Added func ZonesToSet

An admin shall be able to configure a comma separated list of zones for a StorageClass.

That's why the func ZonesToSet (string) (set.String, error) is added. The func ZonesToSet converts a string containing a comma separated list of zones to a set. In case the list contains an empty zone an error is returned.

pkg/volume/util.go

@@ -410,3 +410,17 @@ func JoinMountOptions(userOptions []string, systemOptions []string) []string {
 	}
 	return allMountOptions.UnsortedList()
 }
+
+// ZonesToSet converts a string containing a comma separated list of zones to set
+func ZonesToSet(zonesString string) (sets.String, error) {
+	zonesSlice := strings.Split(zonesString, ",")
+	zonesSet := make(sets.String)
+	for _, zone := range zonesSlice {
+		trimmedZone := strings.TrimSpace(zone)
+		if trimmedZone == "" {
+			return make(sets.String), fmt.Errorf("comma separated list of zones (%q) must not contain an empty zone", zonesString)
+		}
+		zonesSet.Insert(trimmedZone)
+	}
+	return zonesSet, nil
+}

pkg/volume/util_test.go

@@ -523,3 +523,37 @@ func TestChooseZoneForVolume(t *testing.T) {
 		}
 	}
 }
+
+func TestZonesToSet(t *testing.T) {
+	functionUnderTest := "ZonesToSet"
+	// First part: want an error
+	sliceOfZones := []string{"", ",", "us-east-1a, , us-east-1d", ", us-west-1b", "us-west-2b,"}
+	for _, zones := range sliceOfZones {
+		if got, err := ZonesToSet(zones); err == nil {
+			t.Errorf("%v(%v) returned (%v), want (%v)", functionUnderTest, zones, got, "an error")
+		}
+	}
+
+	// Second part: want no error
+	tests := []struct {
+		zones string
+		want  sets.String
+	}{
+		{
+			zones: "us-east-1a",
+			want:  sets.String{"us-east-1a": sets.Empty{}},
+		},
+		{
+			zones: "us-east-1a, us-west-2a",
+			want: sets.String{
+				"us-east-1a": sets.Empty{},
+				"us-west-2a": sets.Empty{},
+			},
+		},
+	}
+	for _, tt := range tests {
+		if got, err := ZonesToSet(tt.zones); err != nil || !got.Equal(tt.want) {
+			t.Errorf("%v(%v) returned (%v), want (%v)", functionUnderTest, tt.zones, got, tt.want)
+		}
+	}
+}