= Unittests =

''Part of'' TutorialFundamentals

== Description ==

Unittests let you find the bugs before you even run the program.


== About unittests ==

According to this example, unittests may be run in the order they appear in the code. Since the Whatever class appears before the module unittests, these are run first. 

The -unittests flag has to be used to compile this program or else this code is ignored.
        

== Example ==

{{{
#!d
module unittests;

import std.stdio;

void main() {
    writefln("test");
    /* This assertion will fail. */
    assert(false);  

    /* 
        The line number (7) may be different, but this is the 
        error message which should appear...
        Error: AssertError Failure unittests(7)
    */
}

class Whatever {
   
    unittest {
        writefln("class Whatever UnitTest...");
        /* If the expession of an assert doesn't evaluate to true, an exception is thrown at run-time. */

        assert(true==1);
        assert(true);
        assert(false==false);
        assert(!false);
    }
}

unittest {
    writefln("module UnitTest...");
    assert(true==1);
    assert(true);
    assert(false==false);
}
}}}






== Example 2 ==

{{{
#!d
module unittests;

import std.stdio;

void main() {
  writefln( "Passes!");

  return;
}


class Factoid {
  int factorial() {
    int x = 1;
    int f;

    for( x = 0 ; x <= m_int; ++x) {
      if( x == 0) {
	f = 1;
      }
      else {
	f *= x;
      }
    }

    return f;
  }


  this(int x) {
    m_int = x;
  }

  private{
    int m_int;
  }

  unittest{
    Factoid f = new Factoid(3);

    assert( 6 == f.factorial());
  }
}
}}}