Fix: ToTrace extension method can handle null values.

Author: tusmester

src/SenseNet.Tools.Tests/SnTraceTests.cs

@@ -1,4 +1,5 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using SenseNet.Diagnostics;
 using System.Linq;
 using System.Reflection;
@@ -438,5 +439,58 @@ public void SnTrace_DynamicCategoryOnOff()
             Assert.AreEqual("0124579BCDE", actual);
         }
 
+        [TestMethod]
+        public void SnTrace_ToTrace_String()
+        {
+            string s1 = null;
+            var s2 = string.Empty;
+            var s3 = "short";
+            var s4 = "loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong";
+
+            Assert.AreEqual(string.Empty, s1.ToTrace());
+            Assert.AreEqual(string.Empty, s2.ToTrace());
+            Assert.AreEqual("short", s3.ToTrace());
+            Assert.AreEqual("looooooooooooooooooo", s4.ToTrace(20));
+        }
+
+        [TestMethod]
+        public void SnTrace_ToTrace_Array_Int()
+        {
+            int[] a1 = null;
+            var a2 = Array.Empty<int>();
+            var a3 = new[] { 1, 2 };
+
+            Assert.AreEqual(string.Empty, a1.ToTrace());
+            Assert.AreEqual("[]", a2.ToTrace());
+            Assert.AreEqual("[1, 2]", a3.ToTrace());
+            Assert.AreEqual("[1, ...]", a3.ToTrace(1));
+        }
+        [TestMethod]
+        public void SnTrace_ToTrace_Array_String()
+        {
+            string[] a1 = null;
+            var a2 = Array.Empty<string>();
+            var a3 = new[] { "s1", "s2", null };
+
+            Assert.AreEqual(string.Empty, a1.ToTrace());
+            Assert.AreEqual("[]", a2.ToTrace());
+            Assert.AreEqual("[s1, s2, ]", a3.ToTrace());
+            Assert.AreEqual("[s1, ...]", a3.ToTrace(1));
+        }
+
+        [TestMethod]
+        public void SnTrace_ToTrace_Dictionary_StringString()
+        {
+            Dictionary<string, string> d1 = null;
+            var d2 = new Dictionary<string, string>()
+            {
+                { "key1", null },
+                { "key2", "value2" },
+                { "key3", "loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong" },
+            };
+
+            Assert.AreEqual(string.Empty, d1.ToTrace());
+            Assert.AreEqual("key1: {null}, key2: value2 (6), key3: looooooooooooooooooo... (77)", d2.ToTrace());
+        }
     }
 }

src/SenseNet.Tools/Diagnostics/SnTraceExtensions.cs

@@ -6,14 +6,36 @@ namespace SenseNet.Diagnostics
 {
     public static class SnTraceExtensions
     {
-        public static string ToTrace(this string text, int maxLength = 100) =>
-            text.Length < maxLength ? text : text.Substring(0, maxLength);
+        public static string ToTrace(this string text, int maxLength = 100)
+        {
+            if (string.IsNullOrEmpty(text))
+                return string.Empty;
 
-        public static string ToTrace(this IEnumerable<int> items, int maxCount = 32) =>
-            Format(items.Take(maxCount + 1).Select(x => x.ToString()).ToArray(), maxCount);
+            return text.Length < maxLength ? text : text.Substring(0, maxLength);
+        }
 
-        public static string ToTrace(this IEnumerable<string> items, int maxCount = 10) =>
-            Format(items.Take(maxCount + 1).ToArray(), maxCount);
+        public static string ToTrace(this IEnumerable<int> items, int maxCount = 32) => items == null
+            ? string.Empty
+            : Format(items.Take(maxCount + 1).Select(x => x.ToString()).ToArray(), maxCount);
+
+        public static string ToTrace(this IEnumerable<string> items, int maxCount = 10) => items == null
+            ? string.Empty
+            : Format(items.Take(maxCount + 1).ToArray(), maxCount);
+
+        public static string ToTrace(this IDictionary<string, string> data)
+        {
+            if (data == null)
+                return string.Empty;
+
+            return string.Join(", ", data.Select(x =>
+            {
+                if (x.Value == null)
+                    return $"{x.Key}: {{null}}";
+                return $"{x.Key}: " +
+                       $"{(x.Value.Length > 20 ? x.Value.Substring(0, 20) + "..." : x.Value)} " +
+                       $"({x.Value.Length})";
+            }));
+        }
 
         private static string Format(string[] set, int maxCount) =>
             $"[{string.Join(", ", set.Take(maxCount))}{(set.Length > maxCount ? ", ...]" : "]")}";