Fix falsely passing PowerShellVersionTests

This change fixes the current PowerShellVersionTests to use an absolute
path to the version-specific PowerShell reference assembly.  The relative
path which was being used somehow caused MSBuild to use the in-box
PowerShell v5 assemblies since the HintPath couldn't be found.  This
caused the tests for PowerShell 3 and 4 to pass even though they should be
failing.

This change also includes some fixes to existing code that is incompatible
with PowerShell 3 and 4.

Author: daviwil

src/PowerShellEditorServices/Language/AstOperations.cs

@@ -180,18 +180,24 @@ static public SymbolReference FindDefinitionOfSymbol(
         /// <returns>A collection of SymbolReference objects</returns>
         static public IEnumerable<SymbolReference> FindSymbolsInDocument(Ast scriptAst, Version powerShellVersion)
         {
+            IEnumerable<SymbolReference> symbolReferences = null;
+
             if (powerShellVersion >= new Version(5,0))
             {
+#if PowerShellv5
                 FindSymbolsVisitor2 findSymbolsVisitor = new FindSymbolsVisitor2();
                 scriptAst.Visit(findSymbolsVisitor);
-                return findSymbolsVisitor.SymbolReferences;
+                symbolReferences = findSymbolsVisitor.SymbolReferences;
+#endif
             }
             else
             {
                 FindSymbolsVisitor findSymbolsVisitor = new FindSymbolsVisitor();
                 scriptAst.Visit(findSymbolsVisitor);
-                return findSymbolsVisitor.SymbolReferences;
+                symbolReferences = findSymbolsVisitor.SymbolReferences;
             }
+
+            return symbolReferences;
         }
 
         /// <summary>

src/PowerShellEditorServices/Language/FindSymbolsVisitor2.cs

@@ -3,6 +3,7 @@
 
 namespace Microsoft.PowerShell.EditorServices
 {
+#if PowerShellv5
     /// <summary>
     /// The visitor used to find all the symbols (function and class defs) in the AST. 
     /// </summary>
@@ -67,4 +68,5 @@ public override AstVisitAction VisitConfigurationDefinition(ConfigurationDefinit
             return AstVisitAction.Continue;
         }
     }
+#endif
 }

test/PowerShellEditorServices.Test/Language/PowerShellVersionTests.cs

@@ -16,7 +16,12 @@ public class PowerShellVersionTests
         [InlineData("5")]
         public void CompilesWithPowerShellVersion(string version)
         {
-            var assemblyPath = string.Format(@"..\..\..\..\packages\Microsoft.PowerShell.{0}.ReferenceAssemblies.1.0.0\lib\net4\System.Management.Automation.dll", version);
+            var assemblyPath = 
+                Path.GetFullPath(
+                    string.Format(
+                        @"..\..\..\..\packages\Microsoft.PowerShell.{0}.ReferenceAssemblies.1.0.0\lib\net4\System.Management.Automation.dll", 
+                        version));
+
             var projectPath = @"..\..\..\..\src\PowerShellEditorServices\PowerShellEditorServices.csproj";
             FileInfo fi = new FileInfo(projectPath);
             var projectVersion = Path.Combine(fi.DirectoryName, version + ".PowerShellEditorServices.csproj");