The evidence that I shall give shall be the truth, the whole truth, and nothing but the truth. The information provided by the first witness was true. There is some truth to what the other witness said. Every piece of this information can be researched further. Generally, both information and truth are uncountable. Sometimes, there are some truths that are not stated in an argument.

You can also say "all truth" and "whole information", they're just rarer.

Bit confused by your question. 'The whole ...' does not make 'truth' countable. For example, 'he ate the whole cake' = 'cake' here is uncountable. 'All the' can be used with countable or uncountable nouns - 'he are all the cake' or 'he ate all the cakes'. ('Cake', like many nouns, is both countable and uncountable.)