public void testConcat() {
assertTrue(Arrays.equals(EMPTY, Doubles.concat()));
assertTrue(Arrays.equals(EMPTY, Doubles.concat(EMPTY)));
assertTrue(Arrays.equals(EMPTY, Doubles.concat(EMPTY, EMPTY, EMPTY)));
assertTrue(Arrays.equals(ARRAY1, Doubles.concat(ARRAY1)));
assertNotSame(ARRAY1, Doubles.concat(ARRAY1));
assertTrue(Arrays.equals(ARRAY1, Doubles.concat(EMPTY, ARRAY1, EMPTY)));
assertTrue(
Arrays.equals(
new double[] {(double) 1, (double) 1, (double) 1},
Doubles.concat(ARRAY1, ARRAY1, ARRAY1)));
assertTrue(
Arrays.equals(
new double[] {(double) 1, (double) 2, (double) 3, (double) 4},
Doubles.concat(ARRAY1, ARRAY234)));
}