googletest/include/gtest/gtest-death-test.h

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// Author: wan@google.com (Zhanyong Wan)
//
// The Google C++ Testing Framework (Google Test)
//
// This header file defines the public API for death tests.  It is
// #included by gtest.h so a user doesn't need to include this
// directly.

#ifndef GTEST_INCLUDE_GTEST_GTEST_DEATH_TEST_H_
#define GTEST_INCLUDE_GTEST_GTEST_DEATH_TEST_H_

#include <gtest/internal/gtest-death-test-internal.h>

namespace testing {

// This flag controls the style of death tests.  Valid values are "threadsafe",
// meaning that the death test child process will re-execute the test binary
// from the start, running only a single death test, or "fast",
// meaning that the child process will execute the test logic immediately
// after forking.
GTEST_DECLARE_string_(death_test_style);

#if GTEST_HAS_DEATH_TEST

// The following macros are useful for writing death tests.

// Here's what happens when an ASSERT_DEATH* or EXPECT_DEATH* is
// executed:
//
//   1. It generates a warning if there is more than one active
//   thread.  This is because it's safe to fork() or clone() only
//   when there is a single thread.
//
//   2. The parent process clone()s a sub-process and runs the death
//   test in it; the sub-process exits with code 0 at the end of the
//   death test, if it hasn't exited already.
//
//   3. The parent process waits for the sub-process to terminate.
//
//   4. The parent process checks the exit code and error message of
//   the sub-process.
//
// Examples:
//
//   ASSERT_DEATH(server.SendMessage(56, "Hello"), "Invalid port number");
//   for (int i = 0; i < 5; i++) {
//     EXPECT_DEATH(server.ProcessRequest(i),
//                  "Invalid request .* in ProcessRequest()")
//         << "Failed to die on request " << i);
//   }
//
//   ASSERT_EXIT(server.ExitNow(), ::testing::ExitedWithCode(0), "Exiting");
//
//   bool KilledBySIGHUP(int exit_code) {
//     return WIFSIGNALED(exit_code) && WTERMSIG(exit_code) == SIGHUP;
//   }
//
//   ASSERT_EXIT(client.HangUpServer(), KilledBySIGHUP, "Hanging up!");
//
// On the regular expressions used in death tests:
//
//   On POSIX-compliant systems (*nix), we use the <regex.h> library,
//   which uses the POSIX extended regex syntax.
//
//   On other platforms (e.g. Windows), we only support a simple regex
//   syntax implemented as part of Google Test.  This limited
//   implementation should be enough most of the time when writing
//   death tests; though it lacks many features you can find in PCRE
//   or POSIX extended regex syntax.  For example, we don't support
//   union ("x|y"), grouping ("(xy)"), brackets ("[xy]"), and
//   repetition count ("x{5,7}"), among others.
//
//   Below is the syntax that we do support.  We chose it to be a
//   subset of both PCRE and POSIX extended regex, so it's easy to
//   learn wherever you come from.  In the following: 'A' denotes a
//   literal character, period (.), or a single \\ escape sequence;
//   'x' and 'y' denote regular expressions; 'm' and 'n' are for
//   natural numbers.
//
//     c     matches any literal character c
//     \\d   matches any decimal digit
//     \\D   matches any character that's not a decimal digit
//     \\f   matches \f
//     \\n   matches \n
//     \\r   matches \r
//     \\s   matches any ASCII whitespace, including \n
//     \\S   matches any character that's not a whitespace
//     \\t   matches \t
//     \\v   matches \v
//     \\w   matches any letter, _, or decimal digit
//     \\W   matches any character that \\w doesn't match
//     \\c   matches any literal character c, which must be a punctuation
//     .     matches any single character except \n
//     A?    matches 0 or 1 occurrences of A
//     A*    matches 0 or many occurrences of A
//     A+    matches 1 or many occurrences of A
//     ^     matches the beginning of a string (not that of each line)
//     $     matches the end of a string (not that of each line)
//     xy    matches x followed by y
//
//   If you accidentally use PCRE or POSIX extended regex features
//   not implemented by us, you will get a run-time failure.  In that
//   case, please try to rewrite your regular expression within the
//   above syntax.
//
//   This implementation is *not* meant to be as highly tuned or robust
//   as a compiled regex library, but should perform well enough for a
//   death test, which already incurs significant overhead by launching
//   a child process.
//
// Known caveats:
//
//   A "threadsafe" style death test obtains the path to the test
//   program from argv[0] and re-executes it in the sub-process.  For
//   simplicity, the current implementation doesn't search the PATH
//   when launching the sub-process.  This means that the user must
//   invoke the test program via a path that contains at least one
//   path separator (e.g. path/to/foo_test and
//   /absolute/path/to/bar_test are fine, but foo_test is not).  This
//   is rarely a problem as people usually don't put the test binary
//   directory in PATH.
//
// TODO(wan@google.com): make thread-safe death tests search the PATH.

