test: simple test for the checkpoint mechanism

Usage example:
  check/check.rb -C check/checkpoint /path/to/form

Unix is required and ParFORM is not supported for now. This regression
test ensures that future FORM enhancements will not break the checkpoint
mechanism, at least for some simple cases.

The following features are added to check.rb:
- Export FORM environment variable for tests. Note that it may contain
  spaces, e.g., FORM="tform -w4".
- Add unix?, which is (cygwin? || mac? || linux?).

Author: tueda

.github/workflows/test.yml

@@ -18,6 +18,8 @@ jobs:
           - {bin: form, test: default, timeout: 10}
           - {bin: tform, test: default, timeout: 10}
           - {bin: parform, test: default, timeout: 15}
+          - {bin: form, test: checkpoint, timeout: 10}
+          - {bin: tform, test: checkpoint, timeout: 10}
           - {bin: form, test: forcer, timeout: 60}
           - {bin: tform, test: forcer, timeout: 60}
     steps:

check/Makefile.am

@@ -27,9 +27,10 @@ endif
 TESTS += benchmark-fu.sh
 
 EXTRA_DIST = \
-	check-help.sh \
 	benchmark-fu.sh \
+	check-help.sh \
 	check.rb \
+	checkpoint/checkpoint.frm \
 	examples.frm \
 	features.frm \
 	fixes.frm \

check/check.rb

@@ -235,6 +235,10 @@ def linux?
     RUBY_PLATFORM =~ /linux/i
   end
 
+  def unix?
+    cygwin? || mac? || linux?
+  end
+
   def travis?
     ENV["TRAVIS"] == "true"
   end
@@ -307,6 +311,7 @@ def do_test(&block)
       @stderr = ""
       begin
         nfiles.times do |i|
+          ENV["FORM"] = FormTest.cfg.form_cmd
           @filename = "#{i + 1}.frm"
           execute("#{FormTest.cfg.form_cmd} #{@filename}")
           if !finished?

check/checkpoint/checkpoint.frm

@@ -0,0 +1,119 @@
+#ifndef `TEST'
+  #message Use -D TEST=XXX
+  #terminate
+#else
+  #include `NAME_' # `TEST'
+#endif
+.end
+
+*--#[ checkpoint_1 :
+* This program is intended to be executed 4 times, for example,
+*   form -D TEST=checkpoint_1 checkpoint.frm  # ok
+*   form -D TEST=checkpoint_1 checkpoint.frm  # fail
+*   form -D TEST=checkpoint_1 -R checkpoint.frm  # fail
+*   form -D TEST=checkpoint_1 -R checkpoint.frm  # ok
+* We check the result at the end of the program, by which we expect
+* possible deficits in snapshot/recovery would be detected.
+* Unix is required. ParFORM is not supported.
+#ifndef `N'
+  #define N "8"
+#endif
+
+#ifdef `QUIET'
+  Off stats;
+#endif
+
+#define StopThenContinueLockFilePrefix ".stc-"
+#define StopThenContinueCounter "0"
+
+#procedure StopThenContinue(?exitcode)
+  #ifdef `?exitcode'
+    #define exitcode "`?exitcode'"
+  #else
+    #define exitcode "-1"
+  #endif
+  #define counter "`StopThenContinueCounter++'"
+  #define lockfilename "`StopThenContinueLockFilePrefix'`counter'.tmp"
+* NOTE: for timestamps, the checkpoint feature uses TimeWallClock(),
+* which has only a centisecond precision. We may need some sleep
+* to guarantee that a snapshot file will be created (for low N,
+* in particular; though the wall clock value is supposed to increase
+* monotonically, I experienced cases where
+* TimeWallClock(1) - AC.CheckpointStamp == -1).
+* 0.05 seconds should be enough, but the POSIX sleep command assumes
+* an integral number as its argument; we fall back to 1 second when
+* it does not work.
+  #system sleep 0.05 2>/dev/null || sleep 1
+  .sort:StopThenContinue-`counter';
+  #system -e test -f `lockfilename'
+  #define error "`SYSTEMERROR_'"
+  #write <`lockfilename'> ""
+  #close <`lockfilename'>
+  #if `error'
+    #message Program intentionally stopped at `counter' (exitcode=`exitcode')
+    #terminate `?exitcode'
+  #endif
+  #remove <`lockfilename'>
+#endprocedure
+
+#procedure AssertEqual(expr1,expr2)
+  #$AssertEqualExpr1 = `expr1';
+  #$AssertEqualExpr2 = `expr2';
+  #$AssertEqualExpr3 = $AssertEqualExpr1 - $AssertEqualExpr2;
+  #$AssertEqualExpr1 = nterms_($AssertEqualExpr3);
+  #if `$AssertEqualExpr1' == 0
+    #message Assertion OK: `expr1' == `expr2'
+  #else
+    #message Assertion Failed: `expr1' == `expr2'
+    #terminate
+  #endif
+#endprocedure
+
+#call StopThenContinue(0)
+
+On checkpoint;
+Auto S x;
+L F = (x1+...+x15);
+L G = (x1+...+x15)^`N';
+#$n1 = 6;
+#$e1 = 1+x1+...+x15;
+#define a1 "20"
+.sort
+
+#call StopThenContinue()
+
+id x1 = x1 + x2 + x3 + x4 + x5;
+#$n2 = 7;
+#$e2 = x1+...+x15;
+#define a2 "21"
+.sort
+
+#call StopThenContinue()
+
+id x6 = -x1;
+id x7 = -x2;
+id x8 = -x3;
+id x9 = -x4;
+id x10 = -x5;
+id x11 = -x2;
+id x12 = -x3;
+id x13 = -x4;
+id x14 = -x5;
+#$e3 = $e1 - $e2;
+#message x15 -> {`$n1'*`$n2'-`a1'-`a2'+`$e3'}
+id x15 = {`$n1'*`$n2'-`a1'-`a2'+`$e3'};
+#ifndef `QUIET'
+  Print;
+#endif
+.sort
+#call AssertEqual(F,2)
+#call AssertEqual(G,{2^`N'})
+.end
+#system -e `FORM' 1.frm
+#system -e `FORM' -R 1.frm
+#system `FORM' -R 1.frm
+.end
+#require unix?
+#pend_if mpi? || valgrind?
+assert succeeded?
+*--#] checkpoint_1 :