run-tests: add support for marking tests as very slow

I want to add tests for our packaging rules, but those necessarily run
a whole build, or possibly two if both native packaging and docker are
available. This lets us flag such tests with a `#require slow` so that
they don't unnecessarily slow down normal test runs.

tests/hghave.py

@@ -427,3 +427,7 b' def has_py3k():'
 @check("pure", "running with pure Python code")
 def has_pure():
     return os.environ.get("HGTEST_RUN_TESTS_PURE") == "--pure"
+
+@check("slow", "allow slow tests")
+def has_slow():
+    return os.environ.get('HGTEST_SLOW') == 'slow'

tests/run-tests.py

@@ -259,6 +259,8 b' def getparser():'
                       help='run tests in random order')
     parser.add_option('--profile-runner', action='store_true',
                       help='run statprof on run-tests')
+    parser.add_option('--allow-slow-tests', action='store_true',
+                      help='allow extremely slow tests')
 
     for option, (envvar, default) in defaults.items():
         defaults[option] = type(default)(os.environ.get(envvar, default))
@@ -1835,6 +1837,11 b' class TestRunner(object):'
         if self.options.pure:
             os.environ["HGTEST_RUN_TESTS_PURE"] = "--pure"
 
+        if self.options.allow_slow_tests:
+            os.environ["HGTEST_SLOW"] = "slow"
+        elif 'HGTEST_SLOW' in os.environ:
+            del os.environ['HGTEST_SLOW']
+
         self._coveragefile = os.path.join(self._testdir, b'.coverage')
 
         vlog("# Using TESTDIR", self._testdir)

tests/test-run-tests.t

@@ -621,3 +621,17 b' test that TESTDIR is referred in PATH'
   # Ran 1 tests, 0 skipped, 0 warned, 0 failed.
 
 #endif
+
+test support for --allow-slow-tests
+  $ cat > test-very-slow-test.t <<EOF
+  > #require slow
+  >   $ echo pass
+  >   pass
+  > EOF
+  $ run-tests.py test-very-slow-test.t
+  s
+  Skipped test-very-slow-test.t: skipped
+  # Ran 0 tests, 1 skipped, 0 warned, 0 failed.
+  $ run-tests.py --allow-slow-tests test-very-slow-test.t
+  .
+  # Ran 1 tests, 0 skipped, 0 warned, 0 failed.