Cover containsCIDR with unit tests

To make sure that it works as expected.

subnet/kube/kube_test.go

@@ -0,0 +1,52 @@
+// Copyright 2018 flannel authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kube
+
+import (
+	"net"
+
+	"testing"
+)
+
+func TestContainsCIDR(t *testing.T) {
+	testCases := []struct {
+		cidr1          string
+		cidr2          string
+		expectedResult bool
+	}{
+		{"10.244.0.0/16", "10.244.0.0/16", true},
+		{"10.244.0.0/16", "10.244.0.0/24", true},
+		{"10.244.0.0/16", "10.244.255.0/24", true},
+		{"10.244.0.0/16", "10.244.0.0/15", false},
+		{"10.244.0.0/16", "192.168.0.0/24", false},
+
+		{"2001:0db8:1234::/48", "2001:0db8:1234::/48", true},
+		{"2001:0db8:1234::/48", "2001:0db8:1234::/64", true},
+		{"2001:0db8:1234::/48", "2001:0db8:1234:ffff::/64", true},
+		{"2001:0db8:1234::/48", "2001:0db8:1234::/47", false},
+		{"2001:0db8:1234::/48", "fe02::/32", false},
+	}
+
+	for i, tc := range testCases {
+		_, ipnet1, _ := net.ParseCIDR(tc.cidr1)
+		_, ipnet2, _ := net.ParseCIDR(tc.cidr2)
+
+		actualResult := containsCIDR(ipnet1, ipnet2)
+
+		if actualResult != tc.expectedResult {
+			t.Errorf("#%d: Expected %t, but was %t.", i, tc.expectedResult, actualResult)
+		}
+	}
+}