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Diffstat (limited to 'python/pytest/_pytest/assertion/reinterpret.py')
| -rw-r--r-- | python/pytest/_pytest/assertion/reinterpret.py | 407 |
1 files changed, 407 insertions, 0 deletions
diff --git a/python/pytest/_pytest/assertion/reinterpret.py b/python/pytest/_pytest/assertion/reinterpret.py new file mode 100644 index 000000000..f4262c3ac --- /dev/null +++ b/python/pytest/_pytest/assertion/reinterpret.py @@ -0,0 +1,407 @@ +""" +Find intermediate evalutation results in assert statements through builtin AST. +""" +import ast +import sys + +import _pytest._code +import py +from _pytest.assertion import util +u = py.builtin._totext + + +class AssertionError(util.BuiltinAssertionError): + def __init__(self, *args): + util.BuiltinAssertionError.__init__(self, *args) + if args: + # on Python2.6 we get len(args)==2 for: assert 0, (x,y) + # on Python2.7 and above we always get len(args) == 1 + # with args[0] being the (x,y) tuple. + if len(args) > 1: + toprint = args + else: + toprint = args[0] + try: + self.msg = u(toprint) + except Exception: + self.msg = u( + "<[broken __repr__] %s at %0xd>" + % (toprint.__class__, id(toprint))) + else: + f = _pytest._code.Frame(sys._getframe(1)) + try: + source = f.code.fullsource + if source is not None: + try: + source = source.getstatement(f.lineno, assertion=True) + except IndexError: + source = None + else: + source = str(source.deindent()).strip() + except py.error.ENOENT: + source = None + # this can also occur during reinterpretation, when the + # co_filename is set to "<run>". + if source: + self.msg = reinterpret(source, f, should_fail=True) + else: + self.msg = "<could not determine information>" + if not self.args: + self.args = (self.msg,) + +if sys.version_info > (3, 0): + AssertionError.__module__ = "builtins" + +if sys.platform.startswith("java"): + # See http://bugs.jython.org/issue1497 + _exprs = ("BoolOp", "BinOp", "UnaryOp", "Lambda", "IfExp", "Dict", + "ListComp", "GeneratorExp", "Yield", "Compare", "Call", + "Repr", "Num", "Str", "Attribute", "Subscript", "Name", + "List", "Tuple") + _stmts = ("FunctionDef", "ClassDef", "Return", "Delete", "Assign", + "AugAssign", "Print", "For", "While", "If", "With", "Raise", + "TryExcept", "TryFinally", "Assert", "Import", "ImportFrom", + "Exec", "Global", "Expr", "Pass", "Break", "Continue") + _expr_nodes = set(getattr(ast, name) for name in _exprs) + _stmt_nodes = set(getattr(ast, name) for name in _stmts) + def _is_ast_expr(node): + return node.__class__ in _expr_nodes + def _is_ast_stmt(node): + return node.__class__ in _stmt_nodes +else: + def _is_ast_expr(node): + return isinstance(node, ast.expr) + def _is_ast_stmt(node): + return isinstance(node, ast.stmt) + +try: + _Starred = ast.Starred +except AttributeError: + # Python 2. Define a dummy class so isinstance() will always be False. + class _Starred(object): pass + + +class Failure(Exception): + """Error found while interpreting AST.""" + + def __init__(self, explanation=""): + self.cause = sys.exc_info() + self.explanation = explanation + + +def reinterpret(source, frame, should_fail=False): + mod = ast.parse(source) + visitor = DebugInterpreter(frame) + try: + visitor.visit(mod) + except Failure: + failure = sys.exc_info()[1] + return getfailure(failure) + if should_fail: + return ("(assertion failed, but when it was re-run for " + "printing intermediate values, it did not fail. Suggestions: " + "compute assert expression before the assert or use --assert=plain)") + +def run(offending_line, frame=None): + if frame is None: + frame = _pytest._code.Frame(sys._getframe(1)) + return reinterpret(offending_line, frame) + +def getfailure(e): + explanation = util.format_explanation(e.explanation) + value = e.cause[1] + if str(value): + lines = explanation.split('\n') + lines[0] += " << %s" % (value,) + explanation = '\n'.join(lines) + text = "%s: %s" % (e.cause[0].__name__, explanation) + if text.startswith('AssertionError: assert '): + text = text[16:] + return text + +operator_map = { + ast.BitOr : "|", + ast.BitXor : "^", + ast.BitAnd : "&", + ast.LShift : "<<", + ast.RShift : ">>", + ast.Add : "+", + ast.Sub : "-", + ast.Mult : "*", + ast.Div : "/", + ast.FloorDiv : "//", + ast.Mod : "%", + ast.Eq : "==", + ast.NotEq : "!