kernel32/tests: Add test to show that multiple user APCs are processed at once.

dlls/kernel32/tests/sync.c

@@ -2333,6 +2333,13 @@ static DWORD WINAPI alertable_wait_thread(void *param)
     todo_wine
     ok(status == STATUS_WAIT_0, "expected STATUS_WAIT_0, got %08x\n", status);
 
+    ReleaseSemaphore(semaphores[0], 1, NULL);
+    timeout.QuadPart = -10000000;
+    status = pNtWaitForMultipleObjects(1, &semaphores[1], FALSE, TRUE, &timeout);
+    ok(status == STATUS_USER_APC, "expected STATUS_USER_APC, got %08x\n", status);
+    result = WaitForSingleObject(semaphores[0], 0);
+    ok(result == WAIT_TIMEOUT, "expected WAIT_TIMEOUT, got %u\n", result);
+
     return 0;
 }
 
@@ -2342,12 +2349,21 @@ static void CALLBACK alertable_wait_apc(ULONG_PTR userdata)
     ReleaseSemaphore(semaphores[1], 1, NULL);
 }
 
+static void CALLBACK alertable_wait_apc2(ULONG_PTR userdata)
+{
+    HANDLE *semaphores = (void *)userdata;
+    DWORD result;
+
+    result = WaitForSingleObject(semaphores[0], 1000);
+    ok(result == WAIT_OBJECT_0, "expected WAIT_OBJECT_0, got %u\n", result);
+}
+
 static void test_alertable_wait(void)
 {
     HANDLE thread, semaphores[2];
     DWORD result;
 
-    semaphores[0] = CreateSemaphoreW(NULL, 0, 1, NULL);
+    semaphores[0] = CreateSemaphoreW(NULL, 0, 2, NULL);
     ok(semaphores[0] != NULL, "CreateSemaphore failed with %u\n", GetLastError());
     semaphores[1] = CreateSemaphoreW(NULL, 0, 1, NULL);
     ok(semaphores[1] != NULL, "CreateSemaphore failed with %u\n", GetLastError());
@@ -2366,6 +2382,15 @@ static void test_alertable_wait(void)
     result = QueueUserAPC(alertable_wait_apc, thread, (ULONG_PTR)semaphores);
     ok(result != 0, "QueueUserAPC failed with %u\n", GetLastError());
 
+    result = WaitForSingleObject(semaphores[0], 1000);
+    ok(result == WAIT_OBJECT_0, "expected WAIT_OBJECT_0, got %u\n", result);
+    Sleep(100); /* ensure the thread is blocking in NtWaitForMultipleObjects */
+    result = QueueUserAPC(alertable_wait_apc2, thread, (ULONG_PTR)semaphores);
+    ok(result != 0, "QueueUserAPC failed with %u\n", GetLastError());
+    result = QueueUserAPC(alertable_wait_apc2, thread, (ULONG_PTR)semaphores);
+    ok(result != 0, "QueueUserAPC failed with %u\n", GetLastError());
+    ReleaseSemaphore(semaphores[0], 2, NULL);
+
     result = WaitForSingleObject(thread, 1000);
     ok(result == WAIT_OBJECT_0, "expected WAIT_OBJECT_0, got %u\n", result);
     CloseHandle(thread);