1.测试例子分析
2.单元测试
1.测试例子分析example_test.go,展示了With-系列的4个例子
func ExampleWithCancel() {
gen := func(ctx context.Context) <-chan int {
dst := make(chan int)
n := 1
go func() {
for {
select {
case <-ctx.Done():
return // returning not to leak the goroutine
case dst <- n:
n++
}
}
}()
return dst
}
ctx, cancel := context.WithCancel(context.Background())
defer cancel() // cancel when we are finished consuming integers
for n := range gen(ctx) {
fmt.Println(n)
if n == 5 {
break
}
}
// Output:
// 1
// 2
// 3
// 4
// 5
}
结构分析,gen
是一个函数,返回值是一个信道, for range channel
是有特殊意义的, for会循环从channel读数据,直到channel被close(),不然就是无限循环.
gen内部的协程就是典型的闭包,for range会不断触发读,gen内部的for select 会不断触发写,主协程读5次之后,会结束main函数,会触发defer函数, 也就是取消操作对应的回调,此时done信道会被close,gen内部的协程会正常退出.
这个例子是测试支持取消信号的上下文,取消函数的调用放在了main
的defer
函数中.
const shortDuration = 1 * time.Millisecond
func ExampleWithDeadline() {
d := time.Now().Add(shortDuration)
ctx, cancel := context.WithDeadline(context.Background(), d)
// Even though ctx will be expired, it is good practice to call its
// cancellation function in any case. Failure to do so may keep the
// context and its parent alive longer than necessary.
defer cancel()
select {
case <-time.After(1 * time.Second):
fmt.Println("overslept")
case <-ctx.Done():
fmt.Println(ctx.Err())
}
// Output:
// context deadline exceeded
}
deadline
的这个例子,在main
的defer
中也有主动调用取消函数的. 实际上通过打印可以显示deadline是否按预期工作.
func ExampleWithTimeout() {
ctx, cancel := context.WithTimeout(context.Background(), shortDuration)
defer cancel()
select {
case <-time.After(1 * time.Second):
fmt.Println("overslept")
case <-ctx.Done():
fmt.Println(ctx.Err()) // prints "context deadline exceeded"
}
// Output:
// context deadline exceeded
}
timeout
只是deadline
的一种简写.
func ExampleWithValue() {
type favContextKey string
f := func(ctx context.Context, k favContextKey) {
if v := ctx.Value(k); v != nil {
fmt.Println("found value:", v)
return
}
fmt.Println("key not found:", k)
}
k := favContextKey("language")
ctx := context.WithValue(context.Background(), k, "Go")
f(ctx, k)
f(ctx, favContextKey("color"))
// Output:
// found value: Go
// key not found: color
}
context.WithValue
和Context.Value()
是存取操作, 取的时候,如果key没找到,会返回nil.
context_text.go,x_test.go
是单元测试, example_test.go
是示例,benchmark_test.go是基准测试, net_test.go展示了deadline对net包的支持.
先看单元测试的context_text.go.
type testingT interface {}
type otherContext struct {}
func quiescent(t testingT) time.Duration {}
func XTestBackground(t testingT) {}
func XTestTODO(t testingT) {}
func XTestWithCancel(t testingT) {}
func contains(m map[canceler]struct{}, key canceler) bool {}
func XTestParentFinishesChild(t testingT) {}
func XTestChildFinishesFirst(t testingT) {}
func testDeadline(c Context, name string, t testingT) {}
func XTestDeadline(t testingT) {}
func XTestTimeout(t testingT) {}
func XTestCanceledTimeout(t testingT) {}
func XTestValues(t testingT) {}
func XTestAllocs(t testingT, testingShort func() bool, testingAllocsPerRun func(int, func()) float64) {}
func XTestSimultaneousCancels(t testingT) {}
func XTestInterlockedCancels(t testingT) {}
func XTestLayersCancel(t testingT) {}
func XTestLayersTimeout(t testingT) {}
func XTestCancelRemoves(t testingT) {}
func XTestWithCancelCanceledParent(t testingT) {}
func XTestWithValueChecksKey(t testingT) {}
func XTestInvalidDerivedFail(t testingT) {}
func recoveredValue(fn func()) (v interface{}) {}
func XTestDeadlineExceededSupportsTimeout(t testingT) {}
type myCtx struct {}
type myDoneCtx struct {}
func (d *myDoneCtx) Done() <-chan struct{} {}
func XTestCustomContextGoroutines(t testingT) {}
这暴露的大多测试函数的参数类型是testingT接口类型,但这个源文件中没有实现testingT
接口的,
func TestBackground(t *testing.T) { XTestBackground(t) }
func TestTODO(t *testing.T) { XTestTODO(t) }
func TestWithCancel(t *testing.T) { XTestWithCancel(t) }
func TestParentFinishesChild(t *testing.T) { XTestParentFinishesChild(t) }
func TestChildFinishesFirst(t *testing.T) { XTestChildFinishesFirst(t) }
func TestDeadline(t *testing.T) { XTestDeadline(t) }
func TestTimeout(t *testing.T) { XTestTimeout(t) }
func TestCanceledTimeout(t *testing.T) { XTestCanceledTimeout(t) }
func TestValues(t *testing.T) { XTestValues(t) }
func TestAllocs(t *testing.T) { XTestAllocs(t, testing.Short, testing.AllocsPerRun) }
func TestSimultaneousCancels(t *testing.T) { XTestSimultaneousCancels(t) }
func TestInterlockedCancels(t *testing.T) { XTestInterlockedCancels(t) }
func TestLayersCancel(t *testing.T) { XTestLayersCancel(t) }
func TestLayersTimeout(t *testing.T) { XTestLayersTimeout(t) }
func TestCancelRemoves(t *testing.T) { XTestCancelRemoves(t) }
func TestWithCancelCanceledParent(t *testing.T) { XTestWithCancelCanceledParent(t) }
func TestWithValueChecksKey(t *testing.T) { XTestWithValueChecksKey(t) }
func TestInvalidDerivedFail(t *testing.T) { XTestInvalidDerivedFail(t) }
func TestDeadlineExceededSupportsTimeout(t *testing.T) { XTestDeadlineExceededSupportsTimeout(t) }
func TestCustomContextGoroutines(t *testing.T) { XTestCustomContextGoroutines(t) }
这是x_test.go
的内容,直接是用testing.T
类型来实现testingT接口.
那先分析一下testing.T对testingT接口的实现.
type T struct {
common
isParallel bool
context *testContext
}
func (t *T) Deadline() (deadline time.Time, ok bool) {
deadline = t.context.deadline
return deadline, !deadline.IsZero()
}
注意:testing.T.context不是context.Context的实现类型, Deadline()返回了t.context中存储的deadline信息.
testing.T内嵌了testing.common,大部分方法集都来至common:
Error(args ...interface{})
Errorf(format string, args ...interface{})
Fail()
FailNow()
Failed() bool
Fatal(args ...interface{})
Fatalf(format string, args ...interface{})
Helper()
Log(args ...interface{})
Logf(format string, args ...interface{})
Name() string
Skip(args ...interface{})
SkipNow()
Skipf(format string, args ...interface{})
Skipped() bool
Parallel()
是由testing.T
实现,某个测试用例多次重复执行时, 可启用并发参数.
到此这篇关于Go语言context test源码分析详情的文章就介绍到这了,更多相关Go语言context test源码分析内容请搜索易知道(ezd.cc)以前的文章或继续浏览下面的相关文章希望大家以后多多支持易知道(ezd.cc)!