### Question:
Vector2f extends AVector2 { public static Vector2f zero() { return new Vector2f(); } private  Vector2f(); private  Vector2f(final double x, final double y); static Vector2f fromX(final double x); static Vector2f fromY(final double y); static Vector2f fromXY(final double x, final double y); static Vector2f fromAngle(final double angle); static Vector2f fromAngleLength(final double angle, final double length); static Vector2f copy(final IVector2 xy); static Vector2f zero(); @Override IVector2 copy(); @Override Vector2 getXYVector(); @Override double x(); @Override double y(); static final Vector2f X_AXIS; static final Vector2f Y_AXIS; static final Vector2f ZERO_VECTOR; }### Answer:
@Test public void testZero() { Vector2f zero = Vector2f.zero(); assertThat(zero.x()).isEqualTo(0.0); assertThat(zero.y()).isEqualTo(0.0); }