Got units? @ Osidays 2011 India 11-20-2011

Got units? Bengaluru, 20-22 November 2011

TDDBengaluru, 20-22 November 2011

REDadd a test, it wont pass Bengaluru, 20-22 November 2011

GREENimplement the necessary code to make the test pass Bengaluru, 20-22 November 2011

REFACTOR polish the code Bengaluru, 20-22 November 2011

TDD-ing Dijkstrasshortest path algorithm in PHP Bengaluru, 20-22 November 2011

Bengaluru, 20-22 November 2011

github.com/odino/osidays Bengaluru, 20-22 November 2011

git checkout $stepBengaluru, 20-22 November 2011

Step 0/1● create the directory structure● add Symfony2 classloader as submodule● init and update submodule● (optional) create an empty class Bengaluru, 20-22 November 2011

Step 2● write the test with the smallest amount of code you think its necessary Bengaluru, 20-22 November 2011

Step 3● add the Vertex class● add the Graph class● add an empty solve() method for the algorithm class Bengaluru, 20-22 November 2011

Step 4● implement the solve method Bengaluru, 20-22 November 2011

Step 5● added all the methods needed by the Dijkstra::solve()● need to implement Graph::calculatePotentials() Bengaluru, 20-22 November 2011

Step 6● a test is added for the Graph class Bengaluru, 20-22 November 2011

Step 7● calculatePotentials() is tested● half of our test-suite passes● switch back to the Dijkstras test Bengaluru, 20-22 November 2011

Step 8● minor tweaks to make all the tests pass Bengaluru, 20-22 November 2011

Step 9● potentials are assigned in the Graph class but they should belong to the algorithm, what about refactoring the code?● since we move the only tested method of Graph into Dijkstras class, we can delete the GraphTest Bengaluru, 20-22 November 2011

Step 10● since we like to be OO, we can connect vertices through objects, and not arrays anymore Bengaluru, 20-22 November 2011

Step 11● we now need to fix the code which uses vertices connections as arrays Bengaluru, 20-22 November 2011

Step 12● the library seems pretty complete● PHPDoc is added Bengaluru, 20-22 November 2011

Step 13● Oooops, we forgot to test a scenario: in Dijkstras algorithm we need vertices connected by positive distance● a test is added, verifying an exception is raised through annotations Bengaluru, 20-22 November 2011

Step 14● implementation Bengaluru, 20-22 November 2011

Step 15● enter Mocking objects Bengaluru, 20-22 November 2011

Step 16● Dijkstra::getGraph() seems to be useless so we probably dont need any Graph class Bengaluru, 20-22 November 2011

Step 17● removed Graph class Bengaluru, 20-22 November 2011

Step 18● some tests rely on it, so we need to eliminate old references to Graph Bengaluru, 20-22 November 2011

Step 19● enter Data Providers Bengaluru, 20-22 November 2011

Step 20● what about calculating the path between not-connected vertices? It should return null, so code is refactored Bengaluru, 20-22 November 2011

Step 21● Dijkstra::solve() seems to do too much things, so we split the method● first demand potentials calculation● second demand path finding● third demand raising the negative-potentials exception● enter phploc● enter code-coverage Bengaluru, 20-22 November 2011

Alessandro Nadalin Bengaluru, 20-22 November 2011

odino.orgBengaluru, 20-22 November 2011

Bengaluru, 20-22 November 2011

@_odino_ #osidaysBengaluru, 20-22 November 2011

REST in peace: tomorrow, 12.45 Bengaluru, 20-22 November 2011

Thank YOU! @_odino_ Bengaluru, 20-22 November 2011

Got units? @ Osidays 2011 India 11-20-2011

by Alessandro Nadalin

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Got units? @ Osidays 2011 India 11-20-2011 Presentation Transcript