java - JUnit testing for IO -

i new here , new junit testing. have class 2 methods , want write unit tests it. not sure how start read basic tutorials not able start how. can of provide me basic skeleton start with.

my class

 public class createcsv  {     mywriter csvoutput = null;     public void createsortedset ( final hashmap< string, signal > map, final long totalsize, final long totalsizewithheader, file file )   {     arraylist< signal > messages = new arraylist< signal >();     try     {         messages.addall( map.values() );         map.clear();         ( signal signal : messages )         {             signal.setbandwidth( ( signal.getsize() / ( float ) totalsize ) * 100 );             signal.setbandwidthwithheader( ( signal.getsizewithheader() / ( float ) totalsizewithheader ) * 100 );         }         collections.sort( messages, new signalcomparator() );     }     catch ( exception e )     {         logger.error( "error in creating messages data", e );     }     createcsv( messages, file ); }  public void createcsv ( final arraylist< signal > messages, file file ) {     try     {         // use filewriter constructor specifies open appending         csvoutput = new mywriter( new filewriter( file, false ), ',' );          // create header csv         csvoutput.writerecord( "message source" );         csvoutput.writerecord( "message name" );         csvoutput.writerecord( "component" );         csvoutput.writerecord( "occurance" );         csvoutput.writerecord( "message payload header" );         csvoutput.writerecord( "bandwidth(with header %)" );         csvoutput.writerecord( "message payload" );         csvoutput.writerecord( "bandwidth(%)" );         csvoutput.endofrecord();          ( signal signal : messages )         {             csvoutput.writerecord( signal.getsource() );             csvoutput.writerecord( signal.getname() );             csvoutput.writerecord( signal.getcomponent() );             csvoutput.writerecord( integer.tostring( signal.getoccurance() ) );             csvoutput.writerecord( integer.tostring( signal                 .getsizewithheader() ) );             csvoutput.writerecord( float.tostring( signal                 .getbandwidthwithheader() ) );             csvoutput.writerecord( integer.tostring( signal.getsize() ) );             csvoutput.writerecord( float.tostring( signal.getbandwidth() ) );             csvoutput.endofrecord();         }     }     catch ( ioexception e )     {         logger.error( "error in writing csv file messages", e );     }         {         try         {             if ( csvoutput != null )             {                 csvoutput.flush();                 csvoutput.close();             }             messages.clear();         }         catch ( ioexception ex )         {             ex.printstacktrace();         }     }  } } 

the signal class

 public class signal {  private string source;  private string name;  private string component;  private int occurance;  private int size;  private int sizewithheader;  private float bandwidth;  private float bandwidthwithheader;  /**  * @param source  */ public void setsource ( string source ) {     this.source = source; }  /**  * @param name  */ public void setname ( string name ) {     this.name = name; }  /**  * @param component  */ public void setcomponent ( string component ) {     this.component = component; }  /**  * @param occurance  */ public void setoccurance ( int occurance ) {     this.occurance = occurance; }  /**  * @param size  */ public void setsize ( int size ) {     this.size = size; }  /**  * @param bandwidth  */ public void setbandwidth ( float bandwidth ) {     this.bandwidth = bandwidth; }  /**  * @param sizewithheader  */ public void setsizewithheader ( int sizewithheader ) {     this.sizewithheader = sizewithheader; }  /**  * @param bandwidthwithheader  */ public void setbandwidthwithheader ( float bandwidthwithheader ) {     this.bandwidthwithheader = bandwidthwithheader; }  /**  * @return string  */ public string getsource () {     return this.source; }  /**  * @return string  */ public string getname () {     return this.name; }  /**  * @return string  */ public string getcomponent () {     return this.component; }  /**  * @return int  */ public int getoccurance () {     return this.occurance; }  /**  * @return int  */ public int getsize () {     return this.size; }  /**  * @return float  */ public float getbandwidth () {     return this.bandwidth; }  /**  * @return int  */ public int getsizewithheader () {     return this.sizewithheader; }  /**  * @return float  */ public float getbandwidthwithheader () {     return this.bandwidthwithheader; } }  

just give head start

create test class looks this

import junit.framework.testcase;  public class createcsvtest extends testcase {      createcsv csv = new createcsv();      public void testcreatecsv() {         csv.createcsv("pass arraylist of type signal", "pass file");         assertequals("add asserts here", "add asserts here");     }  }