Here is a starter code kata… This is practically nothing in VBA since types get auto-converted, but how might you do this taking a variable of type integer and write a function to convert it to a string type. Here is the code kata requirements along with tests we can use to make sure it does what the kata is expecting at this URL: https://www.codewars.com/kata/5265326f5fda8eb1160004c8

Here is the description of the kata from that URL:

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We need a function that can transform a number (integer) into a string.

What ways of achieving this do you know?

Examples (input –> output):

123  --> "123"
999  --> "999"
-100 --> "-100"

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Ok, given this basic kata how would you code a function to convert an integer into a string?

So I started with a blank Access database and using the RubberDuckVBA addin (Download available here: https://rubberduckvba.com/) I created a new test module. I added the RubberDuck VBA reference in Tools -> References and added the Compiler Constant in Tools -> ConvertIntegerToString Properties: LateBindTests = 0

And here is my test module with the updates:

'@TestModule
'@Folder("Tests")

Option Compare Database 

Option Explicit 
Option Private Module 

#Const LateBind = LateBindTests 

#If LateBind Then 
    Private Assert As Object 
    Private Fakes As Object 
#Else 
    Private Assert As Rubberduck.AssertClass 
    Private Fakes As Rubberduck.FakesProvider 
#End If 

'@ModuleInitialize
Private Sub ModuleInitialize() 
    'this method runs once per module.
    #If LateBind Then 
        Set Assert = CreateObject( "Rubberduck.AssertClass") 
        Set Fakes = CreateObject( "Rubberduck.FakesProvider") 
    #Else 
        Set Assert = New Rubberduck.AssertClass 
        Set Fakes = New Rubberduck.FakesProvider 
    #End If 
End Sub 

'@ModuleCleanup
Private Sub ModuleCleanup() 
    'this method runs once per module.
    Set Assert = Nothing 
    Set Fakes = Nothing 
End Sub 

'@TestInitialize
Private Sub TestInitialize() 
    'This method runs before every test in the module..
End Sub 

'@TestCleanup
Private Sub TestCleanup() 
    'this method runs after every test in the module.
End Sub 

'@TestMethod("IntegerToString")
Private Sub Test123() 
    On Error GoTo TestFail 
    
    'Arrange:
    Dim paramIn As Integer 
    Dim funcOut As String 
    paramIn = 123 
    
    'Act:
    funcOut = IntegerToString(paramIn) 
    
    'Assert:
    Assert.AreEqual  "123",funcOut 

TestExit: 
    '@Ignore UnhandledOnErrorResumeNext
    On Error Resume Next 
    
    Exit Sub 
TestFail: 
    Assert.Fail  "Test raised an error: #" & Err.Number &  " - " & Err.Description 
    Resume TestExit 
End Sub 

'@TestMethod("IntegerToString")
Private Sub Test999() 
    On Error GoTo TestFail 
    
    'Arrange:
    Dim paramIn As Integer 
    Dim funcOut As String 
    paramIn = 999 
    
    'Act:
    funcOut = IntegerToString(paramIn) 
    
    'Assert:
    Assert.AreEqual  "999",funcOut 

TestExit: 
    '@Ignore UnhandledOnErrorResumeNext
    On Error Resume Next 
    
    Exit Sub 
TestFail: 
    Assert.Fail  "Test raised an error: #" & Err.Number &  " - " & Err.Description 
    Resume TestExit 
End Sub 

'@TestMethod("IntegerToString")
Private Sub TestNegative100() 
    On Error GoTo TestFail 
    
    'Arrange:
    Dim paramIn As Integer 
    Dim funcOut As String 
    paramIn = -100 
    
    'Act:
    funcOut = IntegerToString(paramIn) 
    
    'Assert:
    Assert.AreEqual  "-100",funcOut 

TestExit: 
    '@Ignore UnhandledOnErrorResumeNext
    On Error Resume Next 
    
    Exit Sub 
TestFail: 
    Assert.Fail  "Test raised an error: #" & Err.Number &  " - " & Err.Description 
    Resume TestExit 
End Sub 

The module is just boiler plate up to the tests themselves where I created three tests to test for the three integer to string conversion conditions of the kata. These tests start at the first line: ‘@TestMethod(“IntegerToString”)

These tests need a public function called IntegerToString to compile so here is a new module I created called KataModule with that function:

Option Compare Database 
Option Explicit 

Public Function IntegerToString(intVal As Integer) As String 
    IntegerToString = intVal 
End Function 

And this function passes all the tests. Kata complete!

Here is my database via zip file you can download. Remember, I used RubberDuckVBA to write the tests. Follow my instructions above after installing the add-in by going to the VBE environment (Alt-F11 or Ctrl-G to go to the Immediate Window) and using the Tools menu there.