crap-analysis

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CRAP Score Analysis

CRAP分数分析

When to Use This Skill

何时使用该技能

Use this skill when:

Evaluating code quality and test coverage before changes
Identifying high-risk code that needs refactoring or testing
Setting up coverage collection for a .NET project
Prioritizing which code to test based on risk
Establishing coverage thresholds for CI/CD pipelines

在以下场景使用该技能：

在代码变更前评估代码质量和测试覆盖率
识别需要重构或补充测试的高风险代码
为.NET项目设置覆盖率收集配置
根据风险优先级确定测试代码的顺序
为CI/CD流水线设置覆盖率阈值

What is CRAP?

什么是CRAP？

CRAP Score = Complexity x (1 - Coverage)^2

The CRAP (Change Risk Anti-Patterns) score combines cyclomatic complexity with test coverage to identify risky code.

CRAP Score	Risk Level	Action Required
< 5	Low	Well-tested, maintainable code
5-30	Medium	Acceptable but watch complexity
> 30	High	Needs tests or refactoring

CRAP分数 = 圈复杂度 × (1 - 覆盖率)²

CRAP（变更风险反模式）分数结合圈复杂度和测试覆盖率来识别有风险的代码。

CRAP分数	风险等级	所需操作
< 5	低	测试充分、可维护的代码
5-30	中	可接受，但需关注复杂度
> 30	高	需要补充测试或重构

Why CRAP Matters

CRAP的重要性

High complexity + low coverage = danger: Code that's hard to understand AND untested is risky to modify
Complexity alone isn't enough: A complex method with 100% coverage is safer than a simple method with 0%
Focuses effort: Prioritize testing on complex code, not simple getters/setters

高复杂度+低覆盖率=危险: 难以理解且未测试的代码在修改时风险极高
仅看复杂度不够: 一个覆盖率100%的复杂方法比覆盖率0%的简单方法更安全
聚焦工作重点: 优先为复杂代码编写测试，而非简单的getter/setter方法

CRAP Score Examples

CRAP分数示例

Method	Complexity	Coverage	Calculation	CRAP
`GetUserId()`	1	0%	1 x (1 - 0)^2	1
`ParseToken()`	54	52%	54 x (1 - 0.52)^2	12.4
`ValidateForm()`	20	0%	20 x (1 - 0)^2	20
`ProcessOrder()`	45	20%	45 x (1 - 0.20)^2	28.8
`ImportData()`	80	10%	80 x (1 - 0.10)^2	64.8

方法	圈复杂度	覆盖率	计算过程	CRAP分数
`GetUserId()`	1	0%	1 × (1 - 0)²	1
`ParseToken()`	54	52%	54 × (1 - 0.52)²	12.4
`ValidateForm()`	20	0%	20 × (1 - 0)²	20
`ProcessOrder()`	45	20%	45 × (1 - 0.20)²	28.8
`ImportData()`	80	10%	80 × (1 - 0.10)²	64.8

Coverage Collection Setup

覆盖率收集配置

coverage.runsettings

Create a

coverage.runsettings

file in your repository root. The OpenCover format is required for CRAP score calculation because it includes cyclomatic complexity metrics.

xml

<?xml version="1.0" encoding="utf-8" ?>
<RunSettings>
  <DataCollectionRunSettings>
    <DataCollectors>
      <DataCollector friendlyName="XPlat code coverage">
        <Configuration>
          <!-- OpenCover format includes cyclomatic complexity for CRAP scores -->
          <Format>cobertura,opencover</Format>

          <!-- Exclude test and benchmark assemblies -->
          <Exclude>[*.Tests]*,[*.Benchmark]*,[*.Migrations]*</Exclude>

          <!-- Exclude generated code, obsolete members, and explicit exclusions -->
          <ExcludeByAttribute>Obsolete,GeneratedCodeAttribute,CompilerGeneratedAttribute,ExcludeFromCodeCoverageAttribute</ExcludeByAttribute>

