Add cel tests for upstreamsettingspolicy (#3742)

Problem: There were no CEL tests for UpstreamSettingsPolicy

Solution: I added it

Author: sarthyparty

tests/cel/common.go

@@ -22,12 +22,15 @@ const (
 	grpcRouteKind = "GRPCRoute"
 	tcpRouteKind  = "TCPRoute"
 	invalidKind   = "InvalidKind"
+	serviceKind   = "Service"
 )
 
 const (
 	gatewayGroup   = "gateway.networking.k8s.io"
 	invalidGroup   = "invalid.networking.k8s.io"
 	discoveryGroup = "discovery.k8s.io/v1"
+	coreGroup      = "core"
+	emptyGroup     = ""
 )
 
 // ClientSettingsPolicy validation errors.
@@ -44,6 +47,13 @@ const (
 	expectedMinReplicasLessThanOrEqualError = `minReplicas must be less than or equal to maxReplicas`
 )
 
+// UpstreamSettingsPolicy validation errors.
+const (
+	expectedTargetRefKindServiceError = `TargetRefs Kind must be: Service`
+	expectedTargetRefGroupCoreError   = `TargetRefs Group must be core`
+	expectedTargetRefNameUniqueError  = `TargetRef Name must be unique`
+)
+
 const (
 	defaultNamespace = "default"
 )