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.

4 files changed, 67 insertions, 53 deletions

diff --git a/tests/tail-2/F-vs-rename b/tests/tail-2/F-vs-rename
index 38a1b3f40..74db80137 100755
--- a/tests/tail-2/F-vs-rename
+++ b/tests/tail-2/F-vs-rename
@@ -42,36 +42,36 @@ mv a b || fail=1
 until grep inaccessible out >/dev/null 2>&1; do :; done
 
 echo x > a
-# Wait up to 4s for this to appear in the output:
+# Wait up to 6.3s for this to appear in the output:
 # "tail: `...' has appeared;  following end of new file"
-found=false
-for i in $(seq 20); do
-  grep 'has appeared;' out > /dev/null && { found=true; break; }
-  sleep .2
-done
-$found || { echo "$0: a: unexpected delay?"; cat out; fail=1; }
+tail_f_vs_rename_1()
+{
+  local delay="$1"
+  grep 'has appeared;' out > /dev/null ||
+    { sleep $delay; return 1; }
+}
+retry_delay_ tail_f_vs_rename_1 .1 7 ||
+  { echo "$0: a: unexpected delay?"; cat out; fail=1; }
 
 echo y >> b
-# Wait up to 4s for "y" to appear in the output:
-found=false
-for i in $(seq 20); do
-  case $(tr '\n' @ < out) in
-    *'@@==> b <==@y@') found=true; break 2;;
-  esac
-  sleep .2
-done
-$found || { echo "$0: b: unexpected delay?"; cat out; fail=1; }
+# Wait up to 6.3s for "y" to appear in the output:
+tail_f_vs_rename_2() {
+  local delay="$1"
+  tr '\n' @ < out | grep '@@==> b <==@y@$' > /dev/null ||
+    { sleep $delay; return 1; }
+}
+retry_delay_ tail_f_vs_rename_2 .1 7 ||
+  { echo "$0: b: unexpected delay?"; cat out; fail=1; }
 
 echo z >> a
-# Wait up to 4s for "z" to appear in the output:
-found=false
-for i in $(seq 20); do
-  case $(tr '\n' @ < out) in
-    *'@@==> a <==@z@') found=true; break 2;;
-  esac
-  sleep .2
-done
-$found || { echo "$0: b: unexpected delay?"; cat out; fail=1; }
+# Wait up to 6.3s for "z" to appear in the output:
+tail_f_vs_rename_3() {
+  local delay="$1"
+  tr '\n' @ < out | grep '@@==> a <==@z@$' > /dev/null ||
+    { sleep $delay; return 1; }
+}
+retry_delay_ tail_f_vs_rename_3 .1 7 ||
+  { echo "$0: a: unexpected delay?"; cat out; fail=1; }
 
 kill -HUP $pid
 
diff --git a/tests/tail-2/flush-initial b/tests/tail-2/flush-initial
index cf5438011..98de2e1f5 100755
--- a/tests/tail-2/flush-initial
+++ b/tests/tail-2/flush-initial
@@ -29,14 +29,15 @@ echo line > in || fail=1
 tail -f in > out &
 tail_pid=$!
 
-# Wait for 1 second for the file to be flushed.
-for i in $(seq 10); do
-  test -s out && break
-  echo sleep .1s
-  sleep .1
-done
-
-test -s out || fail=1
+# Wait for 1.5s for the file to be flushed.
+tail_flush()
+{
+  local delay="$1"
+
+  test -s out ||
+    { sleep "$delay"; return 1; }
+}
+retry_delay_ tail_flush .1 5 || fail=1
 
 kill $tail_pid
 
diff --git a/tests/tail-2/tail-n0f b/tests/tail-2/tail-n0f
index 0ff3a3d01..6a9b59c37 100755
--- a/tests/tail-2/tail-n0f
+++ b/tests/tail-2/tail-n0f
@@ -39,12 +39,18 @@ for inotify in ---disable-inotify ''; do
     for c_or_n in c n; do
       tail --sleep=4 -${c_or_n} 0 -f $inotify $file &
       pid=$!
-      sleep .5
-      state=$(get_process_status_ $pid)
-      case $state in
-        S*) ;;
-        *) echo $0: process in unexpected state: $state 1>&2; fail=1 ;;
-      esac
+      tail_sleeping()
+      {
+        local delay="$1"; sleep $delay
+        state=$(get_process_status_ $pid)
+        case $state in
+          S*) ;;
+          *) return 1;;
+        esac
+      }
+      # Wait up to 1.5s for tail to sleep
+      retry_delay_ tail_sleeping .1 4 ||
+        { echo $0: process in unexpected state: $state >&2; fail=1; }
       kill $pid
     done
   done
diff --git a/tests/tail-2/wait b/tests/tail-2/wait
index 5c9eff0a2..332cfcc09 100755
--- a/tests/tail-2/wait
+++ b/tests/tail-2/wait
@@ -25,7 +25,6 @@ fi
 . $srcdir/test-lib.sh
 
 touch here || framework_failure
-touch k || framework_failure
 { touch unreadable && chmod a-r unreadable; } || framework_failure
 
 
@@ -59,19 +58,27 @@ for inotify in ---disable-inotify ''; do
   test -s tail.err && fail=1
   :>tail.err
 
-
-  tail -s.1 --max-unchanged-stats=2 -F $inotify k > tail.out &
-  pid=$!
-  sleep .5
-  mv k l
-  sleep .5
-  touch k
-  mv k l
-  sleep .5
-  echo NO >> l
-  sleep .5
-  kill $pid
-  test -s tail.out && fail=1
+  tail_F()
+  {
+    local delay="$1"
+
+    touch k || framework_failure
+    tail -s.1 --max-unchanged-stats=2 -F $inotify k > tail.out &
+    pid=$!
+    sleep $delay
+    mv k l
+    sleep $delay
+    touch k
+    mv k l
+    sleep $delay
+    echo NO >> l
+    sleep $delay
+    kill $pid
+    rm -f k l
+
+    test ! -s tail.out
+  }
+  retry_delay_ tail_F .1 4 || fail=1
 done
 
 Exit $fail