public void GenerateOneMillionInt64_WithRngProvider_ShouldBeUnique() { const int count = 1000000; var numbersHolder = new long[count]; using var rngProvider = new RNGCryptoServiceProvider(); for (var i = 0; i < count; i++) { numbersHolder[i] = rngProvider.GetInt64(13); } numbersHolder.Should().NotBeEmpty().And.NotContainNulls().And.HaveCount(count).And.OnlyHaveUniqueItems(); }