Introduction to Software Engineering: Tools and Environments Session 6 Oded Lachish Room: Mal 405 Visiting Hours: Wednesday 17:00 to 20:00 Email: [email protected] Module URL: http://www.dcs.bbk.ac.uk/~oded/Tools2012-2013/Web/Tools2012-2013.html 1 y Clone project from git://github.com/odedlac/Verification.git 2 Until now • High level overview of the SDLC • Welcome to Eclipse –Refactor, Source • Version control –git • Unit testing – Junit • Mocking –mockito Hopefully by now we know how to mock software. But what if there is a bug? “println” –we don’t want to touch the code 3 Eclipse has a plug‐ins • Debugger • Code coverage • Static code analysis 4 Debugging 5 Clone project from git://github.com/odedlac/Verification.git 6 Debugger Press F11 7 Debugger View 8 Set a breakpoint • Pick line • Add breakpoint 9 Notice the hotkeys Breakpoint • Right click menu 10 Debug Local variable values Stopped at breakpoint 11 Debug Local variable values Stopped at breakpoint 12 Debug Local variable values Stopped at breakpoint 13 After breakpoint reached –execution suspended Two options Before resume After resume 14 Step into (the method) Then step return, what does step over do? 15 What else can we do? Pick code and right mouse click 16 Options • All instances ‐ list of all java object of selected type • Instance count – number of instances of selected type • Force return –forces a return with a specified value • Watch –shows contents on “expressions “ • Inspect –shows contents • Display –shows value pop‐up dialog • Run to line –run until the line selected (when we don’t wont a breakpoint) 17 To do now • Change code so that you can easily see how things behave. • Try to find bug 18 Code Coverage ecorbetura http://ecobertura.johoop.de/update/ 19 Code Coverage How do you know you have tested enough. (At least in theory it seems you never know) However one popular metric is code coverage. The idea is to check for example • All lines of code were executed • All conditions in the code evaluated to every possible value Naturally this process is automated. 20 ecorbetura • Open source code coverage tool • Reports which lines are covered • Reports which branches were covered • Reports line coverage percentage • Reports branch coverage percentage 21 Tell Eclipse to use coverage 22 After we ran test Green is covered Red not covered 23 Coverage report Go here 24 Coverage report Choose this 25 Coverage report 26 Now Get all These Colours Out of My Code Have you tried turning it of and on again? 27 Static Code Analysis FindBugs 28 FindBugs http://ecobertura.johoop.de/update/ 29 FindBugs (http://findbugs.cs.umd.edu/eclipse/) What: Static code analyzer (does not execute code) Why: find java “bugs” and “bad coding” examples: • Comparing objects instead of using equals • null pointers. String name; if (name == null || name.length() == 0) return; In this case “name” may never be null. 30 FindBugs 31 FindBugs results 32 PMD http://pmd.sourceforge.net/eclipse 33 PMD (http://pmd.sourceforge.net/eclipse) What: Static code analyzer (does not execute code) Why: find java “bugs” and “bad coding” examples: • Possible bugs ‐ empty try/catch/finally/switch statements • Dead code ‐ unused local variables, parameters and private methods • Suboptimal code ‐ wasteful String usage • Overcomplicated expressions ‐ unnecessary if statements, for loops that could be while loops • Duplicate code ‐ copied/pasted code means copied/pasted bugs 34 PMD 35 PMD challenge Change your code so that PMD shouts 36 checkStyle http://eclipse-cs.sf.net/update/ 37 checkstyle What: Static code analyzer (does not execute code) Why: make sure that the style of code adheres to standards: Annotations Block Checks Class Design Coding Duplicate Code Headers Imports Javadoc Comments Metrics Miscellaneous Modifiers Naming Conventions Regexp Size Violations Whitespace 38 checkstyle What else? checkstyle can be extended The functionality of checkstyle is implements as checks. You need to know how to write checks to write new functionality. 39 checkStyle 40 checkstyle challenge Change your code so that checkstyle is happy 41.