Golang 函数：如何在测试中模拟上下文取消

ctx, cancel := context.WithCancel(context.Background())

cancel()

func ReadValues(ctx context.Context, ch <-chan int) <-chan int {
    out := make(chan int)
    go func() {
        for {
            select {
            case <-ctx.Done():
                close(out)
                return
            case v := <-ch:
                out <- v
            }
        }
    }()
    return out
}

func TestReadValues(t *testing.T) {
    ctx, cancel := context.WithCancel(context.Background())
    values := []int{1, 2, 3}
    ch := make(chan int, len(values))
    for _, v := range values {
        ch <- v
    }

    out := ReadValues(ctx, ch)

    // 接收通道中的值，直到上下文被取消
    received := []int{}
    for v := range out {
        received = append(received, v)
    }

    // 检查收到的值
    if !reflect.DeepEqual(received, values) {
        t.Errorf("Received values do not match expected values")
    }

    // 取消上下文
    cancel()
}