Product Managers trying to test desirability for features

ASK USERS IF THEY WANT FEATURE-X BEFORE BUILDING; ASK FORMER USERS IF THEY WOULD'VE STAYED IF FEATURE-X WAS AVAILABLE; BUILD A SMALL PROTOTYPE OF FEATURE-X AND SEE IF IT GETS ANY TRACTION; ASK ACCOUNT MANAGERS IF THEY'VE LOST BUSINESS FOR NOT HAVING FEATURE-X; ASK COMPETITOR'S USERS IF THEY WOULD SWITCH TO YOUR PRODUCT FOR FEATURE-X; RUN A "BUY A FEATURE" EXERCISE INCLUDING FEATURE-X; RUN A MAX-DIFF ANALYSIS INCLUDING FEATURE-X; RUN A CONJOINT ANALYSIS INCLUDING FEATURE-X; RUN TWO VAN-WESTENDOORP ANALYSES WITH AND WITHOUT FEATYURE-X AND CHECK FOR LIFTS IN THE TARGET PRICE; BUILD A SMALL PROTOTYPE OF FEATURE-X AND SEE IF IT GETS ANY TRACTION