          <!-- Exclude source-generated files, Blazor generated code, and migrations -->
          <ExcludeByFile>**/obj/**/*,**/*.g.cs,**/*.designer.cs,**/*.razor.g.cs,**/*.razor.css.g.cs,**/Migrations/**/*</ExcludeByFile>

          <!-- Exclude test projects -->
          <IncludeTestAssembly>false</IncludeTestAssembly>

          <!-- Optimization flags -->
          <SingleHit>false</SingleHit>
          <UseSourceLink>true</UseSourceLink>
          <SkipAutoProps>true</SkipAutoProps>
        </Configuration>
      </DataCollector>
    </DataCollectors>
  </DataCollectionRunSettings>
</RunSettings>

在仓库根目录创建

coverage.runsettings

文件。CRAP分数计算必须使用OpenCover格式，因为它包含圈复杂度指标。

xml

<?xml version="1.0" encoding="utf-8" ?>
<RunSettings>
  <DataCollectionRunSettings>
    <DataCollectors>
      <DataCollector friendlyName="XPlat code coverage">
        <Configuration>
          <!-- OpenCover format includes cyclomatic complexity for CRAP scores -->
          <Format>cobertura,opencover</Format>

          <!-- Exclude test and benchmark assemblies -->
          <Exclude>[*.Tests]*,[*.Benchmark]*,[*.Migrations]*</Exclude>

          <!-- Exclude generated code, obsolete members, and explicit exclusions -->
          <ExcludeByAttribute>Obsolete,GeneratedCodeAttribute,CompilerGeneratedAttribute,ExcludeFromCodeCoverageAttribute</ExcludeByAttribute>

          <!-- Exclude source-generated files, Blazor generated code, and migrations -->
          <ExcludeByFile>**/obj/**/*,**/*.g.cs,**/*.designer.cs,**/*.razor.g.cs,**/*.razor.css.g.cs,**/Migrations/**/*</ExcludeByFile>

          <!-- Exclude test projects -->
          <IncludeTestAssembly>false</IncludeTestAssembly>

          <!-- Optimization flags -->
          <SingleHit>false</SingleHit>
          <UseSourceLink>true</UseSourceLink>
          <SkipAutoProps>true</SkipAutoProps>
        </Configuration>
      </DataCollector>
    </DataCollectors>
  </DataCollectionRunSettings>
</RunSettings>

Key Configuration Options

关键配置选项

Option	Purpose
`Format`	Must include `opencover` for complexity metrics
`Exclude`	Exclude test/benchmark assemblies by pattern
`ExcludeByAttribute`	Skip generated, obsolete, and explicitly excluded code (includes `ExcludeFromCodeCoverageAttribute` )
`ExcludeByFile`	Skip source-generated files, Blazor components, and migrations
`SkipAutoProps`	Don't count auto-properties as branches

选项	用途
`Format`	必须包含 `opencover` 以获取复杂度指标
`Exclude`	通过模式排除测试/基准测试程序集
`ExcludeByAttribute`	跳过生成代码、过时成员和显式排除的代码（包括 `ExcludeFromCodeCoverageAttribute` ）
`ExcludeByFile`	跳过源生成文件、Blazor组件和迁移文件
`SkipAutoProps`	不将自动属性计入分支

ReportGenerator Installation

ReportGenerator安装

Install ReportGenerator as a local tool for generating HTML reports with Risk Hotspots.

