A "test batch" refers to a small amount of a product or material that is made to check and evaluate its quality or effectiveness before producing it on a larger scale. Full definition
Some dog food companies simply test batches of food at random throughout production. (topdogtips.com)
I did test a batch with organic cane sugar instead of coconut sugar, and the texture was almost identical but the taste wasn't as rich. (feastingonfruit.com)