diff --git a/contrib/check-code.py b/contrib/check-code.py
--- a/contrib/check-code.py
+++ b/contrib/check-code.py
@@ -74,6 +74,7 @@ testfilters = [
 uprefix = r"^  \$ "
 uprefixc = r"^  > "
 utestpats = [
+    (r'^(\S|  $ ).*(\S\s+|^\s+)\n', "trailing whitespace on non-output"),
     (uprefix + r'.*\|\s*sed', "use regex test output patterns instead of sed"),
     (uprefix + r'(true|exit 0)', "explicit zero exit unnecessary"),
     (uprefix + r'.*\$\?', "explicit exit code checks unnecessary"),
diff --git a/tests/test-convert-cvs-branch.t b/tests/test-convert-cvs-branch.t
--- a/tests/test-convert-cvs-branch.t
+++ b/tests/test-convert-cvs-branch.t
@@ -42,7 +42,7 @@ Branch the project
   $ cvscall up -r BRANCH > /dev/null
   cvs update: Updating .
 
-Modify file a, then b, then a 
+Modify file a, then b, then a
 
   $ sleep 1
   $ echo "2" > a
diff --git a/tests/test-push-warn.t b/tests/test-push-warn.t
--- a/tests/test-push-warn.t
+++ b/tests/test-push-warn.t
@@ -336,7 +336,7 @@ Using --new-branch to push new named bra
   added 1 changesets with 1 changes to 1 files
 
 
-Checking prepush logic does not allow silently pushing 
+Checking prepush logic does not allow silently pushing
 multiple new heads:
 
   $ cd ..
@@ -480,7 +480,7 @@ in the clone b1 is now the head of B
   $ hg ci -Ama2
   adding a2
 
-a2 is now the new branch head of A, and a new topological head 
+a2 is now the new branch head of A, and a new topological head
 it replaces a former inner branch head, so it should at most warn about
 A, not B
 
diff --git a/tests/test-rebase-mq-skip.t b/tests/test-rebase-mq-skip.t
--- a/tests/test-rebase-mq-skip.t
+++ b/tests/test-rebase-mq-skip.t
@@ -1,4 +1,4 @@
-This emulates the effects of an hg pull --rebase in which the remote repo 
+This emulates the effects of an hg pull --rebase in which the remote repo
 already has one local mq patch
 
   $ cat >> $HGRCPATH <<EOF