安装ReportGenerator作为本地工具，用于生成包含风险热点的HTML报告。

Add to .config/dotnet-tools.json

添加到.config/dotnet-tools.json

json

{
  "version": 1,
  "isRoot": true,
  "tools": {
    "dotnet-reportgenerator-globaltool": {
      "version": "5.4.5",
      "commands": ["reportgenerator"],
      "rollForward": false
    }
  }
}

Then restore:

bash

dotnet tool restore

json

{
  "version": 1,
  "isRoot": true,
  "tools": {
    "dotnet-reportgenerator-globaltool": {
      "version": "5.4.5",
      "commands": ["reportgenerator"],
      "rollForward": false
    }
  }
}

然后执行恢复命令：

bash

dotnet tool restore

Or Install Globally

或全局安装

bash

dotnet tool install --global dotnet-reportgenerator-globaltool

bash

dotnet tool install --global dotnet-reportgenerator-globaltool

Collecting Coverage

收集覆盖率数据

Run Tests with Coverage Collection

运行测试并收集覆盖率

bash

undefined

bash

undefined

Clean previous results

清理之前的结果

rm -rf coverage/ TestResults/

Run unit tests with coverage

运行单元测试并收集覆盖率

dotnet test tests/MyApp.Tests.Unit
--settings coverage.runsettings
--collect:"XPlat Code Coverage"
--results-directory ./TestResults

Run integration tests (optional, adds to coverage)

运行集成测试（可选，会增加覆盖率数据）

dotnet test tests/MyApp.Tests.Integration
--settings coverage.runsettings
--collect:"XPlat Code Coverage"
--results-directory ./TestResults

undefined

dotnet test tests/MyApp.Tests.Integration
--settings coverage.runsettings
--collect:"XPlat Code Coverage"
--results-directory ./TestResults

undefined

Generate HTML Report

生成HTML报告

bash

dotnet reportgenerator \
  -reports:"TestResults/**/coverage.opencover.xml" \
  -targetdir:"coverage" \
  -reporttypes:"Html;TextSummary;MarkdownSummaryGithub"

bash

dotnet reportgenerator \
  -reports:"TestResults/**/coverage.opencover.xml" \
  -targetdir:"coverage" \
  -reporttypes:"Html;TextSummary;MarkdownSummaryGithub"

Report Types

报告类型

Type	Description	Output
`Html`	Full interactive report	`coverage/index.html`
`TextSummary`	Plain text summary	`coverage/Summary.txt`
`MarkdownSummaryGithub`	GitHub-compatible markdown	`coverage/SummaryGithub.md`
`Badges`	SVG badges for README	`coverage/badge_*.svg`
`Cobertura`	Merged Cobertura XML	`coverage/Cobertura.xml`

类型	描述	输出位置
`Html`	完整交互式报告	`coverage/index.html`
`TextSummary`	纯文本摘要	`coverage/Summary.txt`
`MarkdownSummaryGithub`	兼容GitHub的Markdown格式	`coverage/SummaryGithub.md`
`Badges`	用于README的SVG徽章	`coverage/badge_*.svg`
`Cobertura`	合并后的Cobertura XML文件	`coverage/Cobertura.xml`

Reading the Report

报告解读

Risk Hotspots Section

风险热点部分

The HTML report includes a Risk Hotspots section showing methods sorted by complexity:

Cyclomatic Complexity: Number of independent paths through code (if/else, switch cases, loops)
NPath Complexity: Number of acyclic execution paths (exponential growth with nesting)
Crap Score: Calculated from complexity and coverage

HTML报告包含风险热点部分，按复杂度排序展示方法：

Cyclomatic Complexity: 代码中的独立路径数量（if/else、switch分支、循环等）
NPath Complexity: 无环执行路径的数量（嵌套会导致指数级增长）
Crap Score: 由复杂度和覆盖率计算得出的分数

Interpreting Results

结果解读示例

Risk Hotspots
─────────────
Method                          Complexity  Coverage  Crap Score
──────────────────────────────────────────────────────────────────
DataImporter.ParseRecord()      54          52%       12.4
AuthService.ValidateToken()     32          0%        32.0   ← HIGH RISK
OrderProcessor.Calculate()      28          85%       1.3
UserService.CreateUser()        15          100%      0.0

