 
 <prompt> Wetin dem dey call di part of tree wey don fall or dem don cut off, wey dem dey use for di past to build cabins? Given di last question, write one context wey contain di answer. <response>: Di practice of component interface testing fit dey use to check how data dey waka between different units, or subsystem components, pass full integration testing between those units. The data wey dey pass fit be like "message packets" and dem fit check the range or data types, for data wey dey come from one unit, and test am to see if e dey valid before e go enter another unit. One option for interface testing na to dey keep separate log file of data items wey dey pass, often with timestamp wey dey logged to allow analysis of thousands of cases of data wey dey pass between units for days or weeks. Tests fit include checking how some extreme data values dey behave while other interface variables dey pass as normal values. Unusual data values for interface fit help explain why performance dey unexpected for the next unit. Component interface testing na one kind of black-box testing, with focus on the data values pass just the related actions of a subsystem component. 