Add a complete ast expression test

And fix missing bits in the ast expression evaluator:

* boolean conversion
* & and | bit operators

lib/rcUtilities.py

@@ -23,6 +23,8 @@
     ast.Mult: op.mul,
     ast.Div: op.truediv,
     ast.Pow: op.pow,
+    ast.BitOr: op.or_,
+    ast.BitAnd: op.and_,
     ast.BitXor: op.xor,
     ast.USub: op.neg,
     ast.FloorDiv: op.floordiv,
@@ -41,11 +43,14 @@ def eval_expr(expr):
     """ arithmetic expressions evaluator
     """
     def eval_(node):
+        _safe_names = {'None': None, 'True': True, 'False': False}
         if isinstance(node, ast.Num): # <number>
             return node.n
         elif isinstance(node, ast.Str):
             return node.s
         elif isinstance(node, ast.Name):
+            if node.id in _safe_names:
+                return _safe_names[node.id]
             return node.id
         elif isinstance(node, ast.Tuple):
             return tuple(node.elts)

lib/tests/test_expr.py

@@ -0,0 +1,32 @@
+from __future__ import print_function
+from rcUtilities import eval_expr
+
+def test_expr():
+    expressions = (
+        ("1+2", 3),
+        ("a+b", "ab"),
+        ("a+'b'", "ab"),
+        ("a in (a, b, 1)", True),
+        ("a in (b, 1)", False),
+        ("a == b", False),
+        ("a == a", True),
+        ("0 == 0", True),
+        ("0 == 1", False),
+        ("0 > 1", False),
+        ("0 < 1", True),
+        ("0 >= 0", True),
+        ("1 >= 0", True),
+        ("1 <= 0", False),
+        ("0 <= 0", True),
+        ("False and False", False),
+        ("True and False", False),
+        ("True and True", True),
+        ("True or False", True),
+        ("True or True", True),
+        ("False or False", False),
+        ("0 & 1", False),
+    )
+    for expr, expected in expressions:
+        result = eval_expr(expr)
+        print(expr, "=>", result, "expect:", expected)
+        assert result == expected