Action items:

```
ValidateToken()
```
has CRAP > 30 with 0% coverage - test immediately or refactor
```
ParseRecord()
```
is complex but has decent coverage - acceptable
```
CreateUser()
```
and
```
Calculate()
```
are well-tested - safe to modify

Risk Hotspots
─────────────
Method                          Complexity  Coverage  Crap Score
──────────────────────────────────────────────────────────────────
DataImporter.ParseRecord()      54          52%       12.4
AuthService.ValidateToken()     32          0%        32.0   ← HIGH RISK
OrderProcessor.Calculate()      28          85%       1.3
UserService.CreateUser()        15          100%      0.0

行动项：

```
ValidateToken()
```
的CRAP分数>30且覆盖率为0% - 立即补充测试或重构
```
ParseRecord()
```
复杂度较高但覆盖率尚可 - 可接受
```
CreateUser()
```
和
```
Calculate()
```
测试充分 - 修改时风险低

Coverage Thresholds

覆盖率阈值

Recommended Standards

Coverage Type	Target	Action
Line Coverage	> 80%	Good for most projects
Branch Coverage	> 60%	Catches conditional logic
CRAP Score	< 30	Maximum for new code

覆盖率类型	目标值	行动
行覆盖率	> 80%	适用于大多数项目
分支覆盖率	> 60%	覆盖条件逻辑测试
CRAP分数	< 30	新代码的最高允许值

Configuring Thresholds

配置阈值

Create

coverage.props

in your repository:

xml

<Project>
  <PropertyGroup>
    <!-- Coverage thresholds for CI enforcement -->
    <CoverageThresholdLine>80</CoverageThresholdLine>
    <CoverageThresholdBranch>60</CoverageThresholdBranch>
  </PropertyGroup>
</Project>

在仓库中创建

coverage.props

文件：

xml

<Project>
  <PropertyGroup>
    <!-- Coverage thresholds for CI enforcement -->
    <CoverageThresholdLine>80</CoverageThresholdLine>
    <CoverageThresholdBranch>60</CoverageThresholdBranch>
  </PropertyGroup>
</Project>

CI/CD Integration

CI/CD集成

GitHub Actions

yaml

name: Coverage

on:
  pull_request:
    branches: [main, dev]

jobs:
  coverage:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '9.0.x'

      - name: Restore tools
        run: dotnet tool restore

      - name: Run tests with coverage
        run: |
          dotnet test \
            --settings coverage.runsettings \
            --collect:"XPlat Code Coverage" \
            --results-directory ./TestResults

      - name: Generate report
        run: |
          dotnet reportgenerator \
            -reports:"TestResults/**/coverage.opencover.xml" \
            -targetdir:"coverage" \
            -reporttypes:"Html;MarkdownSummaryGithub;Cobertura"

      - name: Upload coverage report
        uses: actions/upload-artifact@v4
        with:
          name: coverage-report
          path: coverage/

      - name: Add coverage to PR
        uses: marocchino/sticky-pull-request-comment@v2
        with:
          path: coverage/SummaryGithub.md

yaml

name: Coverage

on:
  pull_request:
    branches: [main, dev]

jobs:
  coverage:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '9.0.x'

      - name: Restore tools
        run: dotnet tool restore

      - name: Run tests with coverage
        run: |
          dotnet test \
            --settings coverage.runsettings \
            --collect:"XPlat Code Coverage" \
            --results-directory ./TestResults

      - name: Generate report
        run: |
          dotnet reportgenerator \
            -reports:"TestResults/**/coverage.opencover.xml" \
            -targetdir:"coverage" \
            -reporttypes:"Html;MarkdownSummaryGithub;Cobertura"

      - name: Upload coverage report
        uses: actions/upload-artifact@v4
        with:
          name: coverage-report
          path: coverage/

      - name: Add coverage to PR
        uses: marocchino/sticky-pull-request-comment@v2
        with:
          path: coverage/SummaryGithub.md

