@Test
public void testAngleAxis() {

  final Matrix4 mat4A = new Matrix4();
  // rotate identity 90 degrees around X
  final double angle = MathUtils.HALF_PI;
  mat4A.fromAngleAxis(MathUtils.HALF_PI, Vector3.UNIT_X);
  assertEquals(new Matrix4( //
      1, 0, 0, 0, //
      0, Math.cos(angle), -Math.sin(angle), 0, //
      0, Math.sin(angle), Math.cos(angle), 0, //
      0, 0, 0, 1), mat4A);
}