -24,11 +24,12 @@ import "fmt"
 
 // Names of features that can be toggled
 const (
-	Noop = "noop"
+	Noop        = "noop"
+	Validations = "validations"
 )
 
 // allFeatures is the total list of features. It must contain all the constants defined, above.
-var allFeatures = []string{Noop}
+var allFeatures = []string{Noop, Validations}
 
 // Flags returns the singleton instance of feature flags.
 func Flags() *Flagset {