mtest: remove collected_logs

Just reuse the collected_failures collection now that it contains
TestRun objects.  Move the code to generate the short form of the log
to TestRun.

Note that the first line of the error log is not included in
get_log()'s return value, so the magic "first four lines are passed
unscathed" is changed to three lines only.  The resulting output is
like this:

    --- command ---
    <command line>
    --- Listing only the last 100 lines from a long log. ---
    --- stdout ---
    ...

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

mesonbuild/mtest.py

@@ -130,6 +130,13 @@ def add_arguments(parser: argparse.ArgumentParser) -> None:
                         '"subprojname:" to run all tests defined by "subprojname".')
 
 
+def print_safe(s: str) -> None:
+    try:
+        print(s)
+    except UnicodeEncodeError:
+        s = s.encode('ascii', errors='backslashreplace').decode('ascii')
+        print(s)
+
 def returncode_to_status(retcode: int) -> str:
     # Note: We can't use `os.WIFSIGNALED(result.returncode)` and the related
     # functions here because the status returned by subprocess is munged. It
@@ -591,9 +598,21 @@ class TestRun:
             res += self.stde
         if res[-1:] != '\n':
             res += '\n'
-        res += '-------\n\n'
+        res += '-------\n'
         return res
 
+    def get_log_short(self) -> str:
+        log = self.get_log()
+        lines = log.splitlines()
+        if len(lines) < 103:
+            return log
+        else:
+            log = '\n'.join(lines[:2])
+            log += '\n--- Listing only the last 100 lines from a long log. ---\n'
+            log += lines[2] + '\n'
+            log += '\n'.join(lines[-100:])
+            return log
+
 def decode(stream: T.Union[None, bytes]) -> str:
     if stream is None:
         return ''
@@ -879,7 +898,6 @@ class SingleTestRunner:
 class TestHarness:
     def __init__(self, options: argparse.Namespace):
         self.options = options
-        self.collected_logs = []  # type: T.List[str]
         self.collected_failures = []  # type: T.List[TestRun]
         self.fail_count = 0
         self.expectedfail_count = 0
@@ -994,13 +1012,9 @@ class TestHarness:
             self.collected_failures.append(result)
         if not self.options.quiet or not result.res.is_ok():
             print(self.format(result, mlog.colorize_console()))
-        result_str = self.format(result, False)
-        result_str += "\n\n" + result.get_log()
-        if result.res.is_bad():
-            if self.options.print_errorlogs:
-                self.collected_logs.append(result_str)
         if self.logfile:
-            self.logfile.write(result_str)
+            self.logfile.write(self.format(result, False))
+            self.logfile.write("\n\n" + result.get_log() + "\n")
         if self.jsonlogfile:
             write_json_log(self.jsonlogfile, result)
         if self.junit:
@@ -1035,23 +1049,16 @@ class TestHarness:
             self.junit.write()
 
     def print_collected_logs(self) -> None:
-        if self.collected_logs:
-            if len(self.collected_logs) > 10:
-                print('\nThe output from 10 first failed tests:\n')
+        if self.collected_failures:
+            if len(self.collected_failures) > 10:
+                print('\n\nThe output from 10 first failed tests:\n')
             else:
-                print('\nThe output from the failed tests:\n')
-            for log in self.collected_logs[:10]:
-                lines = log.splitlines()
-                if len(lines) > 104:
-                    print('\n'.join(lines[0:4]))
-                    print('--- Listing only the last 100 lines from a long log. ---')
-                    lines = lines[-100:]
-                for line in lines:
-                    try:
-                        print(line)
-                    except UnicodeEncodeError:
-                        line = line.encode('ascii', errors='backslashreplace').decode('ascii')
-                        print(line)
+                print('\n\nThe output from the failed tests:\n')
+            for i, result in enumerate(self.collected_failures, 1):
+                print(self.format(result, mlog.colorize_console()))
+                print_safe(result.get_log_short())
+                if i == 10:
+                    break
 
     def total_failure_count(self) -> int:
         return self.fail_count + self.unexpectedpass_count + self.timeout_count
@@ -1299,7 +1306,8 @@ class TestHarness:
                     break
 
             await complete_all(futures)
-            self.print_collected_logs()
+            if self.options.print_errorlogs:
+                self.print_collected_logs()
             self.print_summary()
 
             if self.logfilename: