Added --update-check option to partest.

automatically update all the checkfiles with whatever output the tests
are producing. I suppose it goes without saying that this would be easy
to misuse, so let the record show that I accept no responsibility when
someone overwrites all the checkfiles in trunk with their shopping list
and checks it in.

Recommended usage: See some tests fail.  Run

  partest --failed --show-diff

Verify that all output differs in the expected fashion. Then run

  partest --failed --update-check

Mission accomplished.  No review.

2 files changed, 15 insertions, 10 deletions

diff --git a/src/partest/scala/tools/partest/Actions.scala b/src/partest/scala/tools/partest/Actions.scala
index 3e745714cb..48b80cface 100644
--- a/src/partest/scala/tools/partest/Actions.scala
+++ b/src/partest/scala/tools/partest/Actions.scala
@@ -136,7 +136,7 @@ trait Actions {
 
     /** The default cleanup normalizes paths relative to sourcesDir.
      */
-    def diffCleanup(f: File) = safeLines(f) map normalizePaths mkString "\n"
+    def diffCleanup(f: File) = safeLines(f) map normalizePaths mkString ("", "\n", "\n")
 
     /** If optional is true, a missing check file is considered
      *  a successful diff.  Necessary since many categories use
@@ -146,19 +146,23 @@ trait Actions {
       def arg1    = tracePath(check)
       def arg2    = tracePath(log)
       def noCheck = !check.exists && returning(true)(_ =>  trace("diff %s %s [unchecked]".format(arg1, arg2)))
+      def output  = diffCleanup(log)
+      def matches = safeSlurp(check).trim == output.trim
+
+      def traceMsg =
+        if (isDryRun) "diff %s %s".format(arg1, arg2)
+        else "diff %s %s [%s]".format(arg1, arg2, (if (matches) "passed" else "failed"))
 
       noCheck || {
-        def result  = safeSlurp(check).trim == diffCleanup(log).trim
-        def msg     = if (result) "passed" else "failed"
+        trace(traceMsg)
 
-        if (isDryRun) {
-          trace("diff %s %s".format(arg1, arg2))
+        isDryRun || matches || (isUpdateCheck && {
+          normal("** diff %s %s failed:\n".format(arg1, arg2))
+          normal(diffOutput())
+          normal("** updating %s and marking as passed.\n".format(arg1))
+          check writeAll output
           true
-        }
-        else {
-          trace("diff %s %s [%s]".format(arg1, arg2, msg))
-          result
-        }
+        })
       }
     }
 
diff --git a/src/partest/scala/tools/partest/PartestSpec.scala b/src/partest/scala/tools/partest/PartestSpec.scala
index e4259d70be..50c82fb783 100644
--- a/src/partest/scala/tools/partest/PartestSpec.scala
+++ b/src/partest/scala/tools/partest/PartestSpec.scala
@@ -77,6 +77,7 @@ trait PartestSpec extends Spec with Meta.StdOpts with Interpolation {
   val isNoCleanup   = "nocleanup"     / "do not delete any logfiles or object dirs" --?
   val isStats       = "stats"         / "collect and print statistics about the tests" --?
   val isValidate    = "validate"      / "examine test filesystem for inconsistencies" --?
+  val isUpdateCheck = "update-check"  / "overwrite checkFile if diff fails" --?
 
                       "version"       / "print version"   --> runAndExit(println(Properties.versionMsg))