checker/tests/units/PolyUnitTest.java

import org.checkerframework.checker.units.qual.PolyUnit;
import org.checkerframework.checker.units.qual.m;
import org.checkerframework.checker.units.qual.s;
import org.checkerframework.checker.units.util.UnitsTools;

public class PolyUnitTest {

  @PolyUnit int triplePolyUnit(@PolyUnit int amount) {
    return 3 * amount;
  }

  void testPolyUnit() {
    @m int m1 = 7 * UnitsTools.m;
    @m int m2 = triplePolyUnit(m1);

    @s int sec1 = 7 * UnitsTools.s;
    @s int sec2 = triplePolyUnit(sec1);

    // :: error: (assignment)
    @s int sec3 = triplePolyUnit(m1);
  }
}