Add some simple tests

MediaBrowser.Common/Extensions/StringExtensions.cs

@@ -0,0 +1,37 @@
+#nullable enable
+
+using System;
+
+namespace MediaBrowser.Common.Extensions
+{
+    /// <summary>
+    /// Extensions methods to simplify string operations.
+    /// </summary>
+    public static class StringExtensions
+    {
+        /// <summary>
+        /// Returns the part left of the <c>needle</c>.
+        /// </summary>
+        /// <param name="str">The string to seek.</param>
+        /// <param name="needle">The needle to find.</param>
+        /// <returns>The part left of the <c>needle</c>.</returns>
+        public static ReadOnlySpan<char> LeftPart(this ReadOnlySpan<char> str, char needle)
+        {
+            var pos = str.IndexOf(needle);
+            return pos == -1 ? str : str[..pos];
+        }
+
+        /// <summary>
+        /// Returns the part left of the <c>needle</c>.
+        /// </summary>
+        /// <param name="str">The string to seek.</param>
+        /// <param name="needle">The needle to find.</param>
+        /// <param name="stringComparison">One of the enumeration values that specifies the rules for the search.</param>
+        /// <returns>The part left of the <c>needle</c>.</returns>
+        public static ReadOnlySpan<char> LeftPart(this ReadOnlySpan<char> str, ReadOnlySpan<char> needle, StringComparison stringComparison = default)
+        {
+            var pos = str.IndexOf(needle, stringComparison);
+            return pos == -1 ? str : str[..pos];
+        }
+    }
+}