Azure Pipelines

yaml

- task: DotNetCoreCLI@2
  displayName: 'Run tests with coverage'
  inputs:
    command: 'test'
    arguments: '--settings coverage.runsettings --collect:"XPlat Code Coverage" --results-directory $(Build.SourcesDirectory)/TestResults'

- task: DotNetCoreCLI@2
  displayName: 'Generate coverage report'
  inputs:
    command: 'custom'
    custom: 'reportgenerator'
    arguments: '-reports:"$(Build.SourcesDirectory)/TestResults/**/coverage.opencover.xml" -targetdir:"$(Build.SourcesDirectory)/coverage" -reporttypes:"HtmlInline_AzurePipelines;Cobertura"'

- task: PublishCodeCoverageResults@2
  displayName: 'Publish coverage'
  inputs:
    codeCoverageTool: 'Cobertura'
    summaryFileLocation: '$(Build.SourcesDirectory)/coverage/Cobertura.xml'

yaml

- task: DotNetCoreCLI@2
  displayName: 'Run tests with coverage'
  inputs:
    command: 'test'
    arguments: '--settings coverage.runsettings --collect:"XPlat Code Coverage" --results-directory $(Build.SourcesDirectory)/TestResults'

- task: DotNetCoreCLI@2
  displayName: 'Generate coverage report'
  inputs:
    command: 'custom'
    custom: 'reportgenerator'
    arguments: '-reports:"$(Build.SourcesDirectory)/TestResults/**/coverage.opencover.xml" -targetdir:"$(Build.SourcesDirectory)/coverage" -reporttypes:"HtmlInline_AzurePipelines;Cobertura"'

- task: PublishCodeCoverageResults@2
  displayName: 'Publish coverage'
  inputs:
    codeCoverageTool: 'Cobertura'
    summaryFileLocation: '$(Build.SourcesDirectory)/coverage/Cobertura.xml'

Quick Reference

快速参考

One-Liner Commands

一键命令

bash

undefined

bash

undefined

Full analysis workflow

完整分析流程

rm -rf coverage/ TestResults/ &&
dotnet test --settings coverage.runsettings
--collect:"XPlat Code Coverage"
--results-directory ./TestResults &&
dotnet reportgenerator
-reports:"TestResults/**/coverage.opencover.xml"
-targetdir:"coverage"
-reporttypes:"Html;TextSummary"

View summary

查看摘要

cat coverage/Summary.txt

Open HTML report (Linux)

打开HTML报告（Linux）

xdg-open coverage/index.html

Open HTML report (macOS)

打开HTML报告（macOS）

open coverage/index.html

Open HTML report (Windows)

打开HTML报告（Windows）

start coverage/index.html

undefined

start coverage/index.html

undefined

Project Standards

项目标准

Metric	New Code	Legacy Code
Line Coverage	80%+	60%+ (improve gradually)
Branch Coverage	60%+	40%+ (improve gradually)
Maximum CRAP	30	Document exceptions
High-risk methods	Must have tests	Add tests before modifying

指标	新代码	遗留代码
行覆盖率	80%+	60%+（逐步提升）
分支覆盖率	60%+	40%+（逐步提升）
最高CRAP分数	30	记录例外情况
高风险方法	必须有测试	修改前先补充测试

What Gets Excluded

排除内容说明

The recommended

coverage.runsettings

excludes:

Pattern	Reason
`[.Tests]`	Test assemblies aren't production code
`[.Benchmark]`	Benchmark projects
`[.Migrations]`	Database migrations (generated)
`GeneratedCodeAttribute`	Source generators
`CompilerGeneratedAttribute`	Compiler-generated code
`ExcludeFromCodeCoverageAttribute`	Explicit developer opt-out
`.g.cs` , `.designer.cs`	Generated files
`*.razor.g.cs`	Blazor component generated code
`*.razor.css.g.cs`	Blazor CSS isolation generated code
`/Migrations//*`	EF Core migrations (auto-generated)
`SkipAutoProps`	Auto-properties (trivial branches)

