C＃8.0单元测试开关表达式未涵盖

编程问答 2022-08-13

问题描述

我正在使用C＃8.0，它为我的项目支持开关表达式。我最近正在构建一个单元测试项目并生成代码覆盖率报告。但是所有开关表达式似乎都存在问题。我的代码中有些行类似于以下内容：

private static string GenerateRequestUrl(Language language,WeatherDataType dataType) {
    var url = "https://data.weather.gov.hk/weatherAPI/Opendata/weather.PHP?";

    url += language switch {
        Language.English => "lang=en",Language.TraditionalChinese => "lang=tc",Language.SimplifiedChinese => "lang=sc",_ => "lang=en"
    };

    url += dataType switch {
        WeatherDataType.LocalWeatherForecast => "&dataType=flw",WeatherDataType.NineDaysWeather => "&dataType=fnd"
    };

    return url;
}

我的测试方法涵盖了上面的所有情况，但是报告显示那些带有switch表达式的行未被覆盖。就像这张图片： Coverage Highlights in JetBrains Rider

我应该怎么做才能掩盖它们。

解决方法

尽管这可能不是您所希望的答案，但似乎代码覆盖率不适用于非顺序开关表达式。

当您查看IL代码时，新的C＃8.0开关表达式首先计算（跳转）该表达式为true，然后设置url。
顺序切换语句在case语句之后设置url。

因此，如果要全面介绍，则应使用顺序切换语句（例如下面代码中的WeatherDataType）。

代码

enter image description here

IL代码 

    .method public hidebysig static string  GenerateRequestUrl(valuetype Demo.Generator/Language language,valuetype Demo.Generator/WeatherDataType dataType) cil managed
{
  // Code size       130 (0x82)
  .maxstack  2
  .locals init (string V_0,string V_1,string V_2,valuetype Demo.Generator/WeatherDataType V_3,valuetype Demo.Generator/WeatherDataType V_4,string V_5)
  IL_0000:  nop
  IL_0001:  ldstr      "https://data.weather.gov.hk/weatherAPI/opendata/we"
  + "ather.php\?"
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  stloc.1
  IL_0009:  ldc.i4.1
  IL_000a:  brtrue.s   IL_000d
  IL_000c:  nop
  IL_000d:  ldarg.0
  IL_000e:  switch     ( 
                        IL_0021,IL_0029,IL_0031)
  IL_001f:  br.s       IL_0039
  IL_0021:  ldstr      "lang=en"
  IL_0026:  stloc.2
  IL_0027:  br.s       IL_0041
  IL_0029:  ldstr      "lang=tc"
  IL_002e:  stloc.2
  IL_002f:  br.s       IL_0041
  IL_0031:  ldstr      "lang=sc"
  IL_0036:  stloc.2
  IL_0037:  br.s       IL_0041
  IL_0039:  ldstr      "lang=en"
  IL_003e:  stloc.2
  IL_003f:  br.s       IL_0041
  IL_0041:  ldc.i4.1
  IL_0042:  brtrue.s   IL_0045
  IL_0044:  nop
  IL_0045:  ldloc.1
  IL_0046:  ldloc.2
  IL_0047:  call       string [System.Runtime]System.String::Concat(string,string)
  IL_004c:  stloc.0
  IL_004d:  ldarg.1
  IL_004e:  stloc.s    V_4
  IL_0050:  ldloc.s    V_4
  IL_0052:  stloc.3
  IL_0053:  ldloc.3
  IL_0054:  brfalse.s  IL_005e
  IL_0056:  br.s       IL_0058
  IL_0058:  ldloc.3
  IL_0059:  ldc.i4.1
  IL_005a:  beq.s      IL_006c
  IL_005c:  br.s       IL_007a
  IL_005e:  ldloc.0
  IL_005f:  ldstr      "&dataType=flw"
  IL_0064:  call       string [System.Runtime]System.String::Concat(string,string)
  IL_0069:  stloc.0
  IL_006a:  br.s       IL_007a
  IL_006c:  ldloc.0
  IL_006d:  ldstr      "&dataType=fnd"
  IL_0072:  call       string [System.Runtime]System.String::Concat(string,string)
  IL_0077:  stloc.0
  IL_0078:  br.s       IL_007a
  IL_007a:  ldloc.0
  IL_007b:  stloc.s    V_5
  IL_007d:  br.s       IL_007f
  IL_007f:  ldloc.s    V_5
  IL_0081:  ret
} // end of method Generator::GenerateRequestUrl
c#c#code-coverageunit-testing