如何使用在测试运行时确定的类来创建特定GUI类的测试对象？

Question

The idea is to have a GUI class name (like JavaRadioButton ) in a string variable, and instantiate a test object of that type using a Description object. Like in:

Dim Descr: Set Descr=Description.Create
Descr.Add "property1", "value"
Descr.Add "property2", "value"
Descr.Add "property3", "value"
Dim MyTO: Set MyTO=JavaRadioButton (Descr)

but with the GUI class ( JavaRadioButton in this case) being parameterized , ie I have the string "JavaRadioButton" in a variable and want to create a testobject of the GUI class that is contained in that variable.

An obvious attempt is to use the "micclass" property, which reports the GUI class name of a test object:

Dim ClassName: ClassName="JavaRadioButton"
Dim Descr: Set Descr=Description.Create
Descr.Add "property1", "value"
Descr.Add "property2", "value"
Descr.Add "property3", "value"
Descr.Add "micclass", ClassName
Dim MyTO: Set MyTO=JavaObject (Descr)

However, afterwards MyTO still is just a JavaObject . For example, it does not support the .Set method as a JavaRadioButton would.

My current "solution" would be to construct a string that contains the assignment, and evaluate this using ExecuteGlobal (or Eval , as shown here):

Dim ClassName: ClassName="JavaRadioButton"
Dim Descr: Set Descr=Description.Create
Descr.Add "property1", "value"
Descr.Add "property2", "value"
Descr.Add "property3", "value"
Descr.Add "micclass", ClassName
Dim MyTO: Set MyTO=Eval (ClassName & "(Descr)")

This seems to work, as long as ClassName and Descr are reachable for Eval , which sometimes is clumsy to achieve. And it requires error handling code, if you want to catch errors.

Isn´t there a way to do this without creating a string containing sourcecode, and executing it?

Note I added the VBScript tag because that´s QTP´s scripting language, however this question is QTP-specific.

Answer 1

I do not have QTP at hand, but you could try something like this were I launch the assumption that the objects are actually functions that return an object with the same name of that function.

Dim ClassName: ClassName="JavaRadioButton"
Dim Descr: Set Descr=Description.Create
Descr.Add "property1", "value"
Descr.Add "property2", "value"
Descr.Add "property3", "value"
Descr.Add "micclass", ClassName

Dim constructor : Set constructor = GetRef(ClassName)
Dim MyTO: Set MyTO=constructor(Descr)

Could you try that and let me know what it is doing? I am seriously curious.

---

EDIT

Basis for the assumption: The JavaScriptButton is a function that returns an object. The function can support arguments. This is a way to implement a builder or even an abstract factory pattern:

Option explicit    

Class Duck

    Private sound_
    Public Name      ' public field, refactor to property

    Public Function Init(n, sound)
        sound_ = sound
        Name = n
        Set Init = me
    End Function

    Public Sub Quack()
        msgbox sound_
    End Sub

End Class


Public Function NormalDuck(name)
     Set NormalDuck = (new Duck).Init(name, "quack, quack")
End Function

Public Function RubberDuck(name)
     Set RubberDuck = (new Duck).Init(name, "squick, squick")
End Function

Public Function DecoyDuck(name)
     Set DecoyDuck = (new Duck).Init(name, "")
End Function

dim myDuck
dim duckBuilder
dim duckName, duckType

duckType = InputBox("What kind of duck do you want?", "DuckType", "NormalDuck")
Set duckBuilder = GetRef(duckType)

duckName = InputBox("What will be its name?", "DuckName", "Donald")
Set myDuck = duckBuilder(duckName)

myDuck.Quack

Note: VBScript supports the set o = (new foo).Init(bar) construct, while the QTP "compiler" will return a syntax error. You'll have to split it into two statements in QTP

Answer 2

This is pretty easy to achieve if you're willing to use ChildObjects rather than regular descriptive programming.

Function GetObj(parent, micClass, desc)
    desc.Add "micclass", micClass
    Set children = parent.ChildObjects(desc)
    If children.Count < 1 Then
        Err.Raise 1, "GetObj", "Object not found"
    ElseIf children.Count > 1 Then
        Err.Raise 1, "GetObj", "Description is not unique, found " & children.Count & " matches"
    End If
    Set GetObj = children(0)
End Function

Usage:

GetObj(oPage, "WebEdit", desc).Set "Set is a specific method"

I don't know how much value this gives you since you still need to have Set as part of the script and not as a string...