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// Copyright 2017 Canonical Ltd.
//
// 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 election_test
import (
"strconv"
"testing"
"time"
"github.com/CanonicalLtd/raft-test/internal/election"
"github.com/CanonicalLtd/raft-test/internal/logging"
"github.com/hashicorp/raft"
"github.com/stretchr/testify/assert"
)
// Observe that a given server has acquired leadership.
func TestTracker_Acquired(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
n := 3
notifyChs := make([]chan bool, n)
for i := 0; i < n; i++ {
id := raft.ServerID(strconv.Itoa(i))
notifyChs[i] = make(chan bool)
tracker.Track(id, notifyChs[i])
}
future := tracker.Expect("0", 100*time.Millisecond)
notifyChs[0] <- true
_, err := future.Done()
assert.NoError(t, err)
}
// If leadership is not acquired within the given timeout, an error is returned.
func TestTracker_AcquiredTimeout(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
tracker.Track("0", make(chan bool))
future := tracker.Expect("0", time.Nanosecond)
_, err := future.Done()
assert.EqualError(t, err, "server 0: leadership not acquired within 1ns")
}
// While a server has acquired leadership, it's not possible to make another
// acquire request.
func TestTracker_AcquiredTwice(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
n := 3
notifyChs := make([]chan bool, n)
for i := 0; i < n; i++ {
id := raft.ServerID(strconv.Itoa(i))
notifyChs[i] = make(chan bool)
tracker.Track(id, notifyChs[i])
}
future := tracker.Expect("0", 100*time.Millisecond)
notifyChs[0] <- true
_, err := future.Done()
assert.NoError(t, err)
f := func() {
tracker.Expect("1", time.Millisecond)
}
assert.PanicsWithValue(t, "server 0 has already requested leadership", f)
}
// After a first leadership has completed, it's possible to observe a new one.
func TestTracker_AcquiredAfterLost(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
n := 3
notifyChs := make([]chan bool, n)
for i := 0; i < n; i++ {
id := raft.ServerID(strconv.Itoa(i))
notifyChs[i] = make(chan bool)
tracker.Track(id, notifyChs[i])
}
future := tracker.Expect("0", 100*time.Millisecond)
notifyChs[0] <- true
leadership, err := future.Done()
assert.NoError(t, err)
notifyChs[0] <- false
<-leadership.Lost()
tracker.Expect("1", time.Nanosecond)
}
// It's not possible to add two trackers for the same server.
func TestTracker_AddSameServerID(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
tracker.Track("0", make(chan bool, 1))
f := func() {
tracker.Track("0", make(chan bool, 1))
}
assert.PanicsWithValue(t, "an observer for server 0 is already registered", f)
}
// After the tracker has been used to acquire leadership, it's not possible to
// add more server trackers.
func TestTracker_AddAfterObserving(t *testing.T) {
tracker := newTestTracker(t)
defer tracker.Close()
tracker.Track("0", make(chan bool, 1))
tracker.Expect("0", 100*time.Millisecond)
f := func() {
tracker.Track("1", make(chan bool, 1))
}
assert.PanicsWithValue(t, "can't track new server while observing", f)
}
func newTestTracker(t testing.TB) *election.Tracker {
logger := logging.New(t, "DEBUG")
return election.NewTracker(logger)
}
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