Added test cases for lexer issue #399

- added (base) test cases for the lexer issues and 2 test files. The d="" luckily seems to 
  behave as expected (did crash in earlier versions)
- found the exact line in the CSS that failed (border with !important) and isolated the test
- updated names of the tests and files
- added a reference test for the non important line (which should always work).
- fixed small spelling error in the css parser.
- added trailing whitespace test for #399, which also crashes the lexer 

Source/External/ExCSS/Model/Values/TermList.cs

@@ -55,14 +55,14 @@ namespace Svg.ExCSS
             }
         }
 
-        internal void AddSeparator(GrammarSegment termSepertor)
+        internal void AddSeparator(GrammarSegment termSeparator)
         {
             if (_items.Count != _separator.Count + 1)
             {
                 throw new NotSupportedException("Must call AddTerm AddSeparator in that order");
             }
 
-            _separator.Add(termSepertor);
+            _separator.Add(termSeparator);
         }
 
         public int Length

Source/External/ExCSS/Parser.Blocks.cs

@@ -556,7 +556,8 @@ namespace Svg.ExCSS
 
             if(HtmlColor.TryFromHex(color, out htmlColor))
                 return AddTerm(htmlColor);
-            return false;
+            
+            return false;    
         }
 
         #region Namespace

Tests/Svg.UnitTests/LexerIssueTests.cs

+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Svg.UnitTests
+{
+
+    /// <summary>
+    /// Some complexer stylesheets seemed to crash the lexer and result in errors (#399)
+    /// Found several issues in the lexer and parser of the SVG file. 
+    /// 
+    /// This test class will test against these issues to prevent the bug from reoccuring
+    /// </summary>
+    [TestClass]
+    public class LexerIssueTests : SvgTestHelper
+    {
+        private const string ResourceStringEmptyDTagFile = "Issue399_LexerIssue.EmptyDTag.svg";
+
+        private const string ResourceStringLexerTemplate = "Issue399_LexerIssue.LexerTestTemplate.svg";
+        private const string LexerTemplateReplaceToken = "/*[REPLACE]*/";
+
+
+        /// <summary>
+        /// We encountered issues in the example file that were caused by an empty d tag in some of the elements
+        /// </summary>
+        [TestMethod]
+        public void Lexer_FileWithEmptyDAttribute_Success()
+        {
+            var xml = GetXMLDocFromResource(GetFullResourceString(ResourceStringEmptyDTagFile));
+            var doc = OpenSvg(xml);
+        }
+
+        /// <summary>
+        /// Stylesheet lexer fails if there is an important after a hex value, this tests the 3 and 6 lenght variants in the file
+        /// </summary>
+        [TestMethod]
+        public void Lexer_ImportantAfterHex_Success()
+        {
+            Assert.Inconclusive("The important after the  hex codes is not working at the moment. Re-enable these tests if the issue is resolved (#399)");
+            //Important should be valid on 3 digit hex
+            GenerateLexerTestFile("border-top: 1px solid #333 !important;");
+            //Important should be valid on 6 digit hex
+            GenerateLexerTestFile("border-top: 1px solid #009c46 !important;");
+            //Whitespace should not break the parser
+            GenerateLexerTestFile("border-bottom: 1px solid #009c46  ;");
+        }
+
+        /// <summary>
+        ///Reference test if there is an important after a non-hex value (should never fail) and on hex without an important
+        /// </summary>
+        [TestMethod]
+        public void Lexer_NoImportantAndImportantAfterNonHex_Success()
+        {
+            //Hex is working, if no !important suffixing it (#399)
+            GenerateLexerTestFile("border-top: 1px solid #009c46;");
+            //Important is not failing on non-hex value
+            GenerateLexerTestFile("border-top: 1px solid red !important;");
+        }
+
+        [TestMethod]
+        public void Lexer_FileWithInvalidHex_ColorTagIsIgnored()
+        {
+            Assert.Inconclusive("This test fails due to a lexer error");
+            GenerateLexerTestFile("color: #0046;");
+        }
+
+        /// <summary>
+        /// Load the lexer template and replace the token with a test value and try generating the svg
+        /// </summary>
+        /// <param name="testContent">Content to test in the template</param>
+        /// <returns></returns>
+        private SvgDocument GenerateLexerTestFile(string testContent)
+        {
+            var str = GetResourceXmlDocAsString(GetFullResourceString(ResourceStringLexerTemplate));
+            str = str.Replace(LexerTemplateReplaceToken, testContent);
+            var xml = GetXMLDocFromString(str);
+            var doc = OpenSvg(xml);
+            return doc;
+        }
+
+    }
+}

