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Codequalität messen EnterJS, 01. Juli 2014

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Andy Grunwald • Software Engineer bei @trivago
 • Open Source
 • @andygrunwald
 • @PHPUGDus
 • andygrunwald

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Code | qualität | messen

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–Helmut Balzert „Unter Softwarequalität versteht man die Gesamtheit der Merkmale … eines Softwareprodukts, …, festgelegte oder vorausgesetzte Erfordernisse zu erfüllen.“

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(Software)-Metriken

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Frontend Backend

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Frontend HTTP Requests Navigation Timing DOM Elemente Browser Repaints … Backend

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Frontend HTTP Requests Navigation Timing DOM Elemente Browser Repaints … Backend Request-Zeit Cache-Miss / -Hits Ressource-Zeit Business-Logik …

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Frontend HTTP Requests Navigation Timing DOM Elemente Browser Repaints … Backend Request-Zeit Cache-Miss / -Hits Ressource-Zeit Business-Logik … Source Code

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Source Code

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Source Code Functions count Nested depth Halstead Maintainability index LOC Parameter count Cyclomatic Complexity nPath Lint errors CLOC LLOC Your metric here

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Source Code Functions count Nested depth Halstead Maintainability index LOC Parameter count Cyclomatic Complexity nPath Lint errors CLOC LLOC Your metric here

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// Is a given array, string, … // An "empty" object has … _.isEmpty = function(obj) { if (obj == null) { return true; } ! if (_.isArray(obj)) { return obj.length === 0; } ! for (var key in obj) { if (_.has(obj, key)) { return false; } } ! return true; }; _.isEmpty(e);

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// Is a given array, string, … // An "empty" object has … _.isEmpty = function(obj) { if (obj == null) { return true; } ! if (_.isArray(obj)) { return obj.length === 0; } ! for (var key in obj) { if (_.has(obj, key)) { return false; } } ! return true; }; _.isEmpty(e); • LOC: 19

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// Is a given array, string, … // An "empty" object has … _.isEmpty = function(obj) { if (obj == null) { return true; } ! if (_.isArray(obj)) { return obj.length === 0; } ! for (var key in obj) { if (_.has(obj, key)) { return false; } } ! return true; }; _.isEmpty(e); • LOC: 19
 • CLOC: 2

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// Is a given array, string, … // An "empty" object has … _.isEmpty = function(obj) { if (obj == null) { return true; } ! if (_.isArray(obj)) { return obj.length === 0; } ! for (var key in obj) { if (_.has(obj, key)) { return false; } } ! return true; }; _.isEmpty(e); • LOC: 19
 • CLOC: 2
 • NCLOC: 17

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_.isEmpty(e); • LOC: 19
 • CLOC: 2
 • NCLOC: 17
 • LLOC: 9 // Is a given array, string, … // An "empty" object has … _.isEmpty = function(obj) { if (obj == null) { return true; } ! if (_.isArray(obj)) { return obj.length === 0; } ! for (var key in obj) { if (_.has(obj, key)) { return false; } } ! return true; };

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Source Code Functions count Nested depth Halstead Maintainability index LOC Parameter count Cyclomatic Complexity nPath Lint errors CLOC LLOC Your metric here

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Source Code Functions count Nested depth Halstead Maintainability index LOC Parameter count Cyclomatic Complexity nPath Lint errors CLOC LLOC Your metric here

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Cyclomatic Complexity / McCabe Anzahl von Entscheidungspunkten innerhalb einer Funktion (if, switch, for, while, …)

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } } Cyclomatic Complexity: 4

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nPath Complexity Anzahl einzigartiger Ausführungspfade innerhalb einer Funktion

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } }

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function nestedFunction(x, y, z) { if (x > 0) { if (y > 0) { if (z > 0) { console.log(z); } } } } nPath Complexity: 4

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Cyclomatic Complexity === nPath?

