tests: make tests requiring a delay to pass, more robust

* tests/init.cfg: Introduce a retry_delay_() function to
repeatedly call a test function that requires a delay.
This delay can now be shorter for the common case on fast
systems, but will double until a configurable limit it reached
before failing on slower systems.
* tests/dd/reblock: Use retry_delay_.
* tests/misc/cat-buf: Likewise.
* tests/misc/stdbuf: Likewise.
* tests/tail-2/F-vs-rename: Likewise.
* tests/tail-2/flush-initial: Likewise.
* tests/tail-2/tail-n0f: Likewise.
* tests/tail-2/wait: Likewise.
* test/dd/misc: Comment that delay is needed to trigger failure.

1 files changed, 38 insertions, 17 deletions

diff --git a/tests/misc/stdbuf b/tests/misc/stdbuf
index 0e94ae21e..5822698ea 100755
--- a/tests/misc/stdbuf
+++ b/tests/misc/stdbuf
@@ -59,18 +59,32 @@ stdbuf -o1 no_such # no such command
 test $? = 127 || fail=1
 
 # Ensure line buffering stdout takes effect
-printf '1\n' > exp
-dd count=1 if=fifo > out 2> err &
-(printf '1\n'; sleep .2; printf '2\n') | stdbuf -oL uniq > fifo
-wait # for dd to complete
-compare out exp || fail=1
-
-# Ensure un buffering stdout takes effect
-printf '1\n' > exp
-dd count=1 if=fifo > out 2> err &
-(printf '1\n'; sleep .2; printf '2\n') | stdbuf -o0 uniq > fifo
-wait # for dd to complete
-compare out exp || fail=1
+stdbuf_linebuffer()
+{
+  local delay="$1"
+
+  printf '1\n' > exp
+  dd count=1 if=fifo > out 2> err &
+  (printf '1\n'; sleep $delay; printf '2\n') | stdbuf -oL uniq > fifo
+  wait # for dd to complete
+  compare out exp
+}
+
+retry_delay_ stdbuf_linebuffer .1 6 || fail=1
+
+stdbuf_unbuffer()
+{
+  local delay="$1"
+
+  # Ensure un buffering stdout takes effect
+  printf '1\n' > exp
+  dd count=1 if=fifo > out 2> err &
+  (printf '1\n'; sleep $delay; printf '2\n') | stdbuf -o0 uniq > fifo
+  wait # for dd to complete
+  compare out exp
+}
+
+retry_delay_ stdbuf_unbuffer .1 6 || fail=1
 
 # Ensure un buffering stdin takes effect
 #  The following works for me, but is racy. I.E. we're depending
@@ -93,10 +107,17 @@ compare out exp || fail=1
 # Ensure block buffering stdout takes effect
 # We don't currently test block buffering failures as
 # this doesn't work on on GLIBC-2.7 or GLIBC-2.9 at least.
-   # printf '1\n2\n' > exp
-   # dd count=1 if=fifo > out 2> err &
-   # (printf '1\n'; sleep .2; printf '2\n') | stdbuf -o4 uniq > fifo
-   # wait # for dd to complete
-   # compare out exp || fail=1
+   # stdbuf_blockbuffer()
+   # {
+   #   local delay="$1"
+   #
+   #   printf '1\n2\n' > exp
+   #   dd count=1 if=fifo > out 2> err &
+   #   (printf '1\n'; sleep $delay; printf '2\n') | stdbuf -o4 uniq > fifo
+   #   wait # for dd to complete
+   #   compare out exp
+   # }
+   #
+   # retry_delay_ stdbuf_blockbuffer .1 6 || fail=1
 
 Exit $fail