run-tests: pass temp dir into Test.__init__

This patch starts a mini series of moving arguments to Test.__init__
from semi-complex data structures (such as the command options) to named
arguments. This will allow Test instances to be more easily instantiated
from other contexts. This improves the ability to run Mercurial tests in
new and different environments.

tests/run-tests.py

@@ -338,7 +338,7 b' class Test(unittest.TestCase):'
     # Status code reserved for skipped tests (used by hghave).
     SKIPPED_STATUS = 80
 
-    def __init__(self, runner, path, count):
+    def __init__(self, runner, path, count, tmpdir):
         """Create a test from parameters.
 
         runner is a TestRunner instance.
@@ -346,6 +346,8 b' class Test(unittest.TestCase):'
         path is the full path to the file defining the test.
 
         count is an identifier used to denote this test instance.
+
+        tmpdir is the main temporary directory to use for this test.
         """
 
         self._path = path
@@ -356,6 +358,7 b' class Test(unittest.TestCase):'
         self._runner = runner
         self._options = runner.options
         self._count = count
+        self._threadtmp = tmpdir
         self._daemonpids = []
 
         self._finished = None
@@ -375,8 +378,6 b' class Test(unittest.TestCase):'
         else:
             self._refout = []
 
-        self._threadtmp = os.path.join(runner.hgtmp, 'child%d' % count)
-
     def __str__(self):
         return self.name
 
@@ -1467,7 +1468,10 b' class TestRunner(object):'
                 testcls = cls
                 break
 
-        return testcls(self, os.path.join(self.testdir, test), count)
+        refpath = os.path.join(self.testdir, test)
+        tmpdir = os.path.join(self.hgtmp, 'child%d' % count)
+
+        return testcls(self, refpath, count, tmpdir)
 
     def _cleanup(self):
         """Clean up state from this test invocation."""