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/*
Copyright 2012 Google Inc.
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 singleflight
import (
"errors"
"fmt"
"sync"
"sync/atomic"
"testing"
"time"
)
func TestDo(t *testing.T) {
var g Group
v, err := g.Do("key", func() (interface{}, error) {
return "bar", nil
})
if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
t.Errorf("Do = %v; want %v", got, want)
}
if err != nil {
t.Errorf("Do error = %v", err)
}
}
func TestDoErr(t *testing.T) {
var g Group
someErr := errors.New("Some error")
v, err := g.Do("key", func() (interface{}, error) {
return nil, someErr
})
if err != someErr {
t.Errorf("Do error = %v; want someErr", err)
}
if v != nil {
t.Errorf("unexpected non-nil value %#v", v)
}
}
func TestDoDupSuppress(t *testing.T) {
var g Group
c := make(chan string)
var calls int32
fn := func() (interface{}, error) {
atomic.AddInt32(&calls, 1)
return <-c, nil
}
const n = 10
var wg sync.WaitGroup
for i := 0; i < n; i++ {
wg.Add(1)
go func() {
v, err := g.Do("key", fn)
if err != nil {
t.Errorf("Do error: %v", err)
}
if v.(string) != "bar" {
t.Errorf("got %q; want %q", v, "bar")
}
wg.Done()
}()
}
time.Sleep(100 * time.Millisecond) // let goroutines above block
c <- "bar"
wg.Wait()
if got := atomic.LoadInt32(&calls); got != 1 {
t.Errorf("number of calls = %d; want 1", got)
}
}
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