patch 8.2.1432: various inconsistencies in test files

Problem:    Various inconsistencies in test files.
Solution:   Add modelines where they were missing.  Use Check commands instead
            of silently skipping over tests.  Adjust indents and comments.
            (Ken Takata, closes #6695)
diff --git a/src/testdir/test_behave.vim b/src/testdir/test_behave.vim
index c26bfe7..72411b4 100644
--- a/src/testdir/test_behave.vim
+++ b/src/testdir/test_behave.vim
@@ -27,3 +27,5 @@
 func Test_behave_error()
   call assert_fails('behave x', 'E475:')
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab