unittest: Add dummy implementation (just a TestCase class with few methods).

unittest/unittest.py

@@ -0,0 +1,25 @@
+class TestCase:
+
+    def fail(self, msg):
+        assert False, msg
+
+    def assertEqual(self, x, y):
+        assert x == y, "%r vs %r" % (x, y)
+
+    def assertTrue(self, x):
+        assert x
+
+    def assertIn(self, x, y):
+        assert x in y
+
+    def assertIsInstance(self, x, y):
+        assert isinstance(x, y)
+
+    def assertRaises(self, exc, func, *args):
+        try:
+            func(*args)
+            assert False, "%r not raised" % exc
+        except Exception as e:
+            if isinstance(e, exc):
+                return
+            raise