mtest: introduce TestLogger

The TestLogger class lets us move the code for all those log files
out of TestHarness.  The interface is based on JunitBuilder, which
is converted already in this commit.  Over the next commits, we
will also convert JSON, text and console output.

The main difference with JunitBuilder is that the completion method is
asynchronous.  This can be useful if the logger needs to clean up after
itself and wait for asyncio tasks.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

mesonbuild/mtest.py

@@ -354,7 +354,21 @@ class TAPParser:
                 yield self.Error('Too many tests run (expected {}, got {})'.format(plan.count, num_tests))
 
 
-class JunitBuilder:
+class TestLogger:
+    def start(self, harness: 'TestHarness') -> None:
+        pass
+
+    def log(self, harness: 'TestHarness', result: 'TestRun') -> None:
+        pass
+
+    async def finish(self, harness: 'TestHarness') -> None:
+        pass
+
+    def close(self) -> None:
+        pass
+
+
+class JunitBuilder(TestLogger):
 
     """Builder for Junit test results.
 
@@ -377,7 +391,7 @@ class JunitBuilder:
             'testsuites', tests='0', errors='0', failures='0')
         self.suites = {}  # type: T.Dict[str, et.Element]
 
-    def log(self, test: 'TestRun') -> None:
+    def log(self, harness: 'TestHarness', test: 'TestRun') -> None:
         """Log a single test case."""
         if test.junit is not None:
             for suite in test.junit.findall('.//testsuite'):
@@ -461,7 +475,7 @@ class JunitBuilder:
                 err = et.SubElement(testcase, 'system-err')
                 err.text = test.stde.rstrip()
 
-    def write(self) -> None:
+    async def finish(self, harness: 'TestHarness') -> None:
         """Calculate total test counts and write out the xml result."""
         for suite in self.suites.values():
             self.root.append(suite)
@@ -911,7 +925,7 @@ class TestHarness:
         self.logfilename = None   # type: T.Optional[str]
         self.logfile = None       # type: T.Optional[T.TextIO]
         self.jsonlogfile = None   # type: T.Optional[T.TextIO]
-        self.junit = None         # type: T.Optional[JunitBuilder]
+        self.loggers = []         # type: T.List[TestLogger]
 
         if self.options.benchmark:
             self.tests = load_benchmarks(options.wd)
@@ -935,6 +949,8 @@ class TestHarness:
             if lfile:
                 lfile.close()
                 setattr(self, f, None)
+        for l in self.loggers:
+            l.close()
 
     def merge_suite_options(self, options: argparse.Namespace, test: TestSerialisation) -> T.Dict[str, str]:
         if ':' in options.setup:
@@ -1014,8 +1030,8 @@ class TestHarness:
             self.logfile.write("\n\n" + result.get_log() + "\n")
         if self.jsonlogfile:
             write_json_log(self.jsonlogfile, result)
-        if self.junit:
-            self.junit.log(result)
+        for l in self.loggers:
+            l.log(self, result)
 
     def print_summary(self) -> None:
         # Prepend a list of failures
@@ -1042,9 +1058,6 @@ class TestHarness:
         if self.logfile:
             self.logfile.write(msg)
 
-        if self.junit:
-            self.junit.write()
-
     def print_collected_logs(self) -> None:
         if self.collected_failures:
             if len(self.collected_failures) > 10:
@@ -1185,7 +1198,7 @@ class TestHarness:
         if namebase:
             logfile_base += '-' + namebase.replace(' ', '_')
 
-        self.junit = JunitBuilder(logfile_base + '.junit.xml')
+        self.loggers.append(JunitBuilder(logfile_base + '.junit.xml'))
 
         self.logfilename = logfile_base + '.txt'
         self.jsonlogfilename = logfile_base + '.json'
@@ -1285,6 +1298,9 @@ class TestHarness:
                 mlog.warning('CTRL-C detected, exiting')
                 interrupted = True
 
+        for l in self.loggers:
+            l.start(self)
+
         if sys.platform != 'win32':
             asyncio.get_event_loop().add_signal_handler(signal.SIGINT, sigint_handler)
             asyncio.get_event_loop().add_signal_handler(signal.SIGTERM, sigterm_handler)
@@ -1316,6 +1332,8 @@ class TestHarness:
             if sys.platform != 'win32':
                 asyncio.get_event_loop().remove_signal_handler(signal.SIGINT)
                 asyncio.get_event_loop().remove_signal_handler(signal.SIGTERM)
+            for l in self.loggers:
+                await l.finish(self)
             os.chdir(startdir)
 
 def list_tests(th: TestHarness) -> bool: