Be the Quality you Want to See in the World - Code Quality Metrics

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Hello

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Be the quality you want to see in the World

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Code quality metrics

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How many of you calculate code metrics in ObjC?

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It's a long story

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Introduction What are code metrics?

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You get what you measure — Joshua Appelman

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Code metrics are a set of software measures

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Cool.

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But.

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" Why should I bother about that? "

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Because you want: To understand which methods/classes should be reworked Your development team to identify potential risks To track progress during software development

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And, ultimately, because you — your codebase

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—

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" When should I use that? "

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Basically, when you Have a large codebase Work in heterogeneous teams Are writing an audit Want to get a rapid overview of an inherited codebase

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" When should I use that? " Practically everyday

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Which code metrics?

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# lines of code / # of files

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Cyclomatic complexity func example(a: Int, b: Int, c:Int, d:Int) { // 1 if a == b { // 2 println("Hello") } else if (c == d) { // 3 for index in 1...5 { // 4 println("Hello") } } else { // 5 switch c { case 1: // 6 println("Hello") case 2: // 7 println("Hello") default: // 8 println("Hello") } } }

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NPath complexity func example(a:Int, b:Int) { if a > 10 { println(1) } else { println(2) } if a > b { println(3) } else { println(4) } } // Result: 4

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Code coverage

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Duplications (CPD)

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Depth of inheritance

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Class coupling

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NCSS

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HSLOCR

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HSLOCR Holy Sh*t / Lines of Code Ratio

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LASER

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LASER LAser Shark Exposure Rate

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How to generate code metrics?

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PMD

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PMD Java static analyzer - a must-have of the Java developer Supports Java, JavaScript, XML Identiﬁes: • Unused variables • Empty catch blocks • Unnecessary object creation • Cyclomatic/NPath complexity

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Clang Static Analyzer

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Clang Static Analyzer Part of the Clang project Run as standalone or included via Xcode Analyzes the different execution paths (Abstract Syntax Tree) Detects wether some paths can lead to problems

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AppCode

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AppCode Performs checks for: • Clang analysis • Class errors (hidden scopes, missing implementations) • Data ﬂow analysis • Obsolete vs Modern syntax checking • String localisation control • Unavailable/deprecated APIs

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gcovr

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gcovr Generates code coverage reports from .gcda and .gcno ﬁles Exports to the Cobertura1 XML format .gcda and .gcno ﬁles are generated by setting • GCC_GENERATE_TEST_COVERAGE_FILES • GCC_INSTRUMENT_PROGRAM_FLOW_ARCS 1 - Cobertura: an open source tool for measuring Java code coverage

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OCLint

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OCLint Inspired by PMD and by the AppCode static analyzer Based on Clang Exports to the PMD ﬁle format

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OCLint Detects: • Empty control ﬂow statements • Unused code • Complicated code (high cyclomatic/NPath complexity, deep statements) • Redundant if statements • Long methods, long parameter list

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OCLint Rules are extensible You can write your own

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OCLint - Installing http://docs.oclint.org/en/dev/intro/installation.html Make the binary available from your path

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Tools

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SonarQube

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SonarQube A Web Application for Continuous Inspection of code quality Acts as an hub for code metrics Integrates with other tools such as PMD, Cobertura or OCLint

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SonarQube - Installing $ brew install sonar $ brew install sonar-runner # Front end

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SonarQube Runner

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SonarQube Runner Is the frontend for executing sonar Reads a sonar-project.properties ﬁle in the project folder

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SonarQube Objective-C plugin

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SonarQube Objective-C plugin Developed by Octo Technologies, Paris github.com/octo-technology/sonar-objective-c Aggregates: • OCLint results • Test coverage (via Cobertura) • CPD

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SonarQube Objective-C plugin - Installing build from sources: $ mvn install

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" When should I use that? " Practically everyday

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Automate!

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Automate!!

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Automate!!!

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Automate!!!

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A real life project 1. Jenkins 2. xcodebuild/xctool/xcpretty 3. OCLint 4. Run Tests 5. Run gcovr 6. Sonar

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Warning: bash Proceed with caution

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Let's dive in

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1. Jenkins Runs project jobs A job can consist in compilation, testing, analysis, deployment tasks Jobs can be parametrized

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2. xcodebuild/xctool/xcpretty $ /usr/bin/xcodebuild [params] > xcodebuild.log

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3. OCLint $ oclint-xcodebuild # Generates compile_commands.json $ oclint-json-compilation-database > -- -report-type pmd -o sonar-reports/oclint.xml

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4. Run tests $ GCC_GENERATE_TEST_COVERAGE_FILES=YES > GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES > /usr/bin/xcodebuild test | xcpretty -tc --report junit > --output "${PWD}/sonar-reports/TEST-report.xml"

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5. Run gcovr $ ./scripts/gcovr -r . PATH/TO/DUCKING/DERIVEDDATA/ > --exclude .*Tests.* --xml > > "${PWD}/sonar-reports/coverage.xml"

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6. Sonar-Runner - Property file sonar.projectKey=nsspaindemo sonar.projectName=NSSpainDemo sonar.language=objc sonar.projectDescription=NSSpainDemo sonar.sources=NSSpainDemo/ sonar.objectivec.project=NSSpainDemo.xcodeproj

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Putting it all together #!/bin/bash BUILD_CMD_SUFFIX="-project ${PROJECT_NAME}.xcodeproj -derivedDataPath ${PWD}/DerivedData -configuration Debug" \ # Clean the folders rm -rf ${PWD}/sonar-reports rm -rf ${PWD}/DerivedData mkdir ${PWD}/sonar-reports # Build /usr/bin/xcodebuild ${BUILD_CMD_SUFFIX} -scheme "${DEFAULT_SCHEME}" \ -sdk "${DEFAULT_SDK}" > xcodebuild.log # Generate compile commands /usr/local/bin/oclint-xcodebuild /usr/local/bin/oclint-json-compilation-database "${PWD}/${PROJECT_NAME}" \ -- -report-type pmd -o sonar-reports/oclint.xml # Run tests GCC_GENERATE_TEST_COVERAGE_FILES=YES \ GCC_INSTRUMENT_PROGRAM_FLOW_ARCS=YES \ /usr/bin/xcodebuild ${BUILD_CMD_SUFFIX} -scheme "${DEFAULT_SCHEME}" \ -sdk "${DEFAULT_SDK}" test | xcpretty -tc --report junit \ --output "${PWD}/sonar-reports/TEST-report.xml" # Generate coverage report ./scripts/gcovr -r . \ ${PWD}/DerivedData/Build/Intermediates/"${DEFAULT_SCHEME}".build/Debug-iphonesimulator/"${DEFAULT_TARGET}".build/Objects-normal/i386 \ --exclude .*Tests.* --xml > "${PWD}/sonar-reports/coverage.xml" # Send results to SonarQube /usr/local/bin/sonar-runner exit $?

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Final thoughts

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Final thoughts • Automate, automate, automate • Code metrics are not Gospel • Static analysis alone is not enough • Pick a range of complementary metrics • Be honest with yourself • Aim for all metrics rather than excelling in a single one