handle SIGINT and SIGTERM (#210)

src/halmos/__main__.py

@@ -6,6 +6,7 @@
 import uuid
 import json
 import re
+import signal
 import traceback
 
 from argparse import Namespace
@@ -1325,15 +1326,38 @@ def _main(_args=None) -> MainResult:
 
     timer.create_subtimer("tests")
 
-    #
-    # run
-    #
-
     total_passed = 0
     total_failed = 0
     total_found = 0
     test_results_map = {}
 
+    #
+    # exit and signal handlers to avoid dropping json output
+    #
+
+    def on_exit(exitcode: int) -> MainResult:
+        result = MainResult(exitcode, test_results_map)
+
+        if args.json_output:
+            with open(args.json_output, "w") as json_file:
+                json.dump(asdict(result), json_file, indent=4)
+
+        return result
+
+    def on_signal(signum, frame):
+        if args.debug:
+            debug(f"Signal {signum} received. Dumping {test_results_map}...")
+        exitcode = 128 + signum
+        on_exit(exitcode)
+        sys.exit(exitcode)
+
+    for signum in [signal.SIGINT, signal.SIGTERM]:
+        signal.signal(signum, on_signal)
+
+    #
+    # run
+    #
+
     for build_out_map, filename, contract_name in build_output_iterator(build_out):
         if args.contract and args.contract != contract_name:
             continue
@@ -1404,13 +1428,7 @@ def _main(_args=None) -> MainResult:
         return MainResult(1)
 
     exitcode = 0 if total_failed == 0 else 1
-    result = MainResult(exitcode, test_results_map)
-
-    if args.json_output:
-        with open(args.json_output, "w") as json_file:
-            json.dump(asdict(result), json_file, indent=4)
-
-    return result
+    return on_exit(exitcode)
 
 
 # entrypoint for the `halmos` script

src/halmos/utils.py

@@ -369,6 +369,10 @@ def color_info(text: str) -> str:
     return cyan(text)
 
 
+def color_debug(text: str) -> str:
+    return magenta(text)
+
+
 def error(text: str) -> None:
     print(color_error(text))
 
@@ -381,6 +385,10 @@ def info(text: str) -> None:
     print(color_info(text))
 
 
+def debug(text: str) -> None:
+    print(color_debug(text))
+
+
 def indent_text(text: str, n: int = 4) -> str:
     return "\n".join(" " * n + line for line in text.splitlines())