参考了《Go in Action》、《Go 网络编程：使用 Handler 和 HandlerFunc》《golang中 type func() 用法分析》、《net/http/httptest (net/http) - Go 中文开发手册 - 开发者手册》
1 单元测试
单元测试是用来测试包或者程序的一部分代码或者一组代码的函数。go语言中有几种方法编写单元测试：
基础测试（basic test） 只使用一组参数和结果来测试一段代码
表组测试（table test） 使用多组参数和结果进行测试，也可以使用一些方法来模仿（mock）测试代码需要的外部资源。
1.1 基础单元测试
go的测试工具会认为以
_test.go为结尾的文件是测试文件在测试时要引入
testing工具包一个测试函数必须以
Test开头，并且必须接受一个testing.T类型的指针，并且不返回任何值
t的几种常用用法：
t.Log()系列函数：输出测试的消息，如果执行go test的时候没有加入-v参数，我们不会看到任何输出（除非执行失败）t.Fatal()系列函数：报告单元测试执行失败，同时会输出一些消息，并立刻停止测试函数的执行t.Error()系列函数：会输出一些消息，但是不会停止测试函数的执行
如果测试函数没有执行过t.Fatal()和t.Error()，就会认为测试执行通过。
1.2 模仿调用（Mocking）
由于在测试时，未必总是能够得到相应的测试环境，因此有时可以进行一些模拟环境的建立（例如联网），一个有意思的例子可以参考下面的代码：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n223" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">import (
"encoding/xml"
"fmt"
"net/http"
"net/http/httptest"
"testing"
)
const checkMark = "\u2713"
const ballotX = "\u2717"
var feed = <?xml version="1.0" encoding="UTF-8"?> <rss> <channel> <title>Going Go Programming</title> <description>Golang : https://github.com/goinggo</description> <link>http://www.goinggo.net/</link> <item> <pubDate>Sun, 15 Mar 2015 15:04:00 +0000</pubDate> <title>Object Oriented Programming Mechanics</title> <description>Go is an object oriented language.</description> <link>http://www.goinggo.net/2015/03/object-oriented</link> </item> </channel> </rss>
func mockServer() *httptest.Server {
f := func(w http.ResponseWriter, r *http.Request){
w.WriteHeader(200)
w.Header().Set("Content-Type", "application/xml")
fmt.Fprintln(w, feed)
}
return httptest.NewServer(http.HandlerFunc(f))
}</pre>
在上述代码中，用feed变量表示从服务器返回的RSS XML字符串。
核心的代码则是在函数mockServer中，该函数返回一个httptest.Server类型的指针。在该函数中，首先声明了一个符合http.HandlerFunc签名的匿名函数，使其能够处理http请求。之后，利用httptest.NewServer函数，来创建模拟服务器。创建好了模拟服务器以后，就应该将其测试代码进行合并：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n287" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func TestDownload(t *testing.T){
statusCode := http.StatusOK
server := mockServer()
defer server.Close()
t.Log("Given the need to test downloading content.")
{
t.Logf("\tWhen Checking "%s" for status code "%d"", server.URL, statusCode)
{
resp, err := http.Get(server.URL)
if err != nil {
t.Fatal("\t\tShould be able to make the Get call.", ballotX, err)
}
t.Log("\t\tShould be able to make the Get call.", checkMark)
defer resp.Body.Close()
if resp.StatusCode != statusCode{
t.Fatalf("\t\tShould receive a "%d" status. %v %v", stautsCode, ballotX, resp.StatusCode)
}
t.Logf("\t\tShould receive a "%d" status. %v", statusCode, checkMark)
}
}
}</pre>
1.3 测试服务端点
服务端点（endpoint）是指与服务宿主信息无关，用来分辨某个服务的地址，一般是不包含宿主的一个路径。如果在构造网络API，你会希望直接测试自己的服务的所有服务端点，而不用重启整个网络服务。
这段我没看懂，先记录下来什么是
测试端点
2 示例
示例主要用于展示某个函数或者方法的正确使用方法，在go中可以通过代码来自动生成godoc中的示例。需要注意的是，示例代码：
必须以
Example开头必须基于已经存在的公开函数或方法
需要将程序最终的输出和示例函数底部的列出的输出做比较。如果两者匹配，这个示例就会作为测试通过，并加入到go的文档中。如果输出不匹配，这个示例就会作为测试失败，例如：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n416" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">fmt.Println(u)
// Output :
// {Bill bill@ardanstudios.com}</pre>
3 基准测试
基准测试是一种测试代码性能的方法，例如可以用于测试解决同一问题的不同方案的性能，就可以使用基准测试。
基准测试的几个要点如下：
文件名必须以
_test结尾必须导入
testing包基准测试函数必须以
Benchmark开头基准测试函数接受一个指向
testing.B类型的指针作为唯一参数为了能够准确测试函数的性能，必须在一段时间内反复运行一段代码：
<pre mdtype="fences" cid="n536" lang="go" class="md-fences md-end-block ty-contain-cm modeLoaded" spellcheck="false" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">for i := 0; i < b.N; i++{
//测试函数
}</pre>
- 如果只希望运行基准测试函数，则需要加入
-bench选项（该参数接受正则表达式），例如：
<pre mdtype="fences" cid="n548" lang="bash" class="md-fences md-end-block ty-contain-cm modeLoaded" spellcheck="false" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">go test -v -run="none" -bench="<名字>"</pre>
-
-benchtime参数可以用于指定测试执行的最短时间
<pre mdtype="fences" cid="n555" lang="bash" class="md-fences md-end-block ty-contain-cm modeLoaded" spellcheck="false" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">go test -v -run="none" -bench=<正则表达式> -benchtime="3s"</pre>
