Swatching for work in the round is necessary because people often have different tensions between how they work a knit and a purl. This method of working a flat swatch from the front wastes less yarn and is neater than leaving a long loop across the back of every row. Watch this how to video and learn to swatch a round without wasting so much yarn.
1) Cast on X stitches on a double pointed or circular needle.
2) Estimate how much yarn a row of stitches in pattern takes. Either work a row and tink back or wrap the yarn around the needle, each wrap equaling a stitch. Too much is better than too little.
3) Push the work back to the beginning of the row, rather than turning. Strand the estimated amount of yarn across the back.
4) Work a row with the yarn from the ball.
5) Push the work back to the beginning of the row, rather than turning.
6) Work the row using the yarn stranded across the back.
7) Repeat these steps until the swatch is big enough.