tests/thread: Improve modthread.c test coverage.

tests/run-tests

@@ -51,7 +51,7 @@ def convert_regex_escapes(line):
 
 
 def run_micropython(pyb, args, test_file):
-    special_tests = ('micropython/meminfo.py', 'basics/bytes_compare3.py')
+    special_tests = ('micropython/meminfo.py', 'basics/bytes_compare3.py', 'thread/thread_exc2.py')
     is_special = False
     if pyb is None:
         # run on PC

tests/thread/thread_exc2.py

+# test raising exception within thread which is not caught
+import utime
+import _thread
+
+def thread_entry():
+    raise ValueError
+
+_thread.start_new_thread(thread_entry, ())
+utime.sleep(1)
+print('done')

tests/thread/thread_exc2.py.exp

+Unhandled exception in thread started by <function thread_entry at 0x\[0-9a-f\]\+>
+Traceback (most recent call last):
+  File "thread/thread_exc2.py", line 6, in thread_entry
+ValueError: 
+done

tests/thread/thread_start2.py

@@ -16,4 +16,11 @@ _thread.start_new_thread(thread_entry, (10, 20), {'a2': 0, 'a3': 1})
 
 # wait for thread to finish
 time.sleep(1)
+
+# incorrect argument where dictionary is needed for keyword args
+try:
+    _thread.start_new_thread(thread_entry, (), ())
+except TypeError:
+    print('TypeError')
+
 print('done')