Add EqualLabelSelectors utility function

This patch introduces EqualLabelSelectors function that allows to
match two labelSelectors. This is useful when comparing Secrets
or other k8s resources that a service operator watches.

Signed-off-by: Francesco Pantano <fpantano@redhat.com>

Author: fmount

modules/common/labels/labels.go

@@ -19,6 +19,7 @@ package labels
 import (
 	"github.com/openstack-k8s-operators/lib-common/modules/common"
 	"github.com/openstack-k8s-operators/lib-common/modules/common/util"
+	"k8s.io/apimachinery/pkg/api/equality"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
@@ -108,3 +109,10 @@ func GetLabelSelector(
 		MatchLabels: serviceLabels,
 	}
 }
+
+// EqualLabelSelectors - returns true if two labelSelectors matches, false
+// otherwise
+func EqualLabelSelectors(
+	l1, l2 metav1.LabelSelector) bool {
+	return equality.Semantic.DeepEqual(l1, l2)
+}

modules/common/labels/labels_test.go

@@ -124,3 +124,20 @@ func TestGetLabels(t *testing.T) {
 		})
 	}
 }
+
+// Given a map[string]string, get the corresponding labelSelectors and compare
+// them via the EqualLabelSelectors utility
+func TestEqualLabelSelectors(t *testing.T) {
+	t.Run("Compare labelSelectors", func(t *testing.T) {
+		g := NewWithT(t)
+
+		l0 := GetLabelSelector(map[string]string{})
+		l1 := GetLabelSelector(map[string]string{"app": "foo", "version": "v1", "property": "bar"})
+		l2 := l1
+		l3 := GetLabelSelector(map[string]string{"app": "api", "version": "v1"})
+
+		g.Expect(EqualLabelSelectors(l1, l0)).To(BeFalse())
+		g.Expect(EqualLabelSelectors(l1, l2)).To(BeTrue())
+		g.Expect(EqualLabelSelectors(l1, l3)).To(BeFalse())
+	})
+}