Tests: Add test for abort

Author: https://github.com/mhermier
Commit: https://github.com/SerenityOS/serenity/commit/181f759dc93
Pull-request: https://github.com/SerenityOS/serenity/pull/11291

Tests/LibC/CMakeLists.txt

@@ -1,4 +1,5 @@
 set(TEST_SOURCES
+    TestAbort.cpp
     TestIo.cpp
     TestLibCExec.cpp
     TestLibCDirEnt.cpp

Tests/LibC/TestAbort.cpp

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2021, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <assert.h> // FIXME: Remove when `_abort` is moved to <stdlib.h>
+#include <stdlib.h>
+
+TEST_CASE(_abort)
+{
+    EXPECT_CRASH("This should _abort", [] {
+        _abort();
+        return Test::Crash::Failure::DidNotCrash;
+    });
+}
+
+TEST_CASE(abort)
+{
+    EXPECT_CRASH("This should abort", [] {
+        abort();
+        return Test::Crash::Failure::DidNotCrash;
+    });
+}