среда, 18 марта 2015 г.

Containers 11. A little about using DUnit

Original in Russian: http://18delphi.blogspot.ru/2013/03/dunit_29.html

About containers. Table of contents

Here we talked about patterns and mixins:
http://18delphi.blogspot.com/2015/02/containers-10-about-patterns-and-mixins.html

Now I’ll tell about the simplest use of DUnit framework.

The reasons WHY we need tests are given briefly here - http://18delphi.blogspot.com/2013/03/blog-post.html .

I think, in future I’ll give “real-world” examples.

Meanwhile, let’s just consider the technique by abstract example.

I will base on classes we’ve got in the previous example.

As usual, we’ll start with the diagram:


SandBox.dpr:

program SandBoxTest;
 
uses
  TestFrameWork
  GUITestRunner,
  IntStack,
  IntStackTest,
  StringStack,
  StringStackTest;
 
 
begin
 GUITestRunner.RunRegisteredTests;
end.

IntStackTest.pas:

unit IntStackTest;
 
interface
 
uses
  TestFrameWork
 
  ;
 
type
 TIntStackTest = {final} class(TTestCase)
 published
 // published methods
   procedure DoIt;
 end;//TIntStackTest
 
implementation
 
uses
  IntStack,
  SysUtils
  ;
 
// start class TIntStackTest
 
procedure TIntStackTest.DoIt;
const
 cEtalons : array [0..3] of integer = (10, 20, 3, 5);
var
 l_S : TIntStack;
 l_I : Integer;
begin
 l_S := TIntStack.Create;
 try
  for l_I := Low(cEtalons) to High(cEtalons) do
   l_S.Push(cEtalons[l_I]);
  for l_I := High(cEtalons) downto Low(cEtalons) do
   Check(l_S.Pop = cEtalons[l_I]);
 finally
  FreeAndNil(l_S);
 end;//try..finally
end;//TIntStackTest.DoIt
 
initialization
 TestFramework.RegisterTest(TIntStackTest.Suite);
 
end.

StringStackTest.pas:

unit StringStackTest;
 
interface
 
uses
  TestFrameWork
  ;
 
type
 TStringStackTest = class(TTestCase)
 published
 // published methods
   procedure DoIt;
 end;//TStringStackTest
 
implementation
 
uses
  StringStack,
  SysUtils
  ;
 
procedure TStringStackTest.DoIt;
const
 cEtalons : array [0..5] of String = ('The ', 'cat ', 'sat ', 'on ', 'the ','mat'); .

var
 l_S : TStringStack;
 l_I : Integer;
begin
 l_S := TStringStack.Create;
 try
  for l_I := Low(cEtalons) to High(cEtalons) do
   l_S.Push(cEtalons[l_I]);
  for l_I := High(cEtalons) downto Low(cEtalons) do
   Check(l_S.Pop = cEtalons[l_I]);
 finally
  FreeAndNil(l_S);
 end;//try..finally
end;//TStringStackTest.DoIt
 
 
initialization
 TestFramework.RegisterTest(TStringStackTest.Suite);
 
end.

-- we’ve got  tests of our classes’ workability :-)

As for me, it is cool. Especially if you run tests EVERY day :-) If we run them every day, we find out on-the-fly what is broken.

Don’t you dare say “it is VERY simple” :-) The devil is always in detail.

I’d try to give more complex examples “taken from life” further.

The main thing is that tests are a very simple way of debugging for many designed classes. Testing eliminates the need for developing a full-scale application wasting 10 minutes for compilation, for deploying database server and so on. One simply thinks up data out of his own head, writes a test and that’s it – he can debug this particular class.

It’s clear that you base on NAMELY THESE data. But nothing prevents us from gradual supplementing tests base and the base of “data from our own head”.

Later I’ll write about how I use mocks basing on etalon files.

Meanwhile read about the idea here:
https://en.wikipedia.org/wiki/Mock_object

If you ask to “show forms testing and GUI”, my answer will be “I’ll certainly show. I’ve got a wealth of experience”.

So far, concentrate on the fact that you should not be afraid to “touch” forms because they “stick out” for user. In contrast, be afraid to deal with base classes, especially if a few tens of different forms use them. Especially if they are written by “a guy who quit the job five years ago”. Especially if you don’t have tests. The more “base character” the class has and the more faults is found, the more tests will be written for it. One day. If you follow my recommendations. It will also become more stable.

Try it. May be you will like it.

The next series is here: http://18delphi.blogspot.com/2015/03/dunit-patterns-and-tests.html


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