LibTest: Expose new EXPECT_CRASH(..) macro for unit test assertions

Utilize the Crash type we imported into LibTest to support testing
of crash scenarios when testing all other components.

Userland/Libraries/LibTest/CrashTest.cpp

@@ -13,16 +13,16 @@
 namespace Test {
 
 Crash::Crash(String test_type, Function<Crash::Failure()> crash_function)
-    : m_type(test_type)
+    : m_type(move(test_type))
     , m_crash_function(move(crash_function))
 {
 }
 
-void Crash::run(RunType run_type = RunType::UsingChildProcess)
+bool Crash::run(RunType run_type)
 {
     printf("\x1B[33mTesting\x1B[0m: \"%s\"\n", m_type.characters());
 
-    auto run_crash_and_print_if_error = [this]() {
+    auto run_crash_and_print_if_error = [this]() -> bool {
         auto failure = m_crash_function();
 
         // If we got here something went wrong
@@ -37,10 +37,11 @@ void Crash::run(RunType run_type = RunType::UsingChildProcess)
         default:
             VERIFY_NOT_REACHED();
         }
+        return false;
     };
 
     if (run_type == RunType::UsingCurrentProcess) {
-        run_crash_and_print_if_error();
+        return run_crash_and_print_if_error();
     } else {
 
         // Run the test in a child process so that we do not crash the crash program :^)
@@ -55,8 +56,11 @@ void Crash::run(RunType run_type = RunType::UsingChildProcess)
 
         int status;
         waitpid(pid, &status, 0);
-        if (WIFSIGNALED(status))
+        if (WIFSIGNALED(status)) {
             printf("\x1B[32mPASS\x1B[0m: Terminated with signal %d\n", WTERMSIG(status));
+            return true;
+        }
+        return false;
     }
 }
 

Userland/Libraries/LibTest/CrashTest.h

@@ -27,7 +27,7 @@ public:
 
     Crash(String test_type, Function<Crash::Failure()> crash_function);
 
-    void run(RunType run_type);
+    bool run(RunType run_type = RunType::UsingChildProcess);
 
 private:
     String m_type;

Userland/Libraries/LibTest/Macros.h

@@ -9,6 +9,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/CheckedFormatString.h>
+#include <LibTest/CrashTest.h>
 
 namespace AK {
 template<typename... Parameters>
@@ -101,3 +102,14 @@ void current_test_case_did_fail();
         ::AK::warnln("\033[31;1mFAIL\033[0m: {}:{}: {}", __FILE__, __LINE__, message); \
         ::Test::current_test_case_did_fail();                                          \
     } while (false)
+
+// To use, specify the lambda to execute in a sub process and verify it exits:
+//  EXPECT_CRASH("This should fail", []{
+//      return Test::Crash::Failure::DidNotCrash;
+//  });
+#define EXPECT_CRASH(test_message, test_func)       \
+    do {                                            \
+        Test::Crash crash(test_message, test_func); \
+        if (!crash.run())                           \
+            ::Test::current_test_case_did_fail();   \
+    } while (false)