rehearsal vs test flight

rehearsal

noun
  • The practicing of something which is to be performed before an audience, usually to test or improve the interaction between several participating people, or to allow technical adjustments with respect to staging to be done. 

  • The act of rehearsing or contriving something; the fact of something's being rehearsed. 

  • A preparatory activity analogous to the rehearsal of a show. 

test flight

noun
  • a proving flight; usually of a prototype of a new aircraft design before it goes into production. 

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