推荐的

coverage.runsettings

会排除以下内容：

模式	原因
`[.Tests]`	测试程序集不属于生产代码
`[.Benchmark]`	基准测试项目
`[.Migrations]`	数据库迁移文件（自动生成）
`GeneratedCodeAttribute`	源生成器生成的代码
`CompilerGeneratedAttribute`	编译器生成的代码
`ExcludeFromCodeCoverageAttribute`	开发者显式标记排除的代码
`.g.cs` , `.designer.cs`	自动生成的文件
`*.razor.g.cs`	Blazor组件生成的代码
`*.razor.css.g.cs`	Blazor CSS隔离生成的代码
`/Migrations//*`	EF Core迁移文件（自动生成）
`SkipAutoProps`	自动属性（无意义的分支）

When to Update Thresholds

何时更新阈值

Lower thresholds temporarily for:

Legacy codebases being modernized (document in README)
Generated code that can't be modified
Third-party wrapper code

Never lower thresholds for:

"It's too hard to test" - refactor instead
"We'll add tests later" - add them now
New features - should meet standards from the start

可临时降低阈值的场景：

正在现代化改造的遗留代码库（需在README中说明）
无法修改的生成代码
第三方包装器代码

绝对不能降低阈值的场景：

"测试难度太大" - 应优先重构
"以后再补测试" - 现在就添加
新功能 - 从一开始就需符合标准

Additional Resources

额外资源

Coverlet Documentation: https://github.com/coverlet-coverage/coverlet
ReportGenerator: https://github.com/danielpalme/ReportGenerator
CRAP Score Original Paper: http://www.artima.com/weblogs/viewpost.jsp?thread=215899

Coverlet文档: https://github.com/coverlet-coverage/coverlet
ReportGenerator: https://github.com/danielpalme/ReportGenerator
CRAP分数原始论文: http://www.artima.com/weblogs/viewpost.jsp?thread=215899

crap-analysis

Original

Translation

CRAP Score Analysis

CRAP分数分析

When to Use This Skill

何时使用该技能

What is CRAP?

什么是CRAP？

Why CRAP Matters

CRAP的重要性

CRAP Score Examples

CRAP分数示例

Coverage Collection Setup

覆盖率收集配置

coverage.runsettings

coverage.runsettings

Key Configuration Options

关键配置选项

ReportGenerator Installation

ReportGenerator安装

Add to .config/dotnet-tools.json

添加到.config/dotnet-tools.json

Or Install Globally

或全局安装

Collecting Coverage

收集覆盖率数据

Run Tests with Coverage Collection

运行测试并收集覆盖率

Clean previous results

清理之前的结果

Run unit tests with coverage

运行单元测试并收集覆盖率

Run integration tests (optional, adds to coverage)

运行集成测试（可选，会增加覆盖率数据）

Generate HTML Report

生成HTML报告

Report Types

报告类型

Reading the Report

报告解读

Risk Hotspots Section

风险热点部分

Interpreting Results

结果解读示例

Coverage Thresholds

覆盖率阈值

Recommended Standards

推荐标准

Configuring Thresholds

配置阈值

CI/CD Integration

CI/CD集成

GitHub Actions

GitHub Actions

Azure Pipelines

Azure Pipelines

Quick Reference

快速参考

One-Liner Commands

一键命令

Full analysis workflow

完整分析流程

View summary

查看摘要

Open HTML report (Linux)

打开HTML报告（Linux）

Open HTML report (macOS)

打开HTML报告（macOS）

Open HTML report (Windows)

打开HTML报告（Windows）

Project Standards

项目标准

What Gets Excluded

排除内容说明

When to Update Thresholds

何时更新阈值

Additional Resources

额外资源