assertEquals(expected, BigIntegerMath.factorial(i));
    }
  }

  public void testFactorial0() {
    assertEquals(BigInteger.ONE, BigIntegerMath.factorial(0));
  }

  public void testFactorialNegative() {
    assertThrows(IllegalArgumentException.class, () -> BigIntegerMath.factorial(-1));
  }

  public void testBinomialSmall() {
    runBinomialTest(0, 30);
  }

  @GwtIncompatible // too slow

    assertThat(DoubleMath.factorial(DoubleMath.MAX_FACTORIAL + 1)).isPositiveInfinity();
    assertThat(DoubleMath.factorial(DoubleMath.MAX_FACTORIAL + 20)).isPositiveInfinity();
  }

  public void testFactorialNegative() {
    for (int n : NEGATIVE_INTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> DoubleMath.factorial(n));
    }
  }

    assertThat(DoubleMath.factorial(DoubleMath.MAX_FACTORIAL + 1)).isPositiveInfinity();
    assertThat(DoubleMath.factorial(DoubleMath.MAX_FACTORIAL + 20)).isPositiveInfinity();
  }

  public void testFactorialNegative() {
    for (int n : NEGATIVE_INTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> DoubleMath.factorial(n));
    }
  }

      int expectedInt = fitsInInt(expectedBig) ? expectedBig.intValue() : Integer.MAX_VALUE;
      assertEquals(expectedInt, IntMath.factorial(n));
    }
  }

  public void testFactorialNegative() {
    for (int n : NEGATIVE_INTEGER_CANDIDATES) {
      assertThrows(IllegalArgumentException.class, () -> IntMath.factorial(n));
    }
  }

  // Depends on the correctness of BigIntegerMath.binomial.