TESTING COM AND WEB SERVICES in Font

Maker PDF417 in Font TESTING COM AND WEB SERVICES

Figure 10-11. The Object Browser window displaying the Acrobat Access library contents Of course, the next question is, How do you know what s in this library and how it works The Object Browser will show you the contents and you can explore the methods and classes within the library, but you ll get only limited information about them (similar to what you see in Figure 10-11). In order to test this library, you ll have to be very familiar with the software already or you ll need to have a software requirements document or Test Plan to guide you. Chances are you aren t an expert at the internals of Adobe Acrobat software, so this particular library won t be easy to reference and test without the associated planning documentation you should have on any good automated test project. Still, you want to get a feel for how to work with these libraries, so in Exercise 10-3 you ll reference and test a method of a library many of us are more familiar with the Excel spreadsheet library.

Test Setup: Assume that you are assigned to the Excel test team and your job is to test the following requirement: Test Requirement: Test the principal interest formula within the Microsoft Excel object library. Test its basic functionality by providing simple inputs and testing the output to verify correct results. Expected Result: Excel s PMT formula for calculating interest will return a correct calculation. 1. Start Visual Studio and create a new Windows Forms application in VB .NET or C#. Name it ComTestBed. 2. Set a reference to the Microsoft Excel COM library by selecting Project Add References from the main menu. The Add Reference dialog box will display (again, see Figure 10-9) 3. In the Add Reference dialog box, click the COM tab. 4. Scroll down in the dialog until you find the Microsoft Excel Object Library. (If you have more than one version of this library available, select the highest version number. This code was written using the Excel 10.0 Object Library.) Click OK to add this library to your list of references for this project. 5. To see the library you just added, expand the References folder in the Solution Explorer window. (For VB .NET: To see the added library, you must click the Show All Files button in the Solution Explorer window. Clicking the Show All Files button displays the References folder in the Solution Explorer window.) 6. Place a button on the form and set its text property to Automate. Place three textboxes on the form and change their name properties to txtInterest, txtMonths, and txtPrincipal, respectively. 7. For each textbox, add a label control and change the text properties of these labels to read Interest, Months, and Principal, respectively. Arrange the textboxes and label controls as desired. Your form should look similar to Figure 10-12.

Figure 10-12. Layout of controls for the COM test bed 8. Now, add the following code to the Click event of your new button:

VB .NET Dim xlApp As New Excel._ExcelApplication Dim loanpayment As Decimal Dim dblInterest, dblMonths, dblprincipal As Double dblprincipal = Convert.ToDouble(txtPrincipal.Text) dblMonths = Convert.ToDouble(txtMonths.Text) dblInterest = Convert.ToDouble(txtInterest.Text) loanpayment = xlApp.WorksheetFunction.Pmt _ (dblInterest / 12, dblMonths, dblprincipal) MessageBox.Show("the monthly payment is: " & _ Format(Math.Abs(loanpayment), "$#.##"), "Mortgage") C# Excel.Application xlApp = new Excel.Application(); double loanpayment; double dblInterest; double dblMonths; double dblprincipal; dblprincipal = Convert.ToDouble(txtPrincipal.Text); dblMonths = Convert.ToDouble(txtMonths.Text); dblInterest = Convert.ToDouble(txtInterest.Text); loanpayment = xlApp.WorksheetFunction.Pmt( dblInterest / 12, dblMonths, dblprincipal, 0, 0); MessageBox.Show("the monthly payment is: " + Convert.ToString(Math.Abs(loanpayment)), "Mortgage"); 9. Run the application by pressing F5. Enter some data to verify the code works. This is not a test at this point. So far, you re just verifying functionality. In the next step, you ll set this up as a test. 10. Return to the Code window and, following the information below, write code to return a test pass or test fail condition using a branching statement, such as an If-Then-Else or a Select-Case statement. The principal interest formula is the following: P = Principal: the initial amount of the loan I = The annual interest rate (from 1 to 100 percent) L = Length: the length (in years) of the loan, or at least the length over which the loan is amortized J = Monthly interest in decimal form = I / (12 x 100) N = Number of months over which loan is amortized = L x 12 So, given the variable definitions here, the monthly payment (M) formula is M = P x J/ (1-(1+J)^ - N This is the formula we use in the following code. Add this code to the end of the button1 Click event to calculate the principal interest formula programmatically: