muckrake vs put to the test

muckrake

noun
  • A rake for scraping up dung. 

verb
  • To search for and expose corruption or scandal, especially as a form of investigative journalism. 

put to the test

verb
  • To test something or someone; to evaluate, scrutinize or explore by testing or experimentation. 

How often have the words muckrake and put to the test occurred in a corpus of books? (source: Google Ngram Viewer )