Tests/Svg.UnitTests/Resources/Issue399_LexerIssue/EmptyDTag.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="1092" height="453">
+
+  <g transform="translate(40,20)" style="opacity: 1;">
+    <path class="plot-zero" d="M0,0 H1042" style="opacity: 0;"></path>
+		<path class="plot-now" d="" style="opacity: 0;"></path>
+		<path class="plot-now2" d="" style="opacity: 0;"></path>
+  </g>
+  <clipPath id="clip-view-2">
+    <rect width="1042" height="408"></rect>
+  </clipPath>
+  <g style="opacity: 0;"></g>
+  <text class="plot-warning" y="9" x="521" style="opacity: 0;">data loading - 75%</text>
+  <text class="plot-caption" y="14" x="521" style="opacity: 0;"></text>
+</svg>
\ No newline at end of file

Tests/Svg.UnitTests/Resources/Issue399_LexerIssue/LexerTestTemplate.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="1092" height="453">
+  <style type="text/css">
+
+		
+		#footer
+		{
+			/*[REPLACE]*/
+		}
+
+
+	</style>
+  <g transform="translate(40,20)" style="opacity: 1;">
+    <path class="plot-zero" d="M0,0 H1042" style="opacity: 0;"></path>
+    <path class="plot-now" d="" style="opacity: 0;"></path>
+  </g>
+  <clipPath id="clip-view-2">
+    <rect width="1042" height="408"></rect>
+  </clipPath>
+  <g style="opacity: 0;"></g>
+  <text class="plot-warning" y="9" x="521" style="opacity: 0;">data loading - 75%</text>
+  <text class="plot-caption" y="14" x="521" style="opacity: 0;"></text>
+</svg>
\ No newline at end of file

Tests/Svg.UnitTests/Svg.UnitTests.csproj

@@ -58,6 +58,7 @@
     <Compile Include="BoundsTests.cs" />
     <Compile Include="CssQueryTest.cs" />
     <Compile Include="LargeEmbeddedImageTest.cs" />
+    <Compile Include="LexerIssueTests.cs" />
     <Compile Include="MarkerEndTest.cs" />
     <Compile Include="MetafileRenderingTest.cs" />
     <Compile Include="MultiThreadingTest.cs" />
@@ -107,6 +108,10 @@
   <ItemGroup>
     <EmbeddedResource Include="Resources\Issue_Threading\TestFile.svg" />
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="Resources\Issue399_LexerIssue\LexerTestTemplate.svg" />
+    <EmbeddedResource Include="Resources\Issue399_LexerIssue\EmptyDTag.svg" />
+  </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

Tests/Svg.UnitTests/SvgTestHelper.cs

@@ -4,6 +4,7 @@ using System.Diagnostics;
 using System.Drawing;
 using System.Drawing.Imaging;
 using System.IO;
+using System.Text;
 using System.Xml;
 
