t/zfs: introduce ZNAPZENDTEST_ZFS_list_max_snapshots toggle [#691] (#691)

* t/zfs: introduce ZNAPZENDTEST_ZFS_list_max_snapshots toggle [#691]

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

* README.md: revise suggestion about remaining PID files [#691]

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

* README.md: further update the developer-oriented "make check" suggestions [#691]

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

* README.md, CHANGES: suggest how to run real programs with mock tools to debug failed tests [#691]

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

* README.md: suggest how to run tested perl programs with debug tracer [#691]

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

* Update check-spelling metadata for PR #691

Drop some more words check-spelling action deems unneeded;
add a few for this PR.

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>

---------

Signed-off-by: Jim Klimov <jimklimov+znapzend@gmail.com>
Co-authored-by: Jim Klimov <jimklimov+znapzend@gmail.com>
Co-authored-by: Tobias Oetiker <tobi@oetiker.ch>

Author: 3 people

.github/workflows/spelling/expect.txt

@@ -119,6 +119,7 @@ dstname
 DTIPS
 DTRT
 dummydataset
+ebug
 ebuild
 ecdsa
 eckels
@@ -207,10 +208,7 @@ installinfo
 Inztructionz
 ioloop
 Ip
-Ipath
-Ipictures
 irc
-Irecursive
 IRI
 isa
 isbn
@@ -361,6 +359,7 @@ propval
 Proxmox
 psgi
 pstcmd
+pwd
 QNX
 qq
 qw

CHANGES

@@ -1,6 +1,10 @@
 znapzend (0.23.3) UNRELEASED; urgency=medium
 
   * Revised CI recipes to pass on contributor forks #680 -- @jimklimov
+  * Introduced `ZNAPZENDTEST_ZFS_list_max_snapshots` in mock `t/zfs`
+    (default `58` for `dst`, as it was hard-coded since at least 2014,
+    adding `+2` more to `src` datasets), to speed up developer testing
+    iterations; updated the README.md with suggestions #691 -- @jimklimov
   * Revised `.gitignore` files, `Makefile.am` and Git tracked content
     to drop files (re-)generated during build from Git and so simplify
     life for developers; those generated files are directly added to

README.md

@@ -183,6 +183,49 @@ or
 > might behave differently. While that can happen in practice, that would be
 > a bug to report and pursue fixing.
 
+The tests use mocked tools under the `t` directory. Notably, the mock operation
+to `zfs list` generates a large listing of dataset snapshots (once a minute for
+an hour, by default), leading to significant test times like an hour or two!
+
+To speed up development iterations, when you just want to make sure no simple
+regressions were added, you can `export ZNAPZENDTEST_ZFS_list_max_snapshots=3`
+or so to significantly speed up the test suite.
+
+Also note that interrupted tests tend to leave the `znapzend*.pid` files in
+place (and corresponding daemons may remain running), so before re-running
+the tests you may want to follow up with `make clean-pidfiles` to kill any
+processes mentioned in those files (if present) and remove them.
+
+Combining the suggestions above, a relatively quick developer testing command
+(taking about 5 minutes for the full suite), optionally with a log file to
+later trawl for errors (if any), could look like this:
+
+```sh
+:; ZNAPZENDTEST_ZFS_list_max_snapshots=3 make clean-pidfiles check \
+    2>&1 | tee "test-make-check-`date +%s`.log"
+```
+
+To speed up development of tests (or to troubleshoot/debug any failures),
+you can also craft and execute individual test cases using the mock tools,
+by just preferring them in your `PATH`, e.g.:
+
+```sh
+:; PATH="`pwd`/t:$PATH" ./bin/znapzendzetup \
+    edit --donotask --tsformat=%Y%m%d-%H%M%S \
+    SRC "1h=>10min" tank/source \
+    DST:0 "1h=>10min" backup/destination
+```
+
+As usual with Perl programming, you can run the interpreter with one of the
+development/debugging modules enabled (may need to install some from CPAN
+or your OS packaging), e.g. `Devel::ebug` or `Devel::Trace`:
+
+```sh
+:; perl -d:Trace ./bin/znapzendzetup \
+    edit --donotask --recursive=on \
+    SRC tank/source
+```
+
 Packages
 --------
 

t/zfs

@@ -289,16 +289,22 @@ for ($command){
             print STDERR "failed to list mock dataset(s)\n";
             exit 1;
         }
-        if ($ARGV[4] && $ARGV[3] eq '-t' && $ARGV[4] eq 'snapshot'){
+        if ($ARGV[4] && $ARGV[3] eq '-t' && $ARGV[4] eq 'snapshot') {
             if ($ARGV[-1] =~ /^[^\@]+\@[^\@]+$/){
                 print $ARGV[-1] . "\n";
                 exit;
             }
             exit 1 if !exists $dataSets{$ARGV[-1]};
-            my $snapCount = ($dataSets{$ARGV[-1]} eq 'src') ? 60 : 58;
-            #get timestamp rounded to minutes
+            my $snapCount = envval('ZNAPZENDTEST_ZFS_list_max_snapshots');
+            if (!defined($snapCount) || $snapCount !~ /^\d+$/) {
+                $snapCount = 58; # +2 for src
+            }
+            if ($dataSets{$ARGV[-1]} eq 'src') {
+                $snapCount += 2;
+            }
+            # Get timestamp rounded to minutes
             my $time = localtime(int(time / 60) * 60 - 3600);
-            for (my $i = 0; $i < $snapCount; $i++){
+            for (my $i = 0; $i < $snapCount; $i++) {
                 print $ARGV[-1] . '@' . $time->strftime('%Y-%m-%d-%H%M%S') . "\n";
                 $time += 60;
             }