bpo-36725: regrtest: add TestResult type (GH-12960)

* Add TestResult and MultiprocessResult types to ensure that results
  always have the same fields.
* runtest() now handles KeyboardInterrupt
* accumulate_result() and format_test_result() now takes a TestResult
* cleanup_test_droppings() is now called by runtest() and mark the
  test as ENV_CHANGED if the test leaks support.TESTFN file.
* runtest() now includes code "around" the test in the test timing
* Add print_warning() in test.libregrtest.utils to standardize how
  libregrtest logs warnings to ease parsing the test output.
* support.unload() is now called with abstest rather than test_name
* Rename 'test' variable/parameter to 'test_name'
* dash_R(): remove unused the_module parameter
* Remove unused imports

1 files changed, 6 insertions, 1 deletions

diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index d36bf91966..fb9971a64f 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -1,5 +1,6 @@
-import os.path
 import math
+import os.path
+import sys
 import textwrap
 
 
@@ -54,3 +55,7 @@ def printlist(x, width=70, indent=4, file=None):
     print(textwrap.fill(' '.join(str(elt) for elt in sorted(x)), width,
                         initial_indent=blanks, subsequent_indent=blanks),
           file=file)
+
+
+def print_warning(msg):
+    print(f"Warning -- {msg}", file=sys.stderr, flush=True)