theia/test: make pexpect easier to debug

by logging the process output

software/theia/test/test.py

@@ -89,6 +89,15 @@ class TestTheia(SlapOSInstanceTestCase):
     # use a large enough terminal so that slapos proxy show table fit in the screen
     process.setwinsize(5000, 5000)
 
+    # log process output for debugging
+    logger = logging.getLogger('theia-shell')
+    class DebugLogFile:
+      def write(self, msg):
+        logger.info("output from theia-shell: %s", msg)
+      def flush(self):
+        pass
+    process.logfile = DebugLogFile()
+
     process.expect_exact('Standalone SlapOS: Formatting 20 partitions')
     process.expect_exact('Standalone SlapOS for computer `local` activated')