test: Ensure defaults from JSON schema are respected

Without this, defaults declared in the JSON schema are not included in validation
steps, which can lead to invalid failures, while also not allowing for tests that
target defaults.

Author: jimmidyson

common/go.mod

@@ -63,6 +63,7 @@ require (
 	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
 	golang.org/x/net v0.19.0 // indirect
 	golang.org/x/oauth2 v0.14.0 // indirect
+	golang.org/x/sync v0.5.0 // indirect
 	golang.org/x/sys v0.16.0 // indirect
 	golang.org/x/term v0.15.0 // indirect
 	golang.org/x/text v0.14.0 // indirect

common/pkg/testutils/openapi/convert.go

@@ -14,7 +14,7 @@ import (
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
 )
 
-// convertToAPIExtensionsJSONSchemaProps converts a clusterv1.JSONSchemaProps to apiextensions.JSONSchemaProp.
+// ConvertToAPIExtensionsJSONSchemaProps converts a clusterv1.JSONSchemaProps to apiextensions.JSONSchemaProp.
 // NOTE: This is used whenever we want to use one of the upstream libraries, as they use apiextensions.JSONSchemaProp.
 // NOTE: If new fields are added to clusterv1.JSONSchemaProps (e.g. to support complex types), the corresponding
 // schema validation must be added to validateRootSchema too.

common/pkg/testutils/openapi/validate.go

@@ -10,6 +10,7 @@ import (
 
 	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
 	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema/defaulting"
 	structuralpruning "k8s.io/apiextensions-apiserver/pkg/apiserver/schema/pruning"
 	"k8s.io/apiextensions-apiserver/pkg/apiserver/validation"
 	"k8s.io/apimachinery/pkg/util/validation/field"
@@ -62,6 +63,18 @@ func ValidateClusterVariable(
 		)}
 	}
 
+	s, err := structuralschema.NewStructural(apiExtensionsSchema)
+	if err != nil {
+		return field.ErrorList{field.InternalError(fldPath,
+			fmt.Errorf(
+				"failed to create structural schema for variable %q; ClusterClass should be checked: %v",
+				value.Name,
+				err,
+			),
+		)}
+	}
+	defaulting.Default(variableValue, s)
+
 	// Validate variable against the schema.
 	// NOTE: We're reusing a library func used in CRD validation.
 	if err := validation.ValidateCustomResource(fldPath, variableValue, validator); err != nil {