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< ol class = "chapter" > < li class = "chapter-item expanded affix " > < a href = "../index.html" > Go语言圣经< / a > < / li > < li class = "chapter-item expanded affix " > < a href = "../preface.html" > 前言< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1.html" > < strong aria-hidden = "true" > 1.< / strong > 入门< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-01.html" > < strong aria-hidden = "true" > 1.1.< / strong > Hello, World< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-02.html" > < strong aria-hidden = "true" > 1.2.< / strong > 命令行参数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-03.html" > < strong aria-hidden = "true" > 1.3.< / strong > 查找重复的行< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-04.html" > < strong aria-hidden = "true" > 1.4.< / strong > GIF动画< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-05.html" > < strong aria-hidden = "true" > 1.5.< / strong > 获取URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-06.html" > < strong aria-hidden = "true" > 1.6.< / strong > 并发获取多个URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-07.html" > < strong aria-hidden = "true" > 1.7.< / strong > Web服务< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-08.html" > < strong aria-hidden = "true" > 1.8.< / strong > 本章要点< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2.html" > < strong aria-hidden = "true" > 2.< / strong > 程序结构< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-01.html" > < strong aria-hidden = "true" > 2.1.< / strong > 命名< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-02.html" > < strong aria-hidden = "true" > 2.2.< / strong > 声明< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-03.html" > < strong aria-hidden = "true" > 2.3.< / strong > 变量< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-04.html" > < strong aria-hidden = "true" > 2.4.< / strong > 赋值< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-05.html" > < strong aria-hidden = "true" > 2.5.< / strong > 类型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-06.html" > < strong aria-hidden = "true" > 2.6.< / strong > 包和文件< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-07.html" > < strong aria-hidden = "true" > 2.7.< / strong > 作用域< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3.html" > < strong aria-hidden = "true" > 3.< / strong > 基础数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-01.html" > < strong aria-hidden = "true" > 3.1.< / strong > 整型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-02.html" > < strong aria-hidden = "true" > 3.2.< / strong > 浮点数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-03.html" > < strong aria-hidden = "true" > 3.3.< / strong > 复数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-04.html" > < strong aria-hidden = "true" > 3.4.< / strong > 布尔型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-05.html" > < strong aria-hidden = "true" > 3.5.< / strong > 字符串< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-06.html" > < strong aria-hidden = "true" > 3.6.< / strong > 常量< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4.html" > < strong aria-hidden = "true" > 4.< / strong > 复合数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-01.html" > < strong aria-hidden = "true" > 4.1.< / strong > 数组< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-02.html" > < strong aria-hidden = "true" > 4.2.< / strong > Slice< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-03.html" > < strong aria-hidden = "true" > 4.3.< / strong > Map< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-04.html" > < strong aria-hidden = "true" > 4.4.< / strong > 结构体< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-05.html" > < strong aria-hidden = "true" > 4.5.< / strong > JSON< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-06.html" > < strong aria-hidd
