mtest: add support for hard errors

Hard errors also come from the GNU Automake test protocol.  They happen when
e.g., the set-up of a test case scenario fails, or when some
other unexpected or highly undesirable condition is encountered.

TAP will use them for parse errors too.  Add them to the exitcode protocol
first.

docs/markdown/Unit-tests.md

@@ -51,10 +51,12 @@ By default Meson uses as many concurrent processes as there are cores on the tes
 $ MESON_TESTTHREADS=5 ninja test
 ```
 
-## Skipped tests
+## Skipped tests and hard errors
 
 Sometimes a test can only determine at runtime that it can not be run. The GNU standard approach in this case is to exit the program with error code 77. Meson will detect this and report these tests as skipped rather than failed. This behavior was added in version 0.37.0.
 
+In addition, sometimes a test fails set up so that it should fail even if it is marked as an expected failure. The GNU standard approach in this case is to exit the program with error code 99. Again, Meson will detect this and report these tests as `ERROR`, ignoring the setting of `should_fail`. This behavior was added in version 0.50.0.
+
 ## Testing tool
 
 The goal of the meson test tool is to provide a simple way to run tests in a variety of different ways. The tool is designed to be run in the build directory.

mesonbuild/mtest.py

@@ -36,6 +36,10 @@
 # mean that the test should be skipped.
 GNU_SKIP_RETURNCODE = 77
 
+# GNU autotools interprets a return code of 99 from tests it executes to
+# mean that the test failed even before testing what it is supposed to test.
+GNU_ERROR_RETURNCODE = 99
+
 def is_windows():
     platname = platform.system().lower()
     return platname == 'windows' or 'mingw' in platname
@@ -146,18 +150,21 @@ class TestResult(enum.Enum):
     FAIL = 'FAIL'
     EXPECTEDFAIL = 'EXPECTEDFAIL'
     UNEXPECTEDPASS = 'UNEXPECTEDPASS'
+    ERROR = 'ERROR'
 
 
 class TestRun:
     @staticmethod
     def make_exitcode(test, returncode, duration, stdo, stde, cmd):
         if returncode == GNU_SKIP_RETURNCODE:
             res = TestResult.SKIP
+        elif returncode == GNU_ERROR_RETURNCODE:
+            res = TestResult.ERROR
         elif test.should_fail:
             res = TestResult.EXPECTEDFAIL if bool(returncode) else TestResult.UNEXPECTEDPASS
         else:
             res = TestResult.FAIL if bool(returncode) else TestResult.OK
-        return TestRun(test, res, returncode, test.should_fail, duration, stdo, stde, cmd, test.env)
+        return TestRun(test, res, returncode, duration, stdo, stde, cmd)
 
     def __init__(self, test, res, returncode, duration, stdo, stde, cmd):
         assert isinstance(res, TestResult)
@@ -474,7 +481,7 @@ def process_test_result(self, result):
             self.skip_count += 1
         elif result.res is TestResult.OK:
             self.success_count += 1
-        elif result.res is TestResult.FAIL:
+        elif result.res is TestResult.FAIL or result.res is TestResult.ERROR:
             self.fail_count += 1
         elif result.res is TestResult.EXPECTEDFAIL:
             self.expectedfail_count += 1
@@ -496,7 +503,8 @@ def print_stats(self, numlen, tests, name, result, i):
             (num, name, padding1, result.res.value, padding2, result.duration,
              status)
         ok_statuses = (TestResult.OK, TestResult.EXPECTEDFAIL)
-        bad_statuses = (TestResult.FAIL, TestResult.TIMEOUT, TestResult.UNEXPECTEDPASS)
+        bad_statuses = (TestResult.FAIL, TestResult.TIMEOUT, TestResult.UNEXPECTEDPASS,
+                        TestResult.ERROR)
         if not self.options.quiet or result.res not in ok_statuses:
             if result.res not in ok_statuses and mlog.colorize_console:
                 if result.res in bad_statuses:

test cases/failing test/4 hard error/main.c

@@ -0,0 +1,3 @@
+int main(void) {
+    return 99;
+}

test cases/failing test/4 hard error/meson.build

@@ -0,0 +1,4 @@
+project('trivial', 'c')
+
+# Exit code 99 even overrides should_fail
+test('My Test', executable('main', 'main.c'), should_fail: true)