matplotlib
diff --git a/‎lib/matplotlib/backends/backend_macosx.py
Lines changed: 33 additions & 1 deletion b/‎lib/matplotlib/backends/backend_macosx.py
Lines changed: 33 additions & 1 deletion
diff --git a/‎lib/matplotlib/backends/qt_compat.py
Lines changed: 37 additions & 39 deletions b/‎lib/matplotlib/backends/qt_compat.py
Lines changed: 37 additions & 39 deletions
diff --git a/‎lib/matplotlib/testing/__init__.py
Lines changed: 27 additions & 0 deletions b/‎lib/matplotlib/testing/__init__.py
Lines changed: 27 additions & 0 deletions
@@ -1,4 +1,6 @@
 import os
+import signal
+import socket
 
 import matplotlib as mpl
 from matplotlib import _api, cbook
@@ -164,7 +166,37 @@ def destroy(self):
 
     @classmethod
     def start_main_loop(cls):
-        _macosx.show()
+        # Set up a SIGINT handler to allow terminating a plot via CTRL-C.
+        # The logic is largely copied from qt_compat._maybe_allow_interrupt; see its
+        # docstring for details.  Parts are implemented by wake_on_fd_write in ObjC.
+
+        old_sigint_handler = signal.getsignal(signal.SIGINT)
+        if old_sigint_handler in (None, signal.SIG_IGN, signal.SIG_DFL):
+            _macosx.show()
+            return
+
+        handler_args = None
+        wsock, rsock = socket.socketpair()
+        wsock.setblocking(False)
+        rsock.setblocking(False)
+        old_wakeup_fd = signal.set_wakeup_fd(wsock.fileno())
+        _macosx.wake_on_fd_write(rsock.fileno())
+
+        def handle(*args):
+            nonlocal handler_args
+            handler_args = args
+            _macosx.stop()
+
+        signal.signal(signal.SIGINT, handle)
+        try:
+            _macosx.show()
+        finally:
+            wsock.close()
+            rsock.close()
+            signal.set_wakeup_fd(old_wakeup_fd)
+            signal.signal(signal.SIGINT, old_sigint_handler)
+            if handler_args is not None:
+                old_sigint_handler(*handler_args)
 
     def show(self):
         if not self._shown:
 
@@ -198,48 +198,46 @@ def _maybe_allow_interrupt(qapp):
     that a non-python handler was installed, i.e. in Julia, and not SIG_IGN
     which means we should ignore the interrupts.
     """
+
     old_sigint_handler = signal.getsignal(signal.SIGINT)
-    handler_args = None
-    skip = False
     if old_sigint_handler in (None, signal.SIG_IGN, signal.SIG_DFL):
-        skip = True
-    else:
-        wsock, rsock = socket.socketpair()
-        wsock.setblocking(False)
-        old_wakeup_fd = signal.set_wakeup_fd(wsock.fileno())
-        sn = QtCore.QSocketNotifier(
-            rsock.fileno(), _enum('QtCore.QSocketNotifier.Type').Read
-        )
+        yield
+        return
+
+    handler_args = None
+    wsock, rsock = socket.socketpair()
+    wsock.setblocking(False)
+    rsock.setblocking(False)
+    old_wakeup_fd = signal.set_wakeup_fd(wsock.fileno())
+    sn = QtCore.QSocketNotifier(
+        rsock.fileno(), _enum('QtCore.QSocketNotifier.Type').Read)
+
+    # We do not actually care about this value other than running some Python code to
+    # ensure that the interpreter has a chance to handle the signal in Python land.  We
+    # also need to drain the socket because it will be written to as part of the wakeup!
+    # There are some cases where this may fire too soon / more than once on Windows so
+    # we should be forgiving about reading an empty socket.
+    # Clear the socket to re-arm the notifier.
+    @sn.activated.connect
+    def _may_clear_sock(*args):
+        try:
+            rsock.recv(1)
+        except BlockingIOError:
+            pass
+
+    def handle(*args):
+        nonlocal handler_args
+        handler_args = args
+        qapp.quit()
 
-        # We do not actually care about this value other than running some
-        # Python code to ensure that the interpreter has a chance to handle the
-        # signal in Python land.  We also need to drain the socket because it
-        # will be written to as part of the wakeup!  There are some cases where
-        # this may fire too soon / more than once on Windows so we should be
-        # forgiving about reading an empty socket.
-        rsock.setblocking(False)
-        # Clear the socket to re-arm the notifier.
-        @sn.activated.connect
-        def _may_clear_sock(*args):
-            try:
-                rsock.recv(1)
-            except BlockingIOError:
-                pass
-
-        def handle(*args):
-            nonlocal handler_args
-            handler_args = args
-            qapp.quit()
-
-        signal.signal(signal.SIGINT, handle)
+    signal.signal(signal.SIGINT, handle)
     try:
         yield
     finally:
-        if not skip:
-            wsock.close()
-            rsock.close()
-            sn.setEnabled(False)
-            signal.set_wakeup_fd(old_wakeup_fd)
-            signal.signal(signal.SIGINT, old_sigint_handler)
-            if handler_args is not None:
-                old_sigint_handler(*handler_args)
+        wsock.close()
+        rsock.close()
+        sn.setEnabled(False)
+        signal.set_wakeup_fd(old_wakeup_fd)
+        signal.signal(signal.SIGINT, old_sigint_handler)
+        if handler_args is not None:
+            old_sigint_handler(*handler_args)
@@ -173,6 +173,33 @@ def _check_for_pgf(texsystem):
         return True
 
 
+class _WaitForStringPopen(subprocess.Popen):
+    """
+    A Popen that passes flags that allow triggering KeyboardInterrupt.
+    """
+
+    def __init__(self, *args, **kwargs):
+        if sys.platform == 'win32':
+            kwargs['creationflags'] = subprocess.CREATE_NEW_CONSOLE
+        super().__init__(
+            *args, **kwargs,
+            # Force Agg so that each test can switch to its desired Qt backend.
+            env={**os.environ, "MPLBACKEND": "Agg", "SOURCE_DATE_EPOCH": "0"},
+            stdout=subprocess.PIPE, universal_newlines=True)
+
+    def wait_for(self, terminator):
+        """Read until the terminator is reached."""
+        buf = ''
+        while True:
+            c = self.stdout.read(1)
+            if not c:
+                raise RuntimeError(
+                    f'Subprocess died before emitting expected {terminator!r}')
+            buf += c
+            if buf.endswith(terminator):
+                return
+
+
 def _has_tex_package(package):
     try:
         mpl.dviread.find_tex_file(f"{package}.sty")