Move generated files to gen/.

tool/test.sh

 #!/bin/bash
 set -e # bail on error
 
 function fail {
   echo -e "Some tests failed"
   return 1
 }
 
 # Some tests require being run from the package root
 # switch to the root directory of dev_compiler
 cd $( dirname "${BASH_SOURCE[0]}" )/..
 
 # Check minimum SDK version
 ./tool/sdk_version_check.dart 1.9.0-dev.4.0 || fail
 
 # Delete codegen expectation files to be sure that if a test fails to compile
 # we don't erroneously pick up the old version.
 if [ -d test/codegen/expect ]; then
   rm -r test/codegen/expect || fail
 fi
 
+if [ -d gen/codegen_input ]; then
+  rm -r gen/codegen_input || fail
+fi
+
+if [ -d gen/codegen_output ]; then
+  rm -r gen/codegen_output || fail
+fi
+
 # Make sure we don't run tests in code coverage mode.
 # this will cause us to generate files that are not part of the baseline
 # TODO(jmesserly): we should move diff into Dart code, so we don't need to
 # worry about this. Also if we're in code coverage mode, we should avoid running
 # all_tests twice. Finally self_host_test is not currently being tracked by
 # code coverage.
 unset COVERALLS_TOKEN
 pub run test:test test/all_tests.dart || fail
 
 {
   fc=`find test -name "*.dart" |\
       xargs grep "/\*\S* should be \S*\*/" | wc -l`
   echo "There are" $fc "tests marked as known failures."
 }
 
 echo -e "All tests pass"