=", + ast.Lt : "<", + ast.LtE : "<=", + ast.Gt : ">", + ast.GtE : ">=", + ast.Pow : "**", + ast.Is : "is", + ast.IsNot : "is not", + ast.In : "in", + ast.NotIn : "not in" +} + +unary_map = { + ast.Not : "not %s", + ast.Invert : "~%s", + ast.USub : "-%s", + ast.UAdd : "+%s" +} + + +class DebugInterpreter(ast.NodeVisitor): + """Interpret AST nodes to gleam useful debugging information. """ + + def __init__(self, frame): + self.frame = frame + + def generic_visit(self, node): + # Fallback when we don't have a special implementation. + if _is_ast_expr(node): + mod = ast.Expression(node) + co = self._compile(mod) + try: + result = self.frame.eval(co) + except Exception: + raise Failure() + explanation = self.frame.repr(result) + return explanation, result + elif _is_ast_stmt(node): + mod = ast.Module([node]) + co = self._compile(mod, "exec") + try: + self.frame.exec_(co) + except Exception: + raise Failure() + return None, None + else: + raise AssertionError("can't handle %s" %(node,)) + + def _compile(self, source, mode="eval"): + return compile(source, "<assertion interpretation>", mode) + + def visit_Expr(self, expr): + return self.visit(expr.value) + + def visit_Module(self, mod): + for stmt in mod.body: + self.visit(stmt) + + def visit_Name(self, name): + explanation, result = self.generic_visit(name) + # See if the name is local. + source = "%r in locals() is not globals()" % (name.id,) + co = self._compile(source) + try: + local = self.frame.eval(co) + except Exception: + # have to assume it isn't + local = None + if local is None or not self.frame.is_true(local): + return name.id, result + return explanation, result + + def visit_Compare(self, comp): + left = comp.left + left_explanation, left_result = self.visit(left) + for op, next_op in zip(comp.ops, comp.comparators): + next_explanation, next_result = self.visit(next_op) + op_symbol = operator_map[op.__class__] + explanation = "%s %s %s" % (left_explanation, op_symbol, + next_explanation) + source = "__exprinfo_left %s __exprinfo_right" % (op_symbol,) + co = self._compile(source) + try: + result = self.frame.eval(co, __exprinfo_left=left_result, + __exprinfo_right=next_result) + except Exception: + raise Failure(explanation) + try: + if not self.frame.is_true(result): + break + except KeyboardInterrupt: + raise + except: + break + left_explanation, left_result = next_explanation, next_result + + if util._reprcompare is not None: + res = util._reprcompare(op_symbol, left_result, next_result) + if res: + explanation = res + return explanation, result + + def visit_BoolOp(self, boolop): + is_or = isinstance(boolop.op, ast.Or) + explanations = [] + for operand in boolop.values: + explanation, result = self.visit(operand) + explanations.append(explanation) + if result == is_or: + break + name = is_or and " or " or " and " + explanation = "(" + name.join(explanations) + ")" + return explanation, result + + def visit_UnaryOp(self, unary): + pattern = unary_map[unary.op.__class__] + operand_explanation, operand_result = self.visit(unary.operand) + explanation = pattern % (operand_explanation,) + co = self._compile(pattern % ("__exprinfo_expr",)) + try: + result = self.frame.eval(co, __exprinfo_expr=operand_result) + except Exception: + raise Failure(explanation) + return explanation, result + + def visit_BinOp(self, binop): + left_explanation, left_result = self.visit(binop.left) + right_explanation, right_result = self.visit(binop.right) + symbol = operator_map[binop.op.__class__] + explanation = "(%s %s %s)" % (left_explanation, symbol, + right_explanation) + source = "__exprinfo_left %s __exprinfo_right" % (symbol,) + co = self._compile(source) + try: + result = self.frame.eval(co, __exprinfo_left=left_result, + __exprinfo_right=right_result) + except Exception: + raise Failure(explanation) + return explanation, result + + def visit_Call(self, call): + func_explanation, func = self.visit(call.func) + arg_explanations = [] + ns = {"__exprinfo_func" : func} + arguments = [] + for arg in call.args: + arg_explanation, arg_result = self.visit(arg) + if isinstance(arg, _Starred): + arg_name = "__exprinfo_star" + ns[arg_name] = arg_result + arguments.append("*%s" % (arg_name,)) + arg_explanations.append("*%s" % (arg_explanation,)) + else: + arg_name = "__exprinfo_%s" % (len(ns),) + ns[arg_name] = arg_result + arguments.append(arg_name) + arg_explanations.append(arg_explanation) + for keyword in call.keywords: + arg_explanation, arg_result = self.visit(keyword.value) + if keyword.arg: + arg_name = "__exprinfo_%s" % (len(ns),) + keyword_source = "%s=%%s" % (keyword.arg) + arguments.append(keyword_source % (arg_name,)) + arg_explanations.append(keyword_source % (arg_explanation,)) + else: + arg_name = "__exprinfo_kwds" + arguments.append("**%s" % (arg_name,)) + arg_explanations.append("**%s" % (arg_explanation,)) + + ns[arg_name] = arg_result + + if getattr(call, 'starargs', None): + arg_explanation, arg_result = self.visit(call.starargs) + arg_name = "__exprinfo_star" + ns[arg_name] = arg_result + arguments.append("*%s" % (arg_name,)) + arg_explanations.append("*%s" % (arg_explanation,)) + + if getattr(call, 'kwargs', None): + arg_explanation, arg_result = self.visit(call.kwargs) + arg_name = "__exprinfo_kwds" + ns[arg_name] = arg_result + arguments.append("**%s" % (arg_name,)) + arg_explanations.append("**%s" % (arg_explanation,)) + args_explained = ", ".join(arg_explanations) + explanation = "%s(%s)" % (func_explanation, args_explained) + args = ", ".join(arguments) + source = "__exprinfo_func(%s)" % (args,) + co = self._compile(source) + try: + result = self.frame.eval(co, **ns) + except Exception: + raise Failure(explanation) + pattern = "%s\n{%s = %s\n}" + rep = self.frame.repr(result) + explanation = pattern % (rep, rep, explanation) + return explanation, result + + def _is_builtin_name(self, name): + pattern = "%r not in globals() and %r not in locals()" + source = pattern % (name.id, name.id) + co = self._compile(source) + try: + return self.frame.eval(co) + except Exception: + return False + + def visit_Attribute(self, attr): + if not isinstance(attr.ctx, ast.Load): + return self.generic_visit(attr) + source_explanation, source_result = self.visit(attr.value) + explanation = "%s.%s" % (source_explanation, attr.attr) + source = "__exprinfo_expr.%s" % (attr.attr,) + co = self._compile(source) + try: + try: + result = self.frame.eval(co, __exprinfo_expr=source_result) + except AttributeError: + # Maybe the attribute name needs to be mangled? + if not attr.attr.startswith("__") or attr.attr.endswith("__"): + raise + source = "getattr(__exprinfo_expr.__class__, '__name__', '')" + co = self._compile(source) + class_name = self.frame.eval(co, __exprinfo_expr=source_result) + mangled_attr = "_" + class_name + attr.attr + source = "__exprinfo_expr.%s" % (mangled_attr,) + co = self._compile(source) + result = self.frame.eval(co, __exprinfo_expr=source_result) + except Exception: + raise Failure(explanation) + explanation = "%s\n{%s = %s.%s\n}" % (self.frame.repr(result), + self.frame.repr(result), + source_explanation, attr.attr) + # Check if the attr is from an instance. + source = "%r in getattr(__exprinfo_expr, '__dict__', {})" + source = source % (attr.attr,) + co = self._compile(source) + try: + from_instance = self.frame.eval(co, __exprinfo_expr=source_result) + except Exception: + from_instance = None + if from_instance is None or self.frame.is_true(from_instance): + rep = self.frame.repr(result) + pattern = "%s\n{%s = %s\n}" + explanation = pattern % (rep, rep, explanation) + return explanation, result + + def visit_Assert(self, assrt): + test_explanation, test_result = self.visit(assrt.test) + explanation = "assert %s" % (test_explanation,) + if not self.frame.is_true(test_result): + try: + raise util.BuiltinAssertionError + except Exception: + raise Failure(explanation) + return explanation, test_result + + def visit_Assign(self, assign): + value_explanation, value_result = self.visit(assign.value) + explanation = "... = %s" % (value_explanation,) + name = ast.Name("__exprinfo_expr", ast.Load(), + lineno=assign.value.lineno, + col_offset=assign.value.col_offset) + new_assign = ast.Assign(assign.targets, name, lineno=assign.lineno, + col_offset=assign.col_offset) + mod = ast.Module([new_assign]) + co = self._compile(mod, "exec") + try: + self.frame.exec_(co, __exprinfo_expr=value_result) + except Exception: + raise Failure(explanation) + return explanation, value_result + |