# 15 doesn't work and 9 is broken

Like I said, 15 doesn’t work and the test for 9 breaks:

I suspect if you’ve been following along in Excel then you’ve discovered you too make lots of little mistakes as you go. At least I hope so and that it isn’t just me. It is one of the nice things about all those tests … when you break something by making a simple mistake, the tests tell you, you fix it quickly and cheaply, and move on.

• When I see that the 9 test case is also broken it is immediately obvious what I’ve done wrong.

• I fix it quickly. The tests work.

Public Function i2r(i As Integer) As String

Application.Volatile

i2r = ""

If i = 9 Then

i2r = "IX"

i = i - 9

End If

If i >= 10 Then

i2r = i2r + "X"

i = i - 10

End If

If i >= 5 Then

i2r = i2r + "V"

i = i - 5

End If

If i = 4 Then

i2r = i2r + "IV"

End If

While i <= 3 And i > 0

i2r = i2r + "I"

i = i - 1

Wend

End Function

• Then I do a bit of tidying up – moving things around a little.

• For each small change I make, I recalc the tests.

Public Function i2r(i As Integer) As String

Application.Volatile

i2r = ""

If i >= 10 Then

i2r = i2r + "X"

i = i - 10

End If

If i = 9 Then

i2r = i2r + "IX"

i = i - 9

End If

If i >= 5 Then

i2r = i2r + "V"

i = i - 5

End If

If i = 4 Then

i2r = i2r + "IV"

End If

While i <= 3 And i > 0

i2r = i2r + "I"

i = i - 1

Wend

End Function

• Then I do a bit more tidying up.

Public Function i2r(i As Integer) As String

Application.Volatile

i2r = ""

If i >= 10 Then

i2r = i2r + "X"

i = i - 10

End If

If i = 9 Then

i2r = i2r + "IX"

i = i - 9

End If

If i >= 5 Then

i2r = i2r + "V"

i = i - 5

End If

If i = 4 Then

i2r = i2r + "IV"

i = i - 4

End If

While i >= 1

i2r = i2r + "I"

i = i - 1

Wend

End Function

Then I look at the code and I see the obvious pattern.