test: a test for --save-signal

Author: nedbat

coverage/cmdline.py

@@ -822,7 +822,7 @@ def do_help(
 
     def do_signal_save(self, _signum: int, _frame: types.FrameType | None) -> None:
         """ Signal handler to save coverage report """
-        print("Saving coverage data ...")
+        print("Saving coverage data ...", flush=True)
         self.coverage.save()
 
     def do_run(self, options: optparse.Values, args: list[str]) -> int:

tests/helpers.py

@@ -13,6 +13,7 @@
 import os
 import os.path
 import re
+import shlex
 import shutil
 import subprocess
 import sys
@@ -47,7 +48,7 @@ def _correct_encoding() -> str:
     return encoding
 
 
-def subprocess_popen(cmd: str) -> subprocess.Popen[bytes]:
+def subprocess_popen(cmd: str, shell: bool=True) -> subprocess.Popen[bytes]:
     """Run a command in a subprocess.
 
     Returns the Popen object.
@@ -66,9 +67,12 @@ def subprocess_popen(cmd: str) -> subprocess.Popen[bytes]:
     sub_env = dict(os.environ)
     sub_env["PYTHONIOENCODING"] = _correct_encoding()
 
+    if not shell:
+        cmd = shlex.split(cmd)  # type: ignore[assignment]
+
     proc = subprocess.Popen(
         cmd,
-        shell=True,
+        shell=shell,
         env=sub_env,
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,

tests/test_process.py

@@ -11,9 +11,11 @@
 import os.path
 import platform
 import re
+import signal
 import stat
 import sys
 import textwrap
+import time
 
 from pathlib import Path
 from typing import Any
@@ -27,7 +29,7 @@
 
 from tests import testenv
 from tests.coveragetest import CoverageTest, TESTS_DIR
-from tests.helpers import re_line, re_lines, re_lines_text
+from tests.helpers import re_line, re_lines, re_lines_text, subprocess_popen
 
 
 class ProcessTest(CoverageTest):
@@ -458,6 +460,33 @@ def test_os_exit(self, patch: bool) -> None:
         else:
             assert seen < total_lines
 
+    @pytest.mark.skipif(env.WINDOWS, reason="Windows can't do --save-signal")
+    @pytest.mark.parametrize("send", [False, True])
+    def test_save_signal(self, send: bool) -> None:
+        # PyPy on Ubuntu seems to need more time for things to happen.
+        base_time = 0.75 if (env.PYPY and env.LINUX) else 0.0
+        self.make_file("loop.py", """\
+            import time
+            print("Starting", flush=True)
+            while True:
+                time.sleep(.02)
+            """)
+        proc = subprocess_popen("coverage run --save-signal=USR1 loop.py", shell=False)
+        time.sleep(base_time + .25)
+        if send:
+            proc.send_signal(signal.SIGUSR1)
+            time.sleep(base_time + .25)
+        proc.kill()
+        proc.wait(timeout=base_time + .25)
+        stdout, _ = proc.communicate()
+        assert b"Starting" in stdout
+        if send:
+            self.assert_exists(".coverage")
+            assert b"Saving coverage data" in stdout
+        else:
+            self.assert_doesnt_exist(".coverage")
+            assert b"Saving coverage data" not in stdout
+
     def test_warnings_during_reporting(self) -> None:
         # While fixing issue #224, the warnings were being printed far too
         # often.  Make sure they're not any more.