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Generating Test data


You have seen that over and over: Test1, qwertyyui, asdfgh as data entered in development to test an application. Short of borrowing a copy of production data, having useful test data is a pain in the neck. For my currently limited exposure to development (after all I work as pre Sales engineer) I use a Java class that helps me to generate random result from a set of selection values. To make this work I used the following libraries:
  • JodaTime: takes the headache out of date calculation
  • gson: save and load JSON, in this case the random data
  • Lorem Ipsum: generate blocks of text that look good
  • Here you go:
    package com.notessensei.randomdata ;

    import java.io.InputStream ;
    import java.io.InputStreamReader ;
    import java.io.OutputStream ;
    import java.io.PrintWriter ;
    import java.util.Date ;
    import java.util.HashMap ;
    import java.util.List ;
    import java.util.Map ;
    import java.util.Random ;

    import org.joda.time.DateTime ;

    import com.google.gson.Gson ;

    import de.svenjacobs.loremipsum.LoremIpsum ;

    /**
     * Source of random data to generate test data for anything before use you need
     * either load lists of your data using addRandomStringSource or load a JSON
     * file from a previous run using loadDataFromJson
     *
     * @author NotesSensei
     *
     */

    public class RandomLoader {

        /*
         * How often should the random generator try for getRandomString with
         * exclusion before it gives up
         */

        public static final int             MAX_RANDOM_TRIES    = 100 ;
        private Map < String, List < String >>   randomStrings ;
        private Random                      randomGenerator ;

        /**
         * Initialize all things random
         */

        public RandomLoader ( ) {
            this. randomStrings = new HashMap < String, List < String >> ( ) ;
            this. randomGenerator = new Random ( new Date ( ). getTime ( ) ) ;
        }

        /**
         * Adds or ammends a collection of values to draw from
         */

        public void addRandomStringSource ( String sourceName, List < String > sourceMembers ) {
            if ( ! this. randomStrings. containsKey (sourceName ) ) {
                this. randomStrings. put (sourceName, sourceMembers ) ;
            } else {
                // We have a list of this name, so we add the values
                List < String > existingList = this. randomStrings. get (sourceName ) ;
                for ( String newMember : sourceMembers ) {
                    existingList. add (newMember ) ;
                }
            }
        }

        /**
         * Get rid of a list we don't need anymore
         *
         * @param sourceName
         */

        public void dropRandomStringSource ( String sourceName ) {
            if ( this. randomStrings. containsKey (sourceName ) ) {
                this. randomStrings. remove (sourceName ) ;
            }
        }

        /**
         * Gets a random value from a predefined list
         */

        public String getRandomString ( String sourceName ) {
            if ( this. randomStrings. containsValue (sourceName ) ) {
                List < String > sourceCollection = this. randomStrings. get (sourceName ) ;
                int whichValue = this. randomGenerator. nextInt (sourceCollection. size ( ) ) ;
                return sourceCollection. get (whichValue ) ;
            }
            // If we don't have that list we return the requested list name
            return sourceName ;
        }

        /**
         * Get a random String, but not the value specified Good for populating
         * travel to (exclude the from) or from/to message pairs etc
         *
         * @param sourceName
         *            from which list
         * @param excludedResult
         *            what not to return
         * @return
         */

        public String getRandomStringButNot ( String sourceName, String excludedResult ) {
            String result = null ;
            for ( int i = 0 ; i < MAX_RANDOM_TRIES ; i++ ) {
                result = this. getRandomString (sourceName ) ;
                if ( !result. equals (excludedResult ) ) {
                    break ;
                }
            }
            return result ;
        }

        /**
         * For populating whole paragraphs of random text LoremIpsum Style
         */

        public String getRandomParagraph ( int numberOfWords ) {
            LoremIpsum li = new LoremIpsum ( ) ;
            return li. getWords (numberOfWords ) ;
        }

        /**
         * Get a date in the future
         */

        public Date getFutureDate ( Date startDate, int maxDaysDistance ) {
            int actualDayDistance = this. randomGenerator. nextInt (maxDaysDistance + 1 ) ;
            DateTime jdt = new org. joda. time. DateTime (startDate ) ;
            DateTime jodaResult = jdt. plusDays (actualDayDistance ) ;
            return jodaResult. toDate ( ) ;
        }

        /**
         * Get a date in the past, good for approval simulation
         */

        public Date getPastDate ( Date startDate, int maxDaysDistance ) {
            int actualDayDistance = this. randomGenerator. nextInt (maxDaysDistance + 1 ) ;
            DateTime jdt = new org. joda. time. DateTime (startDate ) ;
            DateTime jodaResult = jdt. minusDays (actualDayDistance ) ;
            return jodaResult. toDate ( ) ;
        }

        /**
         * Lots of applications are about $$ approvals, so we need a generator
         */

        public float getRandomAmount ( float minimum, float maximum ) {
            // between 0.0 and 1.0F
            float seedValue = this. randomGenerator. nextFloat ( ) ;
            return (minimum + ( (maximum - minimum ) * seedValue ) ) ;
        }

        /**
         * Save the random strings to a JSON file for reuse
         */

        public void saveDatatoJson ( OutputStream out ) {
            Gson gson = new Gson ( ) ;
            PrintWriter writer = new PrintWriter (out ) ;
            gson. toJson ( this, writer ) ;
        }

        /**
         * Load a saved JSON file to populate the random strings
         */

        public static RandomLoader loadDataFromJson ( InputStream in ) {
            InputStreamReader reader = new InputStreamReader (in ) ;
            Gson gson = new Gson ( ) ;
            RandomLoader result = gson. fromJson (reader, RandomLoader. class ) ;
            return result ;
        }
    }
    As usual YMMV

Posted by on 18 January 2013 | Comments (0) | categories: Software

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