public void ToStringTest()
        {
            Assert.AreEqual("Max", Enum <TestULongEnum> .ToString(TestULongEnum.Max));
            Assert.AreEqual("0", Enum <EmptyEnum> .ToString(default(EmptyEnum)));
            Assert.AreEqual("None", Enum <TestLongEnum> .ToString(default(TestLongEnum)));
            Assert.AreEqual("Alpha", Enum <TestLongEnum> .ToString(TestLongEnum.Alpha));
            Assert.AreEqual("-2147483648", Enum <EmptyEnum> .ToString((EmptyEnum)(1 << 31)));
            Assert.AreEqual("-2147483647", Enum <EmptyEnum> .ToString((EmptyEnum)((1 << 31) | 1)));
            Assert.AreEqual("1, -2147483648", Enum <EmptyEnum> .ToString((EmptyEnum)((1 << 31) | 1), EnumFormattingOptions.DistinctFlags));

            Assert.AreNotEqual("-10", Enum <TestULongEnum> .ToString(unchecked ((TestULongEnum)(-10))));
            Assert.AreEqual("-10", Enum <TestLongEnum> .ToString((TestLongEnum)(-10)));
            Assert.AreEqual("-10", Enum <TestIntEnum> .ToString((TestIntEnum)(-10)));

            TestLongEnum e = TestLongEnum.Gamma | TestLongEnum.Alphabet;

            Assert.AreEqual("Alphabet, Gamma", e.ToString(EnumFormattingOptions.Auto));
            Assert.AreEqual("7", e.ToString(EnumFormattingOptions.NonFlags));
            Assert.AreEqual("Alpha, Beta, Gamma", e.ToString(EnumFormattingOptions.DistinctFlags));
            Assert.AreEqual("Alphabet, Gamma", e.ToString(EnumFormattingOptions.CompoundFlagsOrNumber));
            Assert.AreEqual("Alphabet, Gamma", e.ToString(EnumFormattingOptions.CompoundFlagsAndNumber));

            e += 16;
            Assert.AreEqual("23", e.ToString(EnumFormattingOptions.Auto));
            Assert.AreEqual("23", e.ToString(EnumFormattingOptions.NonFlags));
            Assert.AreEqual("Alpha, Beta, Gamma, 16", e.ToString(EnumFormattingOptions.DistinctFlags));
            Assert.AreEqual("23", e.ToString(EnumFormattingOptions.CompoundFlagsOrNumber));
            Assert.AreEqual("16, Alphabet, Gamma", e.ToString(EnumFormattingOptions.CompoundFlagsAndNumber));

            TestIntEnum ie = TestIntEnum.Simple | TestIntEnum.Normal | TestIntEnum.Risky;

            Assert.AreEqual("Simple, Normal, Risky", ie.ToString(EnumFormattingOptions.Auto));
        }
        public void ParseTest()
        {
            Assert.AreEqual(default(EmptyEnum), Enum <EmptyEnum> .Parse("0"));
            Assert.AreEqual(default(EmptyEnum), Enum <EmptyEnum> .Parse("0".AsSegment()));
#if !(NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
            Assert.AreEqual(default(EmptyEnum), Enum <EmptyEnum> .Parse("0".AsSpan()));
#endif
            Assert.AreEqual(TestULongEnum.Max, Enum <TestULongEnum> .Parse("Max"));
            Assert.AreEqual(TestULongEnum.Max, Enum <TestULongEnum> .Parse("Max".AsSegment()));
#if !(NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
            Assert.AreEqual(TestULongEnum.Max, Enum <TestULongEnum> .Parse("Max".AsSpan()));
#endif
            Assert.AreEqual(TestULongEnum.Max, Enum <TestULongEnum> .Parse(UInt64.MaxValue.ToString()));
            Assert.AreEqual(TestLongEnum.Min, Enum <TestLongEnum> .Parse("Min"));
            Assert.AreEqual(TestLongEnum.Min, Enum <TestLongEnum> .Parse(Int64.MinValue.ToString()));
            Assert.AreEqual(TestLongEnum.Min, Enum <TestLongEnum> .Parse(" -9223372036854775808 "));
            Assert.AreEqual(TestLongEnum.Max, Enum <TestLongEnum> .Parse("9223372036854775807"));
            Assert.AreEqual((EmptyEnum)(-10), Enum <EmptyEnum> .Parse("-10"));

            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("Alpha"));
            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("AlphaRedefined"));
            Assert.AreEqual(TestLongEnum.AlphaRedefined, Enum <TestLongEnum> .Parse("AlphaRedefined"));
            Assert.AreEqual(TestLongEnum.AlphaRedefined, Enum <TestLongEnum> .Parse("Alpha"));
            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("alpha", true));
            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("ALPHAREDEFINED", true));
            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("ALPHAREDEFINED".AsSegment(), true));
#if !(NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
            Assert.AreEqual(TestLongEnum.Alpha, Enum <TestLongEnum> .Parse("ALPHAREDEFINED".AsSpan(), true));
#endif

            TestLongEnum e = TestLongEnum.Gamma | TestLongEnum.Alphabet;
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Gamma, Alphabet"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Gamma, Alphabet".AsSegment()));
#if !(NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Gamma, Alphabet".AsSpan()));
#endif
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("7"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Alpha, Beta, Gamma"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Alpha Beta Gamma", " "));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Alpha | Beta | Gamma", "|"));

            e += 16;
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("23"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("Alpha, Beta, Gamma, 16"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("16, Gamma, Alphabet"));
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("16, Gamma, Alphabet".AsSegment()));
#if !(NETFRAMEWORK || NETSTANDARD2_0 || NETCOREAPP2_0)
            Assert.AreEqual(e, Enum <TestLongEnum> .Parse("16, Gamma, Alphabet".AsSpan()));
#endif

            Assert.IsFalse(Enum <TestLongEnum> .TryParse(UInt64.MaxValue.ToString(), out var _));
            Assert.IsFalse(Enum <TestLongEnum> .TryParse("Beta, Gamma, , Delta, 16", out var _));
            Assert.IsFalse(Enum <TestLongEnum> .TryParse(" ", out var _));
            Assert.IsFalse(Enum <TestLongEnum> .TryParse("9223372036854775808", out var _));
            Assert.IsFalse(Enum <TestLongEnum> .TryParse(" -9223372036854775809 ", out var _));

            TestIntEnum ie = TestIntEnum.Simple | TestIntEnum.Normal | TestIntEnum.Risky;
            Assert.AreEqual(ie, Enum <TestIntEnum> .Parse(ie.ToString(EnumFormattingOptions.Auto)));
        }