testing ground

noun4

1. •
   A military site that is used for testing weapons.

   • You know, brothers, that West Irian may possibly, possibly, I repeat possibly, also become a testing ground for either atomic weapons or other explosive devices. — 1960
2. •
   A location set up for the testing of vehicles, machinery, agricultural techniques, etc. to ensure that they work as intended.

   • The testing ground shall be not less than 1 ha in area and the length worked not less than 100 m. — 1966
3. •
   (figurative) A situation or thing that allows new ideas, methods, or hypotheses to be tried out.

   • Copper Harbor, where there are known copper veins, was used as a testing ground for the AMT method. — 1973
4. •
   (figurative) A situation or problem that allows people to test how good they are.

   • Autocratic control grows out of the fundamental imposition of a testing ground on all our young people; the institution that teaches the young also tests the young. — 1977