Re: [PATCH 1/4] qemu-iotests: allow passing unittest.main arguments to the test scripts

[Paolo Bonzini <pbonzini@redhat.com>]

On 23/03/21 17:56, Vladimir Sementsov-Ogievskiy wrote:
> hmm, just use a separate call of unittest.main, or honestly define a 
> varaible as Union[] or just Any ?

All the ugliness goes away if the implementation is done properly. :)

> For me normal try-finally is a lot more clean than calling atexit() in a 
> class method. It's just a strange interface. Prior to the patch user can 
> call execute_unittest several times and expect that output will be 
> printed during the call. After the patch outputs of all calls to 
> execute_unittest() will be printed at program exit..

Yeah, I agree.  I didn't like the finally, but I really didn't like it
because of the *behavior* of buffering the whole output.  I have changed
it to drop the buffering altogether, that's much better code and more usable:

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 90d0b62523..a74f4f9488 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -32,7 +32,7 @@
  import sys
  import time
  from typing import (Any, Callable, Dict, Iterable,
-                    List, Optional, Sequence, Tuple, TypeVar)
+                    List, Optional, Sequence, Tuple, Type, TypeVar)
  import unittest
  
  from contextlib import contextmanager
@@ -1271,37 +1271,49 @@ def func_wrapper(*args, **kwargs):
              return func(*args, **kwargs)
      return func_wrapper
  
+# We need to filter out the time taken from the output so that
+# qemu-iotest can reliably diff the results against master output,
+# and hide skipped tests from the reference output.
+
+class ReproducibleTestResult(unittest.TextTestResult):
+    def addSkip(self, test, reason):
+        # Same as TextTestResult, but print dot instead of "s"
+        unittest.TestResult.addSkip(self, test, reason)
+        if self.showAll:
+            self.stream.writeln("skipped {0!r}".format(reason))
+        elif self.dots:
+            self.stream.write(".")
+            self.stream.flush()
+
+class ReproducibleStreamWrapper(object):
+    def __init__(self, stream):
+        self.stream = stream
+
+    def __getattr__(self, attr):
+        if attr in ('stream', '__getstate__'):
+            raise AttributeError(attr)
+        return getattr(self.stream,attr)
+
+    def write(self, arg=None):
+        arg = re.sub(r'Ran (\d+) tests? in [\d.]+s', r'Ran \1 tests', arg)
+        arg = re.sub(r' \(skipped=\d+\)', r'', arg)
+        self.stream.write(arg)
+
+class ReproducibleTestRunner(unittest.TextTestRunner):
+    def __init__(self, stream: Optional[io.TextIOBase] = None,
+                 resultclass: Type = ReproducibleTestResult, *args, **kwargs):
+        rstream = ReproducibleStreamWrapper(stream or sys.stdout)
+        super().__init__(stream=rstream,           # type: ignore
+                         descriptions=True,
+                         resultclass=resultclass,
+                         *args, **kwargs)
+
  def execute_unittest(debug=False):
      """Executes unittests within the calling module."""
  
      verbosity = 2 if debug else 1
-
-    if debug:
-        output = sys.stdout
-    else:
-        # We need to filter out the time taken from the output so that
-        # qemu-iotest can reliably diff the results against master output.
-        output = io.StringIO()
-
-    runner = unittest.TextTestRunner(stream=output, descriptions=True,
-                                     verbosity=verbosity)
-    try:
-        # unittest.main() will use sys.exit(); so expect a SystemExit
-        # exception
-        unittest.main(testRunner=runner)
-    finally:
-        # We need to filter out the time taken from the output so that
-        # qemu-iotest can reliably diff the results against master output.
-        if not debug:
-            out = output.getvalue()
-            out = re.sub(r'Ran (\d+) tests? in [\d.]+s', r'Ran \1 tests', out)
-
-            # Hide skipped tests from the reference output
-            out = re.sub(r'OK \(skipped=\d+\)', 'OK', out)
-            out_first_line, out_rest = out.split('\n', 1)
-            out = out_first_line.replace('s', '.') + '\n' + out_rest
-
-            sys.stderr.write(out)
+    runner = unittest.ReproducibleTestRunner(verbosity=verbosity)
+    unittest.main(testRunner=ReproducibleTestRunner)
  
  def execute_setup_common(supported_fmts: Sequence[str] = (),
                           supported_platforms: Sequence[str] = (),