Fix failing C# tests

As a result of a mono upgrade, tests on non windows platform would fail
due to a warning.
This fix removes the warning by providing compatibility information as
part of the build.
HashSet was also renamed to a clean name.

runtime/CSharp/Antlr4.Runtime/Sharpen/Compat/HashSet.cs

@@ -26,8 +26,7 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-#if !NET35PLUS || COMPACT
-
+#if FALSE
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -803,4 +802,4 @@ namespace Antlr4.Runtime.Sharpen {
 	}
 }
 
-#endif
+#endif

runtime/CSharp/Antlr4.mono.sln

@@ -43,9 +43,6 @@ Global
 	GlobalSection(NestedProjects) = preSolution
 		{4CE79A54-058D-4940-875E-7F6AA9922A7D} = {47C0086D-577C-43DA-ADC7-544F27656E45}
 	EndGlobalSection
-	GlobalSection(MonoDevelopProperties) = preSolution
-		StartupItem = Antlr4.Runtime\Antlr4.Runtime.mono.csproj
-	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection

tool/test/org/antlr/v4/test/rt/csharp/Antlr4.Test.mono.csproj

@@ -1,4 +1,5 @@
-<?xml version="1.0" encoding="UTF-8"?><Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Build" ToolsVersion="4.0">
+<?xml version="1.0" encoding="UTF-8"?>
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Build" ToolsVersion="4.0">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
@@ -41,4 +42,10 @@
       <Name>Antlr4.Runtime.mono</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <None Include="App.config">
+      <LogicalName>Test.exe.config</LogicalName>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
 </Project>

tool/test/org/antlr/v4/test/rt/csharp/App.config

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<configuration>
+   <startup>
+      <supportedRuntime version="v2.0.50727"/>
+      <supportedRuntime version="v4.0"/>
+   </startup>
+</configuration>

tool/test/org/antlr/v4/test/rt/csharp/BaseTest.java

@@ -56,8 +56,10 @@ import javax.xml.transform.stream.StreamResult;
 import javax.xml.xpath.XPathConstants;
 import javax.xml.xpath.XPathExpression;
 import javax.xml.xpath.XPathFactory;
+
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -447,17 +449,12 @@ public abstract class BaseTest {
 	public boolean createProject() {
 		try {
 			String pack = this.getClass().getPackage().getName().replace(".", "/") + "/";
-			// save AssemblyInfo
-			InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream(pack + "AssemblyInfo.cs");
-			OutputStream output = new FileOutputStream(new File(tmpdir, "AssemblyInfo.cs").getAbsolutePath());
-			while(input.available()>0) {
-				output.write(input.read());
-			}
-			output.close();
-			input.close();
+			// save auxiliary files
+			saveResourceAsFile(pack + "AssemblyInfo.cs", new File(tmpdir, "AssemblyInfo.cs"));
+			saveResourceAsFile(pack + "App.config", new File(tmpdir, "App.config"));
 			// update project
 			String projectName = isWindows() ? "Antlr4.Test.vs2013.csproj" : "Antlr4.Test.mono.csproj";
-			input = Thread.currentThread().getContextClassLoader().getResourceAsStream(pack + projectName);
+			InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream(pack + projectName);
 			Document prjXml = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(input);
 			// update runtime project reference
 			String runtimePath = System.getProperty("antlr-csharp-runtime-project");
@@ -498,6 +495,16 @@ public abstract class BaseTest {
 		}
 	}
 
+	private void saveResourceAsFile(String resourceName, File file) throws IOException {
+		InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream(resourceName);
+		OutputStream output = new FileOutputStream(file.getAbsolutePath());
+		while(input.available()>0) {
+			output.write(input.read());
+		}
+		output.close();
+		input.close();
+	}
+
 	public String execTest() {
 		try {
 			String exec = locateExec();