(GH-400) Fix Path environment parsing for Ruby Helper

Previously the RubyHelper manipulates the path environment however due to Object
property names being case sensitive it could simply be that it's called Path or
path, particularly on Windows not so much on Linux etc.. It's also possible that
there is no PATH set but unlikely.

This commit changes the Path processing be to case-insensitive and force it to
be called PATH

This commit also removes environment variables whose value is set to null or
undefined.

Author: glennsarti

src/rubyHelper.ts

@@ -30,7 +30,20 @@ export class RubyHelper {
         break;
     }
 
-    if (spawn_options.env.PATH === undefined) { spawn_options.env.PATH = ''; }
+    if (spawn_options.env.PATH === undefined) {
+      // It's possible that there is no PATH set but unlikely. Due to Object property names being
+      // case sensitive it could simply be that it's called Path or path, particularly on Windows
+      // not so much on Linux etc.. Look through all of the environment names looking for PATH in a
+      // case insensitive way and remove the conflicting env var.
+      let envPath: string = '';
+      Object.keys(spawn_options.env).forEach(function(keyname) {
+        if (keyname.match(/^PATH$/i)) {
+          envPath = spawn_options.env[keyname];
+          spawn_options.env[keyname] = undefined;
+        }
+      });
+      spawn_options.env.PATH = envPath;
+    }
     if (spawn_options.env.RUBYLIB === undefined) { spawn_options.env.RUBYLIB = ''; }
 
     let command = '';
@@ -68,14 +81,27 @@ export class RubyHelper {
     logger.debug(logPrefix + 'Using environment variable GEM_PATH='      + spawn_options.env.GEM_PATH);
     logger.debug(logPrefix + 'Using environment variable GEM_HOME='      + spawn_options.env.GEM_HOME);
 
+    // undefined or null values still appear in the child spawn environment variables
+    // In this case these elements should be removed from the Object
+    this.removeEmptyElements(spawn_options.env);
+
     let result = {
       command: command,
       args   : [rubyFile],
       options: spawn_options
     };
 
     return result;
+  }
 
+  private static removeEmptyElements(obj: Object) {
+    const propNames = Object.getOwnPropertyNames(obj);
+    for (var i = 0; i < propNames.length; i++) {
+      const propName = propNames[i];
+      if (obj[propName] === null || obj[propName] === undefined) {
+        delete obj[propName];
+      }
+    }
   }
 
   private static shallowCloneObject(value:Object): Object {