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

My talk about quality metrics at NSSpain 2014

Transcript

1. Hello
2. Be the quality you want to see in the World
3. Code quality metrics
4. How many of you calculate code metrics in ObjC?
5. It's a long story
6. Introduction What are code metrics?
7. You get what you measure — Joshua Appelman
8. Code metrics are a set of software measures
9. Cool.
10. But.
11. " Why should I bother about that? "
12. Because you want: To understand which methods/classes should be reworked Your development team to identify potential risks To track progress during software development
13. And, ultimately, because you — your codebase
14. —
15. " When should I use that? "
16. 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
18. " When should I use that? " Practically everyday
19. Which code metrics?
20. # lines of code / # of files
21. 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") } } }
22. 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
23. Code coverage
24. Duplications (CPD)
25. Depth of inheritance
26. Class coupling
27. NCSS
28. HSLOCR
29. HSLOCR Holy Sh*t / Lines of Code Ratio
30. LASER
31. LASER LAser Shark Exposure Rate
33. —
34. How to generate code metrics?
35. PMD
36. 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
37. Clang Static Analyzer
38. 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
39. AppCode
40. 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
41. —
42. gcovr
43. 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
44. OCLint
45. OCLint Inspired by PMD and by the AppCode static analyzer Based on Clang Exports to the PMD file format
46. OCLint Detects: • Empty control flow statements • Unused code • Complicated code (high cyclomatic/NPath complexity, deep statements) • Redundant if statements • Long methods, long parameter list
47. OCLint Rules are extensible You can write your own
48. OCLint - Installing http://docs.oclint.org/en/dev/intro/installation.html Make the binary available from your path
49. Tools
50. SonarQube
51. 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
52. SonarQube - Installing $ brew install sonar $ brew install sonar-runner # Front end
53. SonarQube Runner
54. SonarQube Runner Is the frontend for executing sonar Reads a sonar-project.properties file in the project folder
55. SonarQube Objective-C plugin
56. SonarQube Objective-C plugin Developed by Octo Technologies, Paris github.com/octo-technology/sonar-objective-c Aggregates: • OCLint results • Test coverage (via Cobertura) • CPD
57. SonarQube Objective-C plugin - Installing build from sources: $ mvn install
58. " When should I use that? " Practically everyday
59. Automate!
60. Automate!!
61. Automate!!!
62. Automate!!!
63. A real life project 1. Jenkins 2. xcodebuild/xctool/xcpretty 3. OCLint 4. Run Tests 5. Run gcovr 6. Sonar
64. Warning: bash Proceed with caution
65. Let's dive in
66. 1. Jenkins Runs project jobs A job can consist in compilation, testing, analysis, deployment tasks Jobs can be parametrized
67. 2. xcodebuild/xctool/xcpretty $ /usr/bin/xcodebuild [params] > xcodebuild.log
68. 3. OCLint $ oclint-xcodebuild # Generates compile_commands.json $ oclint-json-compilation-database > -- -report-type pmd -o sonar-reports/oclint.xml
69. 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"
70. 5. Run gcovr $ ./scripts/gcovr -r . PATH/TO/DUCKING/DERIVEDDATA/ > --exclude .*Tests.* --xml > > "${PWD}/sonar-reports/coverage.xml"
71. 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
72. 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 $?
76. Final thoughts
77. 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
78. You get what you measure — Joshua Appelman
79. Share the results with your team Improve continuously
80. Be the quality you want to see in the World
81. —
82. Thank y—u!
83. Simone Civetta @viteinfinite