Approaches to Automatically Testing Visual Components

1
Approaches to Automatically Testing Visual
Components

• Richard B. Winston
• CPCUG Programmers SIG
• Nov. 1, 2006

2
Outline

• Review of DUnit
• Difficulties Using Dunit with Visual Components
• Simulating User Interaction in DUnit
• Comparing Appearances of Visual Components
• Limitations

3
Review of DUnit

• Testing Framework for Delphi
• Open Source http//dunit.sourceforge.net/
• Built-in support in BDS 2005 and 2006
• Works with Delphi gt 5

4
DUnit Example 1

• type
• // Test methods for class TRbwParser
• TestTRbwParser class(TTestCase)
• strict private
• FRbwParser TRbwParser
• public
• procedure SetUp override
• procedure TearDown override
• published
• procedure TestClearExpressions
• end

5
DUnit Example 2

• procedure TestTRbwParser.TestClearExpressions
• var
• Expression string
• begin
• if FRbwParser.ExpressionCount 0 then
• begin
• Expression '12'
• FRbwParser.Compile(Expression)
• end
• Check(FRbwParser.ExpressionCount gt 0, 'Error in
  counting expressions')
• FRbwParser.ClearExpressions
• Check(FRbwParser.ExpressionCount 0, 'Error in
  clearing expressions')
• end

6
DUnit in Action
7
Manually Testing User Interaction

• Manual
• Ask the user to do something
• Let the user decide if the results are correct
• Problems
• Slow
• Unreliable
• Discourages Testing

8
Automatically Test User Interaction

• Simulate Mouse and Keyboard Events
• Get Screen Captures of the Controls
• Compare the New Screen Captures to Old Ones
• Borlands private Zombie program does something
  similar. See http//www.stevetrefethen.com/files/
  index.html

9
Windows API for Simulating the Mouse and Keyboard

• Mouse_Event( MOUSEEVENTF_LEFTDOWN, 0, 0, 0, 0)
• Keybd_Event(key, MapvirtualKey(key, 0), flag, 0)

10
Simulate Mouse and Keyboard

• // move the mouse to cell 0,1
• APoint CellCenter(frmGridTest.TestGrid,
  0,1)
• MoveMouseToPosition(APoint)
• // double click on the cell to start
  editing text.
• DoubleClick
• // enter some text.
• SimultateText('abcd efgh ijkl')

11
CellCenter

• function CellCenter(Const Grid TCustomDrawGrid
  Const ACol, ARow integer) TPoint
• var
• ARect TRect
• begin
• ARect Grid.CellRect(ACol,ARow)
• result.X (ARect.Left ARect.Right) div 2
• result.Y (ARect.Top ARect.Bottom) div 2
• result Grid.ClientToScreen(result)
• end

12
MoveMouseToPosition

• Procedure MoveMouseToPosition(Position TPoint)
• Begin
• Mouse.CursorPos Position
• Application.ProcessMessages
• end

13
MouseClick

• procedure MouseGoesDown
• begin
• Mouse_Event( MOUSEEVENTF_LEFTDOWN, 0, 0, 0,
  0)
• end
• procedure MouseGoesUp
• begin
• Mouse_Event( MOUSEEVENTF_LEFTUP, 0, 0, 0, 0)
• end

• procedure MouseClick
• begin
• MouseGoesDown
• MouseGoesUp
• end
• procedure DoubleClick
• begin
• MouseClick
• MouseClick
• end

14
DragMouse

• procedure DragMouse(Start, Stop TPoint)
• Const
• TenthSecond 100 // 100 milliseconds - 1/10
  second. This value works for me.
• begin
• MoveMouseToPosition(Start)
• MouseGoesDown
• try
• MoveMouseToPosition(Stop)
• // To generate a mouse move event, enough
  time must elapse.
• // Empirically 1/20'th of a second is enough.
• Sleep(TenthSecond)
• Application.ProcessMessages
• finally
• MouseGoesUp
• Application.ProcessMessages
• end
• end

15
SimultateText

• Procedure SimultateText(const AString string)
• var
• CharIndex integer
• AChar Char
• KeyCode TKeyCode
• Shift TShiftState
• begin
• for CharIndex 1 to Length(AString) do
• begin
• AChar AStringCharIndex
• KeyCode.LongKeyCode VkKeyScan(AChar)
• Shift

