DUnit Cannot create form. No MDI forms are currently active - delphi

Question

Hey there i have a problem with my Unit Testing in Delphi XE3 i have a project that consist of 1 MDIForm and allot of MDIChild forms then problem is that when i run test on my MDIChild forms i get this error:
TestAllDataSrouces: EInvalidOperation
at $0064346F
SetUp FAILED: Cannot create form. No MDI forms are currently active
my Setup method looks like this:
procedure TestTCustomerCard.SetUp;
begin
FCustomerCard := TCustomerCard.Create(Application);
end;
what can i do to solve this error? so far i tried:
FCustomerCard := TCustomerCard.Create(Application.MainForm);
FCustomerCard := TCustomerCard.Create(nil);
And
procedure TestTCustomerCard.SetUp;
var
a : TForm;
begin
a := TForm.Create(nil);
a.FormStyle := fsMDIForm;
FCustomerCard := TCustomerCard.Create(a);
end;
and my test is:
procedure TestTCustomerCard.TestAllDataSrouces;
var
I: Integer;
begin
for I := 0 to FCustomerCard.ComponentCount-1 do
begin
if (FCustomerCard.Components[i] is TcxLookupComboBox) then
begin
Check(TcxLookupComboBox(FCustomerCard.Components[i]).Properties.ListSource = nil,'Error no ListSource, Lookup: '+TcxLookupComboBox(FCustomerCard.Components[i]).Name+' Parent: '+TcxLookupComboBox(FCustomerCard.Components[i]).Parent.Name);
end;
if (FCustomerCard.Components[i] is TcxDBTextEdit) then
begin
Check(TcxDBTextEdit(FCustomerCard.Components[i]).DataBinding.DataSource = nil,'Error No DataSet, Text Edit: '+TcxDBTextEdit(FCustomerCard.Components[i]).Name+' Parent: '+TcxDBTextEdit(FCustomerCard.Components[i]).Parent.Name);
end;
if (FCustomerCard.Components[i] is TcxGridDBTableView) then
begin
Check(TcxGridDBTableView(FCustomerCard.Components[i]).DataController.DataSource = nil,'Error no Data Source, DB Grid View: '+TcxGridDBTableView(FCustomerCard.Components[i]).Name);
end;
end;
end;
Demo Project: Here

Answer 1

What you are doing is more like a functional or integration test. You are checking that your UI is correctly set up. That kind of test is different from a unit test.
Unit tests are supposed to check that if you give a module certain inputs, then they produce certain outputs. Unit tests are localized. They are meant to test the behaviour of a unit independently from other units. A UI specifically depends on other units. They take data from input devices and operate on databases and on the whole have quite complicated set of dependencies. That makes them a bad target for unit testing.
Take a look at this question - Unit tests vs Functional tests
To do the kind of testing you want, it is probably best to make your own tool that can set up the environment correctly and perform the test.

Answer 2

The error message pinpoints the problem. If you need an MDI child form, it must have an MDI parent form. And that parent form must be the main form of your program. Hard to achieve in a DUnit project. Your solutions appear to be:
Make the main form of your program be an MDI main form. I think that will be tricky to achieve.
Make your form under test not be an MDI child form.
Find a way to test that does not require instantiation of this form.

Answer 3

I have encountered the same problem, and I decided to implement advice of David Heffernan and "Make your form under test not be an MDI child form".
Here I will describe how I could reach this. I have made all changes in my testcase unit.
Make test form that inherits original MDI child form
type TTestCustomerCard = class(TCustomerCard) end;
Add this just before your test case class.
Copy dfm file or the form, say CustomerCard.dfm, to TestCustomerCard.dfm
Open TestCustomerCard.dfm in any text editor, delete line
FormStyle = fsMDIChild (because fsNormal is default value),
change first line
object CustomerCard: TCustomerCard
to
object TestCustomerCard: TTestCustomerCard
Add directive
{$R TestCustomerCard.dfm }
In your SetUp method instead of
FCustomerCard := TCustomerCard.Create(Application);
write
FCustomerCard := TTestCustomerCard.CreateNew(Application);
InitComponentRes( 'TTESTCUSTOMERCARD', FCustomerCard );