Operation check / validation: the act of verifying that software or hardware operates according to specifications; a basic form of testing.
新機能の動作確認を明日行います。
We'll perform a functionality check for the new feature tomorrow.
そのバグは動作確認で再現できなかった。
That bug couldn't be reproduced during the operation check.
ユーザー側で動作確認をして問題がなければ公開します。
If the user-side operation check finds no problems, we'll release it.