 namespace Svg.UnitTests
@@ -15,7 +16,7 @@ namespace Svg.UnitTests
         /// Test file path.
         /// </summary>
         [Obsolete("Try not to use the file loader, please use the resource loader to ensure working of tests on all systems")]
-		protected virtual string TestFile
+        protected virtual string TestFile
         {
             get
             {
@@ -129,15 +130,33 @@ namespace Svg.UnitTests
                 Trace.WriteLine("Done XmlDocument loading from resource data.");
                 return xmlDoc;
             }
+        }
+
+        /// <summary>
+        /// Get embedded resource as string from Unit Test resources.
+        /// </summary>
+        /// <param name="fullResourceString">Full Unit Test resource string.</param>
+        /// <returns>Embedded resource data xml as string.</returns>
+        protected virtual string GetResourceXmlDocAsString(string fullResourceString)
+        {
+            using (var s = GetResourceStream(fullResourceString))
+            {
+                Trace.WriteLine("Load XmlDocument content from resource data.");
+                using (var reader = new StreamReader(s, Encoding.UTF8))
+                {
+                    string value = reader.ReadToEnd();
+                    Trace.WriteLine("Done XmlDocument content loading from resource data.");
+                    return value;
+                }
+            }
         }
 
-
         /// <summary>
         /// Get xml document from <see cref="TestFile"/>.
         /// </summary>
         /// <returns>File data as xml document.</returns>
-        [Obsolete("Try not to use the file loader, please use the resource loader to ensure working of tests on all systems")]
-		protected virtual XmlDocument GetXMLDocFromFile()
+        [Obsolete("Try not to use the file loader, please use the resource loader to ensure working of tests on all systems")]
+        protected virtual XmlDocument GetXMLDocFromFile()
         {
             return GetXMLDocFromFile(TestFile);
         }
@@ -148,8 +167,8 @@ namespace Svg.UnitTests
         /// </summary>
         /// <param name="file">File to load.</param>
         /// <returns>File data as xml document.</returns>
-        [Obsolete("Try not to use the file loader, please use the resource loader to ensure working of tests on all systems")]
-		protected virtual XmlDocument GetXMLDocFromFile(string file)
+        [Obsolete("Try not to use the file loader, please use the resource loader to ensure working of tests on all systems")]
+        protected virtual XmlDocument GetXMLDocFromFile(string file)
         {
             if (!File.Exists(file))
                 Assert.Fail("Test file missing.", file);
@@ -157,9 +176,23 @@ namespace Svg.UnitTests
             var xmlDoc = new XmlDocument();
             xmlDoc.LoadXml(File.ReadAllText(file));
             return xmlDoc;
+        }
+
+        /// <summary>
+        /// Get the xml document from an input string
+        /// </summary>
+        /// <param name="input"></param>
+        /// <returns></returns>
+        protected virtual XmlDocument GetXMLDocFromString(string input)
+        {
+            Trace.WriteLine("Load XmlDocument from input data.");
+            var xmlDoc = new XmlDocument();
+            xmlDoc.XmlResolver = new SvgDtdResolver();
+            xmlDoc.LoadXml(input);
+            Trace.WriteLine("Done XmlDocument loading from resource data.");
+            return xmlDoc;
         }
 
-
         /// <summary>
         /// Get xml document from <see cref="TestResource"/>.
         /// </summary>
@@ -230,9 +263,9 @@ namespace Svg.UnitTests
         {
             using (var ms = new MemoryStream())
             {
-                img.Save(ms, ImageFormat.Png);
+                img.Save(ms, ImageFormat.Png);
                 ms.Flush();
-                Assert.IsTrue(ms.Length >= ExpectedSize, "Svg file does not match expected minimum size.");
+                Assert.IsTrue(ms.Length >= ExpectedSize, $"Svg file size {ms.Length} does not match expected minimum size (expected {ExpectedSize}).");
             }
         }
 
@@ -314,8 +347,8 @@ namespace Svg.UnitTests
             // Calculate percentage.
             int totalPixelCount = img1.Width * img1.Height;
             var imgDiffFactor = ((float)diffPixelCount / totalPixelCount);
-            imgEqualPercentage = imgDiffFactor * 100;
-            
+            imgEqualPercentage = imgDiffFactor * 100;
+
             return (imgDiffFactor == 1f);
         }
     }