gh-115720: Show number of leaks in huntrleaks progress reports (GH-115726)

Instead of showing a dot for each iteration, show:
- '.' for zero (on negative) leaks
- number of leaks for 1-9
- 'X' if there are more leaks

This allows more rapid iteration: when bisecting, I don't need
to wait for the final report to see if the test still leaks.

Also, show the full result if there are any non-zero entries.
This shows negative entries, for the unfortunate cases where
a reference is created and cleaned up in different runs.

Test *failure* is still determined by the existing heuristic.

3 files changed, 39 insertions, 14 deletions

diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
index 71a70af..f582c0d 100644
--- a/Lib/test/libregrtest/refleak.py
+++ b/Lib/test/libregrtest/refleak.py
@@ -88,9 +88,12 @@ def runtest_refleak(test_name, test_func,
     rc_before = alloc_before = fd_before = interned_before = 0
 
     if not quiet:
-        print("beginning", repcount, "repetitions", file=sys.stderr)
-        print(("1234567890"*(repcount//10 + 1))[:repcount], file=sys.stderr,
-              flush=True)
+        print("beginning", repcount, "repetitions. Showing number of leaks "
+                "(. for 0 or less, X for 10 or more)",
+              file=sys.stderr)
+        numbers = ("1234567890"*(repcount//10 + 1))[:repcount]
+        numbers = numbers[:warmups] + ':' + numbers[warmups:]
+        print(numbers, file=sys.stderr, flush=True)
 
     results = None
     dash_R_cleanup(fs, ps, pic, zdc, abcs)
@@ -116,13 +119,27 @@ def runtest_refleak(test_name, test_func,
         rc_after = gettotalrefcount() - interned_after * 2
         fd_after = fd_count()
 
-        if not quiet:
-            print('.', end='', file=sys.stderr, flush=True)
-
         rc_deltas[i] = get_pooled_int(rc_after - rc_before)
         alloc_deltas[i] = get_pooled_int(alloc_after - alloc_before)
         fd_deltas[i] = get_pooled_int(fd_after - fd_before)
 
+        if not quiet:
+            # use max, not sum, so total_leaks is one of the pooled ints
+            total_leaks = max(rc_deltas[i], alloc_deltas[i], fd_deltas[i])
+            if total_leaks <= 0:
+                symbol = '.'
+            elif total_leaks < 10:
+                symbol = (
+                    '.', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+                    )[total_leaks]
+            else:
+                symbol = 'X'
+            if i == warmups:
+                print(' ', end='', file=sys.stderr, flush=True)
+            print(symbol, end='', file=sys.stderr, flush=True)
+            del total_leaks
+            del symbol
+
         alloc_before = alloc_after
         rc_before = rc_after
         fd_before = fd_after
@@ -158,14 +175,20 @@ def runtest_refleak(test_name, test_func,
     ]:
         # ignore warmup runs
         deltas = deltas[warmups:]
-        if checker(deltas):
+        failing = checker(deltas)
+        suspicious = any(deltas)
+        if failing or suspicious:
             msg = '%s leaked %s %s, sum=%s' % (
                 test_name, deltas, item_name, sum(deltas))
-            print(msg, file=sys.stderr, flush=True)
-            with open(filename, "a", encoding="utf-8") as refrep:
-                print(msg, file=refrep)
-                refrep.flush()
-            failed = True
+            print(msg, end='', file=sys.stderr)
+            if failing:
+                print(file=sys.stderr, flush=True)
+                with open(filename, "a", encoding="utf-8") as refrep:
+                    print(msg, file=refrep)
+                    refrep.flush()
+                failed = True
+            else:
+                print(' (this is fine)', file=sys.stderr, flush=True)
     return (failed, results)
 
 
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index b80e052..7e1eaa7 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -1171,8 +1171,8 @@ class ArgsTestCase(BaseTestCase):
                                 stderr=subprocess.STDOUT)
         self.check_executed_tests(output, [test], failed=test, stats=1)
 
-        line = 'beginning 6 repetitions\n123456\n......\n'
-        self.check_line(output, re.escape(line))
+        line = r'beginning 6 repetitions. .*\n123:456\n[.0-9X]{3} 111\n'
+        self.check_line(output, line)
 
         line2 = '%s leaked [1, 1, 1] %s, sum=3\n' % (test, what)
         self.assertIn(line2, output)
diff --git a/Misc/NEWS.d/next/Tests/2024-02-20-15-47-41.gh-issue-115720.w8i8UG.rst b/Misc/NEWS.d/next/Tests/2024-02-20-15-47-41.gh-issue-115720.w8i8UG.rst
new file mode 100644
index 0000000..a03ee11
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2024-02-20-15-47-41.gh-issue-115720.w8i8UG.rst
@@ -0,0 +1,2 @@
+Leak tests (``-R``, ``--huntrleaks``) now show a summary of the number of
+leaks found in each iteration.