### Question:
LineSegment extends ALine implements ILineSegment { @Override public IHalfLine toHalfLine() { return HalfLine.createNewWithoutCopy(getStart(), directionVector()); } @SuppressWarnings("unused") private  LineSegment(); private  LineSegment(final IVector2 start, final IVector2 end); static ILineSegment fromOffset(final IVector2 supportVector, final IVector2 offset); static ILineSegment fromPoints(final IVector2 start, final IVector2 end); @Override boolean isValid(); @Override final boolean equals(final Object other); @Override final int hashCode(); @Override IVector2 getStart(); @Override IVector2 getEnd(); @Override IVector2 getCenter(); @Override double getLength(); @Override IVector2 directionVector(); @Override IVector2 closestPointOnLine(final IVector2 point); @Override ILine toLine(); @Override IHalfLine toHalfLine(); @Override ILineSegment copy(); @Override Optional<IVector2> intersectLine(final ILine line); @Override Optional<IVector2> intersectHalfLine(final IHalfLine halfLine); @Override Optional<IVector2> intersectSegment(final ILineSegment other); @Override IVector2 stepAlongLine(final double stepSize); @Override ILineSegment withMargin(final double margin); @Override String toString(); @Override List<IVector2> getSteps(final double stepSize);  }### Answer:
@Test public void testToHalfLine() { IVector2 start = Vector2.fromXY(10, 20); IVector2 end = Vector2.fromXY(30, 40); ILineSegment segment = LineSegment.fromPoints(start, end); IHalfLine line = segment.toHalfLine(); assertThat(line.supportVector(), is(segment.getStart())); assertThat(line.directionVector(), is(segment.directionVector())); }