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2022-08-24 10:48:15 +00:00
< li > < em > KusonStack一站式可编程配置技术栈(Go): < a href = "https://github.com/KusionStack/kusion" > https://github.com/KusionStack/kusion< / a > < / em > < / li >
< li > < em > KCL 配置编程语言(Rust): < a href = "https://github.com/KusionStack/KCLVM" > https://github.com/KusionStack/KCLVM< / a > < / em > < / li >
< li > < em > 凹语言™: < a href = "https://github.com/wa-lang/wa" > https://github.com/wa-lang/wa< / a > < / em > < / li >
2022-08-04 06:59:33 +00:00
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< hr >
< h2 id = "113-测试覆盖率" > < a class = "header" href = "#113-测试覆盖率" > 11.3. 测试覆盖率< / a > < / h2 >
< p > 就其性质而言， ： ， ， ： < / p >
< p > 对待测程序执行的测试的程度称为测试的覆盖率。测试覆盖率并不能量化——即使最简单的程序的动态也是难以精确测量的——但是有启发式方法来帮助我们编写有效的测试代码。< / p >
< p > 这些启发式方法中，语句的覆盖率是最简单和最广泛使用的。语句的覆盖率是指在测试中至少被运行一次的代码占总代码数的比例。在本节中，我们使用< code > go test< / code > 命令中集成的测试覆盖率工具，来度量下面代码的测试覆盖率，帮助我们识别测试和我们期望间的差距。< / p >
< p > 下面的代码是一个表格驱动的测试，用于测试第七章的表达式求值程序：< / p >
< p > < u > < i > gopl.io/ch7/eval< / i > < / u > < / p >
< pre > < code class = "language-Go" > func TestCoverage(t *testing.T) {
var tests = []struct {
input string
env Env
want string // expected error from Parse/Check or result from Eval
}{
{" x % 2" , nil, " unexpected '%'" },
{" !true" , nil, " unexpected '!'" },
{" log(10)" , nil, `unknown function " log" `},
{" sqrt(1, 2)" , nil, " call to sqrt has 2 args, want 1" },
{" sqrt(A / pi)" , Env{" A" : 87616, " pi" : math.Pi}, " 167" },
{" pow(x, 3) + pow(y, 3)" , Env{" x" : 9, " y" : 10}, " 1729" },
{" 5 / 9 * (F - 32)" , Env{" F" : -40}, " -40" },
}
for _, test := range tests {
expr, err := Parse(test.input)
if err == nil {
err = expr.Check(map[Var]bool{})
}
if err != nil {
if err.Error() != test.want {
t.Errorf(" %s: got %q, want %q" , test.input, err, test.want)
}
continue
}
got := fmt.Sprintf(" %.6g" , expr.Eval(test.env))
if got != test.want {
t.Errorf(" %s: %v => %s, want %s" ,
test.input, test.env, got, test.want)
}
}
}
< / code > < / pre >
< p > 首先，我们要确保所有的测试都正常通过：< / p >
< pre > < code > $ go test -v -run=Coverage gopl.io/ch7/eval
=== RUN TestCoverage
--- PASS: TestCoverage (0.00s)
PASS
ok gopl.io/ch7/eval 0.011s
< / code > < / pre >
< p > 下面这个命令可以显示测试覆盖率工具的使用用法：< / p >
< pre > < code > $ go tool cover
Usage of 'go tool cover':
Given a coverage profile produced by 'go test':
go test -coverprofile=c.out
Open a web browser displaying annotated source code:
go tool cover -html=c.out
...
< / code > < / pre >
< p > < code > go tool< / code > 命令运行Go工具链的底层可执行程序。这些底层可执行程序放在$GOROOT/pkg/tool/${GOOS}_${GOARCH}目录。因为有< code > go build< / code > 命令的原因，我们很少直接调用这些底层工具。< / p >
< p > 现在我们可以用< code > -coverprofile< / code > 标志参数重新运行测试：< / p >
< pre > < code > $ go test -run=Coverage -coverprofile=c.out gopl.io/ch7/eval
ok gopl.io/ch7/eval 0.032s coverage: 68.5% of statements
< / code > < / pre >
< p > 这个标志参数通过在测试代码中插入生成钩子来统计覆盖率数据。也就是说， ， ， ， ， （ ， < code > go test -cover< / code > 。）< / p >
< p > 如果使用了< code > -covermode=count< / code > 标志参数，那么将在每个代码块插入一个计数器而不是布尔标志量。在统计结果中记录了每个块的执行次数，这可以用于衡量哪些是被频繁执行的热点代码。< / p >
< p > 为了收集数据， ， ， ， （ < / p >
< pre > < code > $ go tool cover -html=c.out
< / code > < / pre >
< p > < img src = "../images/ch11-03.png" alt = "" / > < / p >
< p > 绿色的代码块被测试覆盖到了， ， ， ， ： < / p >
< pre > < code > {" -x * -x" , eval.Env{" x" : 2}, " 4" }
< / code > < / pre >
< p > 不过两个panic语句依然是红色的。这是没有问题的， < / p >
< p > 实现100%的测试覆盖率听起来很美， ， ， ； ， ， ， ， < / p >
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