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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 单元测试和基准测试</title>
<link rel=stylesheet href="site.css">
</head>
<script>
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<body>
<div class="example" id="testing-and-benchmarking">
<h2><a href="./">Go by Example 中文版</a>: 单元测试和基准测试</h2>
<table>
<tr>
<td class="docs">
<p>想要写出好的 Go 程序，单元测试是很重要的一部分。
<code>testing</code> 包为提供了编写单元测试所需的工具，写好单元测试后，我们可以通过 <code>go test</code> 命令运行测试。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
<p>为方便演示，例子的代码位于 <code>main</code> 包，实际上，单元测试的代码可以位于任何包下。
测试代码通常与需要被测试的代码位于同一个包下。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/6_USpbeJGKP"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"fmt"</span>
<span class="s">"testing"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>我们要测试下面这个简单的函数——返回最小值。
一般地，需要被测试的代码应该在类似于 <code>intutils.go</code> 的文件下，
其对应的测试文件应该被命名为 <code>intutils_test.go</code>。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">IntMin</span><span class="p">(</span><span class="nx">a</span><span class="p">,</span> <span class="nx">b</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
<span class="k">if</span> <span class="nx">a</span> <span class="p"><</span> <span class="nx">b</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">a</span>
<span class="p">}</span>
<span class="k">return</span> <span class="nx">b</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>通常编写一个名称以 <code>Test</code> 开头的函数来创建测试。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">TestIntMinBasic</span><span class="p">(</span><span class="nx">t</span> <span class="o">*</span><span class="nx">testing</span><span class="p">.</span><span class="nx">T</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">ans</span> <span class="o">:=</span> <span class="nf">IntMin</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="o">-</span><span class="mi">2</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">ans</span> <span class="o">!=</span> <span class="o">-</span><span class="mi">2</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>t.Error*</code> 会报告测试失败的信息，然后继续运行测试。
<code>t.Fatal*</code> 会报告测试失败的信息，然后立即终止测试。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t</span><span class="p">.</span><span class="nf">Errorf</span><span class="p">(</span><span class="s">"IntMin(2, -2) = %d; want -2"</span><span class="p">,</span> <span class="nx">ans</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>单元测试可以重复，所以会经常使用 <em>表驱动</em> 风格编写单元测试，
表中列出了输入数据，预期输出，使用循环，遍历并执行测试逻辑。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">TestIntMinTableDriven</span><span class="p">(</span><span class="nx">t</span> <span class="o">*</span><span class="nx">testing</span><span class="p">.</span><span class="nx">T</span><span class="p">)</span> <span class="p">{</span>
<span class="kd">var</span> <span class="nx">tests</span> <span class="p">=</span> <span class="p">[]</span><span class="kd">struct</span> <span class="p">{</span>
<span class="nx">a</span><span class="p">,</span> <span class="nx">b</span> <span class="kt">int</span>
<span class="nx">want</span> <span class="kt">int</span>
<span class="p">}{</span>
<span class="p">{</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">},</span>
<span class="p">{</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">},</span>
<span class="p">{</span><span class="mi">2</span><span class="p">,</span> <span class="o">-</span><span class="mi">2</span><span class="p">,</span> <span class="o">-</span><span class="mi">2</span><span class="p">},</span>
<span class="p">{</span><span class="mi">0</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">},</span>
<span class="p">{</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">},</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>t.Run 可以运行一个 “subtests” 子测试，一个子测试对应表中一行数据。
运行 <code>go test -v</code> 时，他们会分开显示。</p>
</td>
<td class="code leading">
<pre class="chroma"> <span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">tt</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">tests</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"> <span class="nx">testname</span> <span class="o">:=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nf">Sprintf</span><span class="p">(</span><span class="s">"%d,%d"</span><span class="p">,</span> <span class="nx">tt</span><span class="p">.</span><span class="nx">a</span><span class="p">,</span> <span class="nx">tt</span><span class="p">.</span><span class="nx">b</span><span class="p">)</span>
<span class="nx">t</span><span class="p">.</span><span class="nf">Run</span><span class="p">(</span><span class="nx">testname</span><span class="p">,</span> <span class="kd">func</span><span class="p">(</span><span class="nx">t</span> <span class="o">*</span><span class="nx">testing</span><span class="p">.</span><span class="nx">T</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">ans</span> <span class="o">:=</span> <span class="nf">IntMin</span><span class="p">(</span><span class="nx">tt</span><span class="p">.</span><span class="nx">a</span><span class="p">,</span> <span class="nx">tt</span><span class="p">.</span><span class="nx">b</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">ans</span> <span class="o">!=</span> <span class="nx">tt</span><span class="p">.</span><span class="nx">want</span> <span class="p">{</span>
<span class="nx">t</span><span class="p">.</span><span class="nf">Errorf</span><span class="p">(</span><span class="s">"got %d, want %d"</span><span class="p">,</span> <span class="nx">ans</span><span class="p">,</span> <span class="nx">tt</span><span class="p">.</span><span class="nx">want</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">})</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>基准测试通常在”_test.go”文件中，并以 <code>Benchmark</code> 开头命名。
<code>testing</code> 运行器多次执行每个基准测试函数，并在每次运行时增加 <code>b.N</code>，
直到它收集到精确的测量值。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">BenchmarkIntMin</span><span class="p">(</span><span class="nx">b</span> <span class="o">*</span><span class="nx">testing</span><span class="p">.</span><span class="nx">B</span><span class="p">)</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>通常，基准测试运行一个函数，我们在一个 <code>b.N</code> 次的循环内进行基准测试。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="nx">b</span><span class="p">.</span><span class="nx">N</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nf">IntMin</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>以啰嗦模式运行当前项目下的所有测试。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> go test -v
<span class="go">== RUN TestIntMinBasic
</span><span class="go">--- PASS: TestIntMinBasic (0.00s)
</span><span class="go">=== RUN TestIntMinTableDriven
</span><span class="go">=== RUN TestIntMinTableDriven/0,1
</span><span class="go">=== RUN TestIntMinTableDriven/1,0
</span><span class="go">=== RUN TestIntMinTableDriven/2,-2
</span><span class="go">=== RUN TestIntMinTableDriven/0,-1
</span><span class="go">=== RUN TestIntMinTableDriven/-1,0
</span><span class="go">--- PASS: TestIntMinTableDriven (0.00s)
</span><span class="go"> --- PASS: TestIntMinTableDriven/0,1 (0.00s)
</span><span class="go"> --- PASS: TestIntMinTableDriven/1,0 (0.00s)
</span><span class="go"> --- PASS: TestIntMinTableDriven/2,-2 (0.00s)
</span><span class="go"> --- PASS: TestIntMinTableDriven/0,-1 (0.00s)
</span><span class="go"> --- PASS: TestIntMinTableDriven/-1,0 (0.00s)
</span><span class="go">PASS
</span><span class="go">ok examples/testing-and-benchmarking 0.023s</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>运行当前项目中的所有基准测试。所有测试都在基准测试之前运行。
<code>bench</code> 标志使用正则表达式过滤基准函数名称。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="gp">$</span> go test -bench=.
<span class="go">goos: darwin
</span><span class="go">goarch: arm64
</span><span class="go">pkg: examples/testing
</span><span class="go">BenchmarkIntMin-8 1000000000 0.3136 ns/op
</span><span class="go">PASS
</span><span class="go">ok examples/testing-and-benchmarking 0.351s</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="command-line-arguments">命令行参数</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
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