Add a proper unit test for xreload.py.

Lib/test/test_xreload.py

+"""Doctests for module reloading.
+
+>>> from xreload import xreload
+>>> from test.test_xreload import make_mod
+>>> make_mod()
+>>> import x
+>>> C = x.C
+>>> Cfoo = C.foo
+>>> Cbar = C.bar
+>>> Cstomp = C.stomp
+>>> b = C()
+>>> bfoo = b.foo
+>>> b.foo()
+42
+>>> bfoo()
+42
+>>> Cfoo(b)
+42
+>>> Cbar()
+42 42
+>>> Cstomp()
+42 42 42
+>>> make_mod(repl="42", subst="24")
+>>> xreload(x)
+<module 'x' (built-in)>
+>>> b.foo()
+24
+>>> bfoo()
+24
+>>> Cfoo(b)
+24
+>>> Cbar()
+24 24
+>>> Cstomp()
+24 24 24
+
+"""
+
+SAMPLE_CODE = """
+class C:
+    def foo(self):
+        print(42)
+    @classmethod
+    def bar(cls):
+        print(42, 42)
+    @staticmethod
+    def stomp():
+        print (42, 42, 42)
+"""
+
+import os
+import sys
+import shutil
+import doctest
+import xreload
+import tempfile
+from test.test_support import run_unittest
+
+tempdir = None
+save_path = None
+
+
+def setUp(unused=None):
+    global tempdir, save_path
+    tempdir = tempfile.mkdtemp()
+    save_path = list(sys.path)
+    sys.path.append(tempdir)
+
+
+def tearDown(unused=None):
+    global tempdir, save_path
+    if save_path is not None:
+        sys.path = save_path
+        save_path = None
+    if tempdir is not None:
+        shutil.rmtree(tempdir)
+        tempdir = None
+        
+
+def make_mod(name="x", repl=None, subst=None):
+    if not tempdir:
+        setUp()
+        assert tempdir
+    fn = os.path.join(tempdir, name + ".py")
+    f = open(fn, "w")
+    sample = SAMPLE_CODE
+    if repl is not None and subst is not None:
+        sample = sample.replace(repl, subst)
+    try:
+        f.write(sample)
+    finally:
+        f.close()
+
+
+def test_suite():
+    return doctest.DocTestSuite(setUp=setUp, tearDown=tearDown)
+
+
+def test_main():
+    run_unittest(test_suite())
+
+if __name__ == "__main__":
+    test_main()