bpo-33873: Backport regrtest from master to 3.7 (GH-7935) (GH-7937)

* bpo-33718: regrtest: use format_duration() to display failed tests (GH-7686)

* Enhance also format_duration(): work on integers and rounds towards
  +infinity (math.ceil).
* Write unit tests on format_duration()

(cherry picked from commit 4ffe9c2b251f6e027b26250b7a2618e78d4edd22)

* bpo-33873: regrtest: Add warning on -R 1:3 (GH-7736)

regrtest: Add warning when using less than 3 warmup runs like -R 1:3.
(cherry picked from commit cac4fef8860e66a9da67d09762f5b614b9471a12)

* bpo-33873: Fix bug in `runtest.py` and add checks for invalid `-R` parameters (GH-7735)

Fix bug in `Lib/test/libregrtest/runtest.py` that makes running tests an extra time than the specified number of runs.

Add check for invalid --huntrleaks/-R parameters.

(cherry picked from commit 58ed7307ea0b5c5aa052291ebc3030f314f938d8)
(cherry picked from commit d1f9481b7a2d31c40fca1347ef99d819eb656ce7)

1 files changed, 18 insertions, 9 deletions

diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index 85049cb06b..d36bf91966 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -1,19 +1,28 @@
 import os.path
+import math
 import textwrap
 
 
 def format_duration(seconds):
-    if seconds < 1.0:
-        return '%.0f ms' % (seconds * 1e3)
-    if seconds < 60.0:
-        return '%.0f sec' % seconds
+    ms = math.ceil(seconds * 1e3)
+    seconds, ms = divmod(ms, 1000)
+    minutes, seconds = divmod(seconds, 60)
+    hours, minutes = divmod(minutes, 60)
 
-    minutes, seconds = divmod(seconds, 60.0)
-    hours, minutes = divmod(minutes, 60.0)
+    parts = []
     if hours:
-        return '%.0f hour %.0f min' % (hours, minutes)
-    else:
-        return '%.0f min %.0f sec' % (minutes, seconds)
+        parts.append('%s hour' % hours)
+    if minutes:
+        parts.append('%s min' % minutes)
+    if seconds:
+        parts.append('%s sec' % seconds)
+    if ms:
+        parts.append('%s ms' % ms)
+    if not parts:
+        return '0 ms'
+
+    parts = parts[:2]
+    return ' '.join(parts)
 
 
 def removepy(names):