-
b.ResetTimer()用于重置计时器
基准测试默认会在1s中之内对需要测试的函数反复调用。
-
-benchmenm用于查看提供每次操作分配内存的次数
附1：HandlerFunc、HandleFunc、Handler
附1.1 http.HandleFunc和http.Handle
http.Handle
http.Handle的函数声明为：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n350" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func Handle(pattern string, handler Handler) {
DefaultServeMux.Handle(pattern, handler)
}</pre>
其中：
pattern：路由字符串
handler：处理函数
Handler本质上是一个接口，其中包含一个ServeHttp()方法，其定义为：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n358" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">type Handler interface {
ServeHTTP(ResponseWriter, *Request)
}</pre>
http.HandleFunc
http.HandleFunc接受两个参数：
pattern：路由字符串
handler：
func(ResponseWriter, *Request)类型的函数
其定义为：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n367" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
DefaultServeMux.HandleFunc(pattern, handler)
}</pre>
其中调用了DefaultServeMux.HandleFunc()函数：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n369" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
mux.Handle(pattern, HandlerFunc(handler))
}</pre>
其中，
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n371" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">type HandlerFunc func(ResponseWriter, *Request)
func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
f(w, r)
}</pre>
附1.2 HandlerFunc
HandlerFunc的声明如下：
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="go" cid="n232" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">type HandlerFunc func(ResponseWriter, *Request)</pre>
根据HandlerFunc的声明可知，http.HandlerFunc是一个适配器，其能够使常规函数作为HTTP的请求处理函数。只要函数f具有合适的签名，HandlerFunc(f)就是一个HTTP请求的处理对象。
附2 httptest包
附2.1 httptest.Server
httptest.Server是一个HTTP服务器，它侦听本地环回接口上的系统选择端口，用于端到端的HTTP测试。 其定义为：
<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="go" cid="n273" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">type Server struct {
URL string // base URL of form http://ipaddr:port with no trailing slash
Listener net.Listener
// TLS is the optional TLS configuration, populated with a new config
// after TLS is started. If set on an unstarted server before StartTLS
// is called, existing fields are copied into the new config.
TLS *tls.Config
// Config may be changed after calling NewUnstartedServer and
// before Start or StartTLS.
Config *http.Server
// contains filtered or unexported fields
}</pre>
附2.2 httptest.NewServer()
httptest.NewServer()启动并返回一个新的服务器。调用者在完成时应该调用Close来关闭它。其声明为：
<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="go" cid="n284" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func NewServer(handler http.Handler) *Server</pre>
附2.3 httptest.ResponseRecorder
httptest.ResponseRecorder是http.ResponseWriter的一个实现，它记录了其突变，以便在测试中进行后续检查。其定义为：
<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="go" cid="n378" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">type ResponseRecorder struct {
// Code is the HTTP response code set by WriteHeader.
//
// Note that if a Handler never calls WriteHeader or Write,
// this might end up being 0, rather than the implicit
// http.StatusOK. To get the implicit value, use the Result
// method.
Code int
// HeaderMap contains the headers explicitly set by the Handler.
//
// To get the implicit headers set by the server (such as
// automatic Content-Type), use the Result method.
HeaderMap http.Header
// Body is the buffer to which the Handler's Write calls are sent.
// If nil, the Writes are silently discarded.
Body *bytes.Buffer
// Flushed is whether the Handler called Flush.
Flushed bool
// contains filtered or unexported fields
}</pre>
附2.4 httptest.NewRecoder()
生成并返回一个初始化的httptest.ResponseRecorder对象，其声明为：
<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="go" cid="n387" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">func NewRecorder() *ResponseRecorder</pre>
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