constate vs testify

constate

verb
  • To ascertain; to verify; to establish; to prove. 

  • To relay information in a statement and say whether it is true or false. 

testify

verb
  • To make a declaration, or give evidence, under oath. 

  • To make a statement based on personal knowledge or faith. 

How often have the words constate and testify occurred in a corpus of books? (source: Google Ngram Viewer )