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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Cyclomatic Complexity: 4 function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } }

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function nPath(x, y, z) { if (x > 0) { console.log(x); } ! if (y > 0) { console.log(y); } ! if (z > 0) { console.log(z); } } nPath Complexity: 8

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escomplex complexity-report plato Esprima yardstick jsmeter

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escomplex complexity-report plato Esprima yardstick jsmeter

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ScanJS JSHint jsprime DoctorJs JSWhiz WALA

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+

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Sprach-Features

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function foo() { var a = [0, 1, 2, 3, 4]; for (index = 0; index < a.length; ++index) { console.log(a[index]); } }

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function foo() { for (key in [0, 1, 2, 3, 4]) { console.log(key); } } function foo() { var a = [0, 1, 2, 3, 4]; for (index = 0; index < a.length; ++index) { console.log(a[index]); } }

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function foo() { for (key in [0, 1, 2, 3, 4]) { console.log(key); } } function foo() { [0, 1, 2, 3, 4].forEach(function (i) { console.log(i); }); } function foo() { var a = [0, 1, 2, 3, 4]; for (index = 0; index < a.length; ++index) { console.log(a[index]); } }

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JavaScript ist eine dynamische Sprache

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var a = 'if(arguments[0] > 0) ' + 'console.log(arguments);'; new Function(a)(5);

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var a = '(function() {' + 'if(arguments[0] > 0) ' + 'console.log(arguments);' + '})(6)'; eval(a); var a = 'if(arguments[0] > 0) ' + 'console.log(arguments);'; new Function(a)(5);

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Referenzwerte / Schwellenwerte + Kontext

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Referenzwerte / Schwellenwerte Niedrig Normal Hoch Sehr hoch Cyclomatic Complexity 1-4 5-7 8-10 >= 11 nPath / / / >= 200

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Java (45 Projekte) Metrik Niedrig Normal Hoch Sehr hoch CYCLO/LOC 0.16 0.20 0.24 0.36 LOC/Methode 7 10 13 19.5 NOM/Class 4 7 10 15

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Java (45 Projekte) Metrik Niedrig Normal Hoch Sehr hoch CYCLO/LOC 0.16 0.20 0.24 0.36 LOC/Methode 7 10 13 19.5 NOM/Class 4 7 10 15 C++ (37 Projekte) Metrik Niedrig Normal Hoch Sehr hoch CYCLO/LOC 0.20 0.25 0.30 0.45 LOC/Methode 5 10 16 24 NOM/Class 4 9 15 22.5

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Metriken

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Source Code

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Source Code Functions count Nested depth Halstead Maintainability index LOC Parameter count Cyclomatic Complexity nPath Lint errors CLOC LLOC Your metric here

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Verwendete Bilder • „Ruler“ by Scott Akerman: https://www.flickr.com/ photos/sterlic/4299631538/ • „the JavaScript Code“ by Dmitry Baranovskiy: https:// www.flickr.com/photos/dmitry-baranovskiy/2378867408 • „Ignition“ by Zach Dischner: https://www.flickr.com/ photos/zachd1_618/3489625168 • „Tools IMG_0171“ by OZinOH: https://www.flickr.com/ photos/75905404@N00/7126146307

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Verwendete Bilder • „Danger & Skull, Legoland“ by bixentro: https:// www.flickr.com/photos/bixentro/338433029 • „Baby“ by The Noun Project: http://thenounproject.com/ term/baby/47/ • „Man“ by The Noun Project: http://thenounproject.com/ term/man/2/ • „Sasquatch“ by Mike Wirth: http://thenounproject.com/ term/sasquatch/2680/

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Verwendete Bilder • „Waking Up In Abbeyford Woods“ by Miles Wolstenholme: https://www.flickr.com/photos/ oaktorphotography/14444806464 • „Danke 102/365“ by Dennis Skley: https:// www.flickr.com/photos/dskley/13796815083/ • „Questions“ by Oberazzi: https://www.flickr.com/photos/ oberazzi/318947873/in/photostream/

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Zitate und Tabellen • Helmut Balzert: Lehrbuch der Softwaretechnik. Band 2: Softwaremanagement, Software-Qualitätssicherung, Unternehmensmodellierung, Spektrum Akademischer Verlag, Heidelberg 1998, ISBN 3-8274-0065-1, S. 257 • Michele Lanza, Radu Marinescu: Object-Oriented Metrics in Practice: Using Software Metrics to Characterize, Evaluate, and Improve the Design of Object-Oriented Systems, Springer 2006, ISBN 3540244298