snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/xds/testutils/balancer_test.go

@@ -0,0 +1,147 @@
+/*
+ *
+ * Copyright 2020 gRPC 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 testutils
+
+import (
+	"testing"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/internal/testutils"
+)
+
+func TestIsRoundRobin(t *testing.T) {
+	var (
+		sc1 = &testutils.TestSubConn{}
+		sc2 = &testutils.TestSubConn{}
+		sc3 = &testutils.TestSubConn{}
+	)
+
+	testCases := []struct {
+		desc string
+		want []balancer.SubConn
+		got  []balancer.SubConn
+		pass bool
+	}{
+		{
+			desc: "0 element",
+			want: []balancer.SubConn{},
+			got:  []balancer.SubConn{},
+			pass: true,
+		},
+		{
+			desc: "1 element RR",
+			want: []balancer.SubConn{sc1},
+			got:  []balancer.SubConn{sc1, sc1, sc1, sc1},
+			pass: true,
+		},
+		{
+			desc: "1 element not RR",
+			want: []balancer.SubConn{sc1},
+			got:  []balancer.SubConn{sc1, sc2, sc1},
+			pass: false,
+		},
+		{
+			desc: "2 elements RR",
+			want: []balancer.SubConn{sc1, sc2},
+			got:  []balancer.SubConn{sc1, sc2, sc1, sc2, sc1, sc2},
+			pass: true,
+		},
+		{
+			desc: "2 elements RR different order from want",
+			want: []balancer.SubConn{sc2, sc1},
+			got:  []balancer.SubConn{sc1, sc2, sc1, sc2, sc1, sc2},
+			pass: true,
+		},
+		{
+			desc: "2 elements RR not RR, mistake in first iter",
+			want: []balancer.SubConn{sc1, sc2},
+			got:  []balancer.SubConn{sc1, sc1, sc1, sc2, sc1, sc2},
+			pass: false,
+		},
+		{
+			desc: "2 elements RR not RR, mistake in second iter",
+			want: []balancer.SubConn{sc1, sc2},
+			got:  []balancer.SubConn{sc1, sc2, sc1, sc1, sc1, sc2},
+			pass: false,
+		},
+		{
+			desc: "2 elements weighted RR",
+			want: []balancer.SubConn{sc1, sc1, sc2},
+			got:  []balancer.SubConn{sc1, sc1, sc2, sc1, sc1, sc2},
+			pass: true,
+		},
+		{
+			desc: "2 elements weighted RR different order",
+			want: []balancer.SubConn{sc1, sc1, sc2},
+			got:  []balancer.SubConn{sc1, sc2, sc1, sc1, sc2, sc1},
+			pass: true,
+		},
+
+		{
+			desc: "3 elements RR",
+			want: []balancer.SubConn{sc1, sc2, sc3},
+			got:  []balancer.SubConn{sc1, sc2, sc3, sc1, sc2, sc3, sc1, sc2, sc3},
+			pass: true,
+		},
+		{
+			desc: "3 elements RR different order",
+			want: []balancer.SubConn{sc1, sc2, sc3},
+			got:  []balancer.SubConn{sc3, sc2, sc1, sc3, sc2, sc1},
+			pass: true,
+		},
+		{
+			desc: "3 elements weighted RR",
+			want: []balancer.SubConn{sc1, sc1, sc1, sc2, sc2, sc3},
+			got:  []balancer.SubConn{sc1, sc2, sc3, sc1, sc2, sc1, sc1, sc2, sc3, sc1, sc2, sc1},
+			pass: true,
+		},
+		{
+			desc: "3 elements weighted RR not RR, mistake in first iter",
+			want: []balancer.SubConn{sc1, sc1, sc1, sc2, sc2, sc3},
+			got:  []balancer.SubConn{sc1, sc2, sc1, sc1, sc2, sc1, sc1, sc2, sc3, sc1, sc2, sc1},
+			pass: false,
+		},
+		{
+			desc: "3 elements weighted RR not RR, mistake in second iter",
+			want: []balancer.SubConn{sc1, sc1, sc1, sc2, sc2, sc3},
+			got:  []balancer.SubConn{sc1, sc2, sc3, sc1, sc2, sc1, sc1, sc1, sc3, sc1, sc2, sc1},
+			pass: false,
+		},
+	}
+	for _, tC := range testCases {
+		t.Run(tC.desc, func(t *testing.T) {
+			err := testutils.IsRoundRobin(tC.want, (&testClosure{r: tC.got}).next)
+			if err == nil != tC.pass {
+				t.Errorf("want pass %v, want %v, got err %v", tC.pass, tC.want, err)
+			}
+		})
+	}
+}
+
+// testClosure is a test util for TestIsRoundRobin.
+type testClosure struct {
+	r []balancer.SubConn
+	i int
+}
+
+func (tc *testClosure) next() balancer.SubConn {
+	ret := tc.r[tc.i]
+	tc.i = (tc.i + 1) % len(tc.r)
+	return ret
+}