added proper error message when trying to partition a dataset by non-existent key; added test case and some documentation

git-svn-id: https://asterixdb.googlecode.com/svn/branches/asterix_stabilization@1246 eaa15691-b419-025a-1212-ee371bd00084
diff --git a/asterix-app/src/test/resources/runtimets/testsuite.xml b/asterix-app/src/test/resources/runtimets/testsuite.xml
index de694cd..e8e7d72 100644
--- a/asterix-app/src/test/resources/runtimets/testsuite.xml
+++ b/asterix-app/src/test/resources/runtimets/testsuite.xml
@@ -1963,6 +1963,12 @@
     </test-case>
   </test-group>
   <test-group name="misc">
+  <test-case FilePath="misc">
+      <compilation-unit name="partition-by-nonexistent-field">
+        <output-file compare="Text">partition-by-nonexistent-field.adm</output-file>
+        <expected-error>edu.uci.ics.asterix.common.exceptions.AsterixException</expected-error>
+      </compilation-unit>
+    </test-case>
     <test-case FilePath="misc">
       <compilation-unit name="float_01">
         <output-file compare="Text">float_01.adm</output-file>