// Asserts that a given statement causes the program to exit, with an
// integer exit status that satisfies predicate, and emitting error output
// that matches regex.
#define ASSERT_EXIT(statement, predicate, regex) \
  GTEST_DEATH_TEST_(statement, predicate, regex, GTEST_FATAL_FAILURE_)

// Like ASSERT_EXIT, but continues on to successive tests in the
// test case, if any:
#define EXPECT_EXIT(statement, predicate, regex) \
  GTEST_DEATH_TEST_(statement, predicate, regex, GTEST_NONFATAL_FAILURE_)

// Asserts that a given statement causes the program to exit, either by
// explicitly exiting with a nonzero exit code or being killed by a
// signal, and emitting error output that matches regex.
#define ASSERT_DEATH(statement, regex) \
  ASSERT_EXIT(statement, ::testing::internal::ExitedUnsuccessfully, regex)

// Like ASSERT_DEATH, but continues on to successive tests in the
// test case, if any:
#define EXPECT_DEATH(statement, regex) \
  EXPECT_EXIT(statement, ::testing::internal::ExitedUnsuccessfully, regex)

// Two predicate classes that can be used in {ASSERT,EXPECT}_EXIT*:

// Tests that an exit code describes a normal exit with a given exit code.
class ExitedWithCode {
 public:
  explicit ExitedWithCode(int exit_code);
  bool operator()(int exit_status) const;
 private:
  const int exit_code_;
};

// Tests that an exit code describes an exit due to termination by a
// given signal.
class KilledBySignal {
 public:
  explicit KilledBySignal(int signum);
  bool operator()(int exit_status) const;
 private:
  const int signum_;
};

// EXPECT_DEBUG_DEATH asserts that the given statements die in debug mode.
// The death testing framework causes this to have interesting semantics,
// since the sideeffects of the call are only visible in opt mode, and not
// in debug mode.
//
// In practice, this can be used to test functions that utilize the
// LOG(DFATAL) macro using the following style:
//
// int DieInDebugOr12(int* sideeffect) {
//   if (sideeffect) {
//     *sideeffect = 12;
//   }
//   LOG(DFATAL) << "death";
//   return 12;
// }
//
// TEST(TestCase, TestDieOr12WorksInDgbAndOpt) {
//   int sideeffect = 0;
//   // Only asserts in dbg.
//   EXPECT_DEBUG_DEATH(DieInDebugOr12(&sideeffect), "death");
//
// #ifdef NDEBUG
//   // opt-mode has sideeffect visible.
//   EXPECT_EQ(12, sideeffect);
// #else
//   // dbg-mode no visible sideeffect.
//   EXPECT_EQ(0, sideeffect);
// #endif
// }
//
// This will assert that DieInDebugReturn12InOpt() crashes in debug
// mode, usually due to a DCHECK or LOG(DFATAL), but returns the
// appropriate fallback value (12 in this case) in opt mode. If you
// need to test that a function has appropriate side-effects in opt
// mode, include assertions against the side-effects.  A general
// pattern for this is:
//
// EXPECT_DEBUG_DEATH({
//   // Side-effects here will have an effect after this statement in
//   // opt mode, but none in debug mode.
//   EXPECT_EQ(12, DieInDebugOr12(&sideeffect));
// }, "death");
//
#ifdef NDEBUG

#define EXPECT_DEBUG_DEATH(statement, regex) \
  do { statement; } while (false)

#define ASSERT_DEBUG_DEATH(statement, regex) \
  do { statement; } while (false)

#else

#define EXPECT_DEBUG_DEATH(statement, regex) \
  EXPECT_DEATH(statement, regex)

#define ASSERT_DEBUG_DEATH(statement, regex) \
  ASSERT_DEATH(statement, regex)

#endif  // NDEBUG for EXPECT_DEBUG_DEATH
#endif  // GTEST_HAS_DEATH_TEST
}  // namespace testing

#endif  // GTEST_INCLUDE_GTEST_GTEST_DEATH_TEST_H_