Fix infinite loop in HelpText.Addline; add unit test + validation

qmfrederik · qmfrederik · commit 95ded2dbcc52 · 2016-12-29T15:15:24.000Z
diff --git a/src/CommandLine/Text/HelpText.cs b/src/CommandLine/Text/HelpText.cs
@@ -206,7 +206,7 @@ public SentenceBuilder SentenceBuilder
         public static HelpText AutoBuild<T>(
             ParserResult<T> parserResult,
             Func<HelpText, HelpText> onError,
-            Func<Example, Example> onExample, 
+            Func<Example, Example> onExample,
             bool verbsIndex = false,
             int maxDisplayWidth = DefaultMaximumLength)
         {
@@ -254,7 +254,7 @@ public static HelpText AutoBuild<T>(
 
             usageAttr.Do(
                 usage => usage.AddToHelpText(auto, true));
-            
+
             usageLines.Do(
                 lines => auto.AddPreOptionsLines(lines));
 
@@ -519,7 +519,7 @@ public static IEnumerable<string> RenderParsingErrorsTextAsLines<T>(
                 yield return line.ToString();
             }
 
-            var mutuallyErrs = 
+            var mutuallyErrs =
                 formatMutuallyExclusiveSetErrors(
                     meaningfulErrors.OfType<MutuallyExclusiveSetError>());
             if (mutuallyErrs.Length > 0)
@@ -619,8 +619,25 @@ public override string ToString()
                 .ToString();
         }
 
-        private static void AddLine(StringBuilder builder, string value, int maximumLength)
+        internal static void AddLine(StringBuilder builder, string value, int maximumLength)
         {
+            if (builder == null)
+            {
+                throw new ArgumentNullException(nameof(builder));
+            }
+
+            if (value == null)
+            {
+                throw new ArgumentNullException(nameof(value));
+            }
+
+            if (maximumLength < 1)
+            {
+                throw new ArgumentOutOfRangeException(nameof(value));
+            }
+
+            value = value.Trim();
+
             builder.AppendWhen(builder.Length > 0, Environment.NewLine);
             do
             {
diff --git a/tests/CommandLine.Tests/Unit/Text/HelpTextTests.cs b/tests/CommandLine.Tests/Unit/Text/HelpTextTests.cs
@@ -12,6 +12,7 @@
 using CommandLine.Text;
 using FluentAssertions;
 using Xunit;
+using System.Text;
 
 namespace CommandLine.Tests.Unit.Text
 {
@@ -657,5 +658,16 @@ public void AutoBuild_with_assembly_company_attribute_only()
                 ReflectionHelper.SetAttributeOverride(null);
             }
         }
+
+        [Fact]
+        public void Add_line_with_two_empty_spaces_at_the_end()
+        {
+            StringBuilder b = new StringBuilder();
+            HelpText.AddLine(b,
+                "Test  ",
+                1);
+
+            Assert.Equal("T" + Environment.NewLine + "e" + Environment.NewLine + "s" + Environment.NewLine + "t", b.ToString());
+        }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -12,6 +12,7 @@`
`12`	`12`	`using CommandLine.Text;`
`13`	`13`	`using FluentAssertions;`
`14`	`14`	`using Xunit;`
	`15`	`+using System.Text;`
`15`	`16`
`16`	`17`	`namespace CommandLine.Tests.Unit.Text`
`17`	`18`	`{`
`@@ -657,5 +658,16 @@ public void AutoBuild_with_assembly_company_attribute_only()`
`657`	`658`	`ReflectionHelper.SetAttributeOverride(null);`
`658`	`659`	`}`
`659`	`660`	`}`
	`661`	`+`
	`662`	`+ [Fact]`
	`663`	`+ public void Add_line_with_two_empty_spaces_at_the_end()`
	`664`	`+ {`
	`665`	`+ StringBuilder b = new StringBuilder();`
	`666`	`+ HelpText.AddLine(b,`
	`667`	`+ "Test ",`
	`668`	`+ 1);`
	`669`	`+`
	`670`	`+ Assert.Equal("T" + Environment.NewLine + "e" + Environment.NewLine + "s" + Environment.NewLine + "t", b.ToString());`
	`671`	`+ }`
`660`	`672`	`}`
`661`	`673`	`}`