Ok what's the trick to do this?

[Net Doe]

I have a VBA program that takes data from similarly formatted
sheets, and present the data onto one sheet, as seen below as
an example

TestNum Value State
1 10 On
4 Off
2 Off
2 8 On
5 On
2 Off

Now I want to be fancy and put a drop-down list on the TestNum
cell so users can choose a certain TestNum and ONLY data for that
TestNum will be show, as seen below if TestNum=2 is chosen

TestNum Value State
2 8 On
5 On
2 Off

However, by default, I want to show ALL test data. Is this easily done
in VBA?

 

[Net Doe]

Actually the drop-down list is on the cell below the TestNum column
header. If a user selects "All" this cell will show "1" instead of "All"
after the data is displayed. If a user selects a certain test number,
the cell content will remain that test number. I don't know if this
is possible.