New utilities and tests

source/NSubstitute.Elevated/Weaver/MockInjector.cs

@@ -175,7 +175,6 @@ namespace NSubstitute.Elevated.Weaver
 
             type.Methods.Add(ctor);
         }
-
         void Patch(MethodDefinition method)
         {
             if (method.IsCompilerControlled || method.IsConstructor || method.IsAbstract)

source/Unity.Core.Tests/StringExtensionsTests.cs

@@ -82,6 +82,43 @@ namespace Unity.Core.Tests
             Should.Throw<Exception>(() => "abc".Right(-1));
         }
 
+        [Test]
+        public void Truncate_ThatDoesNotShorten_ReturnsSameInstance()
+        {
+            const string text = "abc def";
+            ReferenceEquals(text, text.Truncate(100)).ShouldBeTrue();
+            ReferenceEquals(text, text.Truncate(10)).ShouldBeTrue();
+            ReferenceEquals(text, text.Truncate(text.Length)).ShouldBeTrue();
+        }
+
+        [Test]
+        public void Truncate_ThatShortens_TruncatesAndAddsTrailer()
+        {
+            "abc def".Truncate(6).ShouldBe("abc...");
+            "abc def".Truncate(5).ShouldBe("ab...");
+            "abc def".Truncate(4).ShouldBe("a...");
+            "abc def".Truncate(3).ShouldBe("...");
+
+            "abc def".Truncate(6, "ghi").ShouldBe("abcghi");
+            "abc def".Truncate(5, "ghi").ShouldBe("abghi");
+            "abc def".Truncate(4, "ghi").ShouldBe("aghi");
+            "abc def".Truncate(3, "ghi").ShouldBe("ghi");
+        }
+
+        [Test]
+        public void Truncate_WithTooBigTrailer_ShouldThrow()
+        {
+            Should.Throw<ArgumentException>(() => "abc def".Truncate(2));
+            Should.Throw<ArgumentException>(() => "abc def".Truncate(5, "123456"));
+        }
+
+        [Test]
+        public void Truncate_WithUnderflow_ShouldThrow()
+        {
+            Should.Throw<ArgumentException>(() => "abc def".Truncate(-2));
+            Should.Throw<ArgumentException>(() => "abc def".Truncate(0, "ghi"));
+        }
+
         [Test]
         public void StringJoin_WithEmpty_ReturnsEmptyString()
         {
@@ -144,7 +181,7 @@ namespace Unity.Core.Tests
         }
 
         [Test]
-        public void ExpandTabs_WithNoTabs_Returns_IdenticalString() // i.e. no allocs
+        public void ExpandTabs_WithNoTabs_ReturnsSameInstance() // i.e. no allocs
         {
             const string text = "abc def ghijkl";
             ReferenceEquals(text, text.ExpandTabs(4)).ShouldBeTrue();

source/Unity.Core/EnumerableExtensions.cs

@@ -43,5 +43,8 @@ namespace Unity.Core
 
         public static bool IsNullOrEmpty<T>([CanBeNull] this IEnumerable<T> @this)
         => @this == null || !@this.Any();
+
+        public static IEnumerable<T> SelectMany<T>([NotNull] this IEnumerable<IEnumerable<T>> @this)
+        => @this.SelectMany(_ => _);
     }
 }

source/Unity.Core/StringExtensions.cs

@@ -21,9 +21,7 @@ namespace Unity.Core
 
         [NotNull]
         public static string Left([NotNull] this string @this, int maxChars)
-        {
-            return @this.Substring(0, Math.Min(maxChars, @this.Length));
-        }
+            => @this.Substring(0, Math.Min(maxChars, @this.Length));
 
         [NotNull]
         public static string Mid([NotNull] this string @this, int offset, int maxChars = -1)
@@ -46,6 +44,15 @@ namespace Unity.Core
             return @this.Substring(@this.Length - safeMaxChars, safeMaxChars);
         }
 
+        [NotNull]
+        public static string Truncate([NotNull] this string @this, int maxChars, string trailer = "...")
+        {
+            if (@this.Length <= maxChars)
+                return @this;
+
+            return @this.Left(maxChars - trailer.Length) + trailer;
+        }
+
         [NotNull]
         public static string StringJoin([NotNull] this IEnumerable @this, [NotNull] string separator)
         => string.Join(separator, @this.Cast<object>());