• if (KeyCode.Shift and 1) ltgt 0 then
• begin
• Include(Shift, ssShift)
• end
• if (KeyCode.Shift and 2) ltgt 0 then
• begin
• Include(Shift, ssCtrl)
• end
• if (KeyCode.Shift and 4) ltgt 0 then
• begin
• Include(Shift, ssAlt)
• end
• PostKeyEx32(KeyCode.KeyCode, Shift, False)
• end
• end

16
PostKeyEx32

• // from http//delphi.about.com/od/adptips2004/a/b
  ltip0604_4.htm
• procedure PostKeyEx32(key Word const shift
  TShiftState specialkey Boolean)
• type
• TShiftKeyInfo record
• shift Byte
• vkey Byte
• end
• ByteSet set of 0..7
• const
• shiftkeys array 1..3 of TShiftKeyInfo
• ((shift Ord(ssCtrl) vkey VK_CONTROL),
• (shift Ord(ssShift) vkey VK_SHIFT),
• (shift Ord(ssAlt) vkey VK_MENU))
• var
• flag DWORD
• bShift ByteSet absolute shift
• j Integer

• begin
• for j 1 to 3 do
• begin
• if shiftkeysj.shift in bShift then
• keybd_event(shiftkeysj.vkey,
• MapVirtualKey(shiftkeysj.vkey, 0), 0,
  0)
• end
• if specialkey then
• flag KEYEVENTF_EXTENDEDKEY
• else
• flag 0
• keybd_event(key, MapvirtualKey(key, 0), flag,
  0)
• flag flag or KEYEVENTF_KEYUP
• keybd_event(key, MapvirtualKey(key, 0), flag,
  0)
• for j 3 downto 1 do
• begin
• if shiftkeysj.shift in bShift then

17
Comparing Appearances of Visual Components

• PaintControlToBitMap(frmGridTest.TestGrid,
• TestBitMap, True)
• frmGridTest.Hide
• BitmapKey
• RbwDataGridAutoWordWrapAdjustRowHeight
• UserPrompt
• 'Has the text in the string and boolean
  cells word wrapped '
• 'and have the rows expanded to
  accommodate the text?'
• Result CompareAndUpdateBitmap(BitmapKey,
  UserPrompt,
• TestBitMap)

18
PaintControlToBitMap

• Procedure PaintControlToBitMap(Control TControl
• BitMap TBitMap IncludeCursor boolean)
• begin
• // Set the size of the bitmap that will hold the
  image of Control
• BitMap.Width Control.Width
• BitMap.Height Control.Height
• if Control is TWinControl then
• begin
• TWinControl(Control).PaintTo(BitMap.Canvas,
  0, 0)
• end
• else if Control is TGraphicControl then
• begin
• // Get a screen capture of the form
  containing the TGraphicControl
• // and copy only the portion of that screen
  capture that contains
• // the TGraphicControl into BitMap.

19
CompareAndUpdateBitmap

• function CompareAndUpdateBitmap(const BitmapKey,
  UserPrompt string
• TestBitMap TBitmap) Boolean
• var
• PredefinedBitMap TBitmap
• begin
• PredefinedBitMap FBitmapStorage.BitMapCollect
  ion.Find(BitmapKey)
• result CompareBitMaps(TestBitMap,
  PredefinedBitMap)
• if not result and (TestMethod tmScripted)
  then
• begin
• result UserCompareBitMap(PredefinedBitMap,
  TestBitMap, UserPrompt)

• if result then
• begin
• if PredefinedBitMap nil then
• begin
• FBitmapStorage.
• BitMapCollection.Store(BitmapKey,
• TestBitMap)
• end
• else
• begin
• PredefinedBitMap.Assign(
• TestBitMap)
• end
• end
• end
• end

20
Limitations

• Someone has to check the appearance of a control
  manually at least once.
• There can be no manual use of the mouse or
  keyboard during a test.
• Changes to the computer outside of the control of
  the test, such as changing from small to large
  fonts, will affect the bitmap comparisons.

21
Summary

• DUnit can be used to test visual controls.
• Manual user interaction during tests can be
  reduced but not entirely eliminated.
• The tests are fragile They are easily affected
  by changes to the computer outside the test.