System.Tests.StringTests.IndexOf_SingleLetter C# (CSharp) Method

        public static void IndexOf_SingleLetter(string s, char target, int startIndex, int count, int expected)
        {
            bool safeForCurrentCulture =
                IsSafeForCurrentCultureComparisons(s)
                && IsSafeForCurrentCultureComparisons(target.ToString());

            if (count + startIndex == s.Length)
            {
                if (startIndex == 0)
                {
                    Assert.Equal(expected, s.IndexOf(target));
                    Assert.Equal(expected, s.IndexOf(target.ToString(), StringComparison.Ordinal));
                    Assert.Equal(expected, s.IndexOf(target.ToString(), StringComparison.OrdinalIgnoreCase));

                    // To be safe we only want to run CurrentCulture comparisons if
                    // we know the results will not vary depending on location
                    if (safeForCurrentCulture)
                    {
                        Assert.Equal(expected, s.IndexOf(target.ToString()));
                        Assert.Equal(expected, s.IndexOf(target.ToString(), StringComparison.CurrentCulture));
                    }
                }
                Assert.Equal(expected, s.IndexOf(target, startIndex));
                Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, StringComparison.Ordinal));
                Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, StringComparison.OrdinalIgnoreCase));

                if (safeForCurrentCulture)
                {
                    Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex));
                    Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, StringComparison.CurrentCulture));
                }
            }
            Assert.Equal(expected, s.IndexOf(target, startIndex, count));
            Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, count, StringComparison.Ordinal));
            Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, count, StringComparison.OrdinalIgnoreCase));

            if (safeForCurrentCulture)
            {
                Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, count));
                Assert.Equal(expected, s.IndexOf(target.ToString(), startIndex, count, StringComparison.CurrentCulture));
            }
        }