"""Rewrite assertion AST to produce nice error messages"""
import ast
import errno
import itertools
import imp
import marshal
import os
import re
import struct
import sys
import types
import py
from _pytest.assertion import util
# pytest caches rewritten pycs in __pycache__.
if hasattr(imp, "get_tag"):
PYTEST_TAG = imp.get_tag() + "-PYTEST"
else:
if hasattr(sys, "pypy_version_info"):
impl = "pypy"
elif sys.platform == "java":
impl = "jython"
else:
impl = "cpython"
ver = sys.version_info
PYTEST_TAG = "%s-%s%s-PYTEST" % (impl, ver[0], ver[1])
del ver, impl
PYC_EXT = ".py" + (__debug__ and "c" or "o")
PYC_TAIL = "." + PYTEST_TAG + PYC_EXT
REWRITE_NEWLINES = sys.version_info[:2] != (2, 7) and sys.version_info < (3, 2)
ASCII_IS_DEFAULT_ENCODING = sys.version_info[0] < 3
if sys.version_info >= (3,5):
ast_Call = ast.Call
else:
ast_Call = lambda a,b,c: ast.Call(a, b, c, None, None)
class AssertionRewritingHook(object):
"""PEP302 Import hook which rewrites asserts."""
def __init__(self):
self.session = None
self.modules = {}
self._register_with_pkg_resources()
def set_session(self, session):
self.fnpats = session.config.getini("python_files")
self.session = session
def find_module(self, name, path=None):
if self.session is None:
return None
sess = self.session
state = sess.config._assertstate
state.trace("find_module called for: %s" % name)
names = name.rsplit(".", 1)
lastname = names[-1]
pth = None
if path is not None:
# Starting with Python 3.3, path is a _NamespacePath(), which
# causes problems if not converted to list.
path = list(path)
if len(path) == 1:
pth = path[0]
if pth is None:
try:
fd, fn, desc = imp.find_module(lastname, path)
except ImportError:
return None
if fd is not None:
fd.close()
tp = desc[2]
if tp == imp.PY_COMPILED:
if hasattr(imp, "source_from_cache"):
fn = imp.source_from_cache(fn)
else:
fn = fn[:-1]
elif tp != imp.PY_SOURCE:
# Don't know what this is.
return None
else:
fn = os.path.join(pth, name.rpartition(".")[2] + ".py")
fn_pypath = py.path.local(fn)
# Is this a test file?
if not sess.isinitpath(fn):
# We have to be very careful here because imports in this code can
# trigger a cycle.
self.session = None
try:
for pat in self.fnpats:
if fn_pypath.fnmatch(pat):
state.trace("matched test file %r" % (fn,))
break
else:
return None
finally:
self.session = sess
else:
state.trace("matched test file (was specified on cmdline): %r" %
(fn,))
# The requested module looks like a test file, so rewrite it. This is
# the most magical part of the process: load the source, rewrite the
# asserts, and load the rewritten source. We also cache the rewritten
# module code in a special pyc. We must be aware of the possibility of
# concurrent pytest processes rewriting and loading pycs. To avoid
# tricky race conditions, we maintain the following invariant: The
# cached pyc is always a complete, valid pyc. Operations on it must be
# atomic. POSIX's atomic rename comes in handy.
write = not sys.dont_write_bytecode
cache_dir = os.path.join(fn_pypath.dirname, "__pycache__")
if write:
try:
os.mkdir(cache_dir)
except OSError:
e = sys.exc_info()[1].errno
if e == errno.EEXIST:
# Either the __pycache__ directory already exists (the
# common case) or it's blocked by a non-dir node. In the
# latter case, we'll ignore it in _write_pyc.
pass
elif e in [errno.ENOENT, errno.ENOTDIR]:
# One of the path components was not a directory, likely
# because we're in a zip file.
write = False
elif e in [errno.EACCES, errno.EROFS, errno.EPERM]:
state.trace("read only directory: %r" % fn_pypath.dirname)
write = False
else:
raise
cache_name = fn_pypath.basename[:-3] + PYC_TAIL
pyc = os.path.join(cache_dir, cache_name)
# Notice that even if we're in a read-only directory, I'm going
# to check for a cached pyc. This may not be optimal...
co = _read_pyc(fn_pypath, pyc, state.trace)
if co is None:
state.trace("rewriting %r" % (fn,))
source_stat, co = _rewrite_test(state, fn_pypath)
if co is None:
# Probably a SyntaxError in the test.
return None
if write:
_make_rewritten_pyc(state, source_stat, pyc, co)
else:
state.trace("found cached rewritten pyc for %r" % (fn,))
self.modules[name] = co, pyc
return self
def load_module(self, name):
# If there is an existing module object named 'fullname' in
# sys.modules, the loader must use that existing module. (Otherwise,
# the reload() builtin will not work correctly.)
if name in sys.modules:
return sys.modules[name]
co, pyc = self.modules.pop(name)
# I wish I could just call imp.load_compiled here, but __file__ has to
# be set properly. In Python 3.2+, this all would be handled correctly
# by load_compiled.
mod = sys.modules[name] = imp.new_module(name)
try:
mod.__file__ = co.co_filename
# Normally, this attribute is 3.2+.
mod.__cached__ = pyc
mod.__loader__ = self
py.builtin.exec_(co, mod.__dict__)
except:
del sys.modules[name]
raise
return sys.modules[name]
def is_package(self, name):
try:
fd, fn, desc = imp.find_module(name)
except ImportError:
return False
if fd is not None:
fd.close()
tp = desc[2]
return tp == imp.PKG_DIRECTORY
@classmethod
def _register_with_pkg_resources(cls):
"""
Ensure package resources can be loaded from this loader. May be called
multiple times, as the operation is idempotent.
"""
try:
import pkg_resources
# access an attribute in case a deferred importer is present
pkg_resources.__name__
except ImportError:
return
# Since pytest tests are always located in the file system, the
# DefaultProvider is appropriate.
pkg_resources.register_loader_type(cls, pkg_resources.DefaultProvider)
def get_data(self, pathname):
"""Optional PEP302 get_data API.
"""
with open(pathname, 'rb') as f:
return f.read()
def _write_pyc(state, co, source_stat, pyc):
# Technically, we don't have to have the same pyc format as
# (C)Python, since these "pycs" should never be seen by builtin
# import. However, there's little reason deviate, and I hope
# sometime to be able to use imp.load_compiled to load them. (See
# the comment in load_module above.)
try:
fp = open(pyc, "wb")
except IOError:
err = sys.exc_info()[1].errno
state.trace("error writing pyc file at %s: errno=%s" %(pyc, err))
# we ignore any failure to write the cache file
# there are many reasons, permission-denied, __pycache__ being a
# file etc.
return False
try:
fp.write(imp.get_magic())
mtime = int(source_stat.mtime)
size = source_stat.size & 0xFFFFFFFF
fp.write(struct.pack("<ll", mtime, size))
marshal.dump(co, fp)
finally:
fp.close()
return True
RN = "\r\n".encode("utf-8")
N = "\n".encode("utf-8")
cookie_re = re.compile(r"^[ \t\f]*#.*coding[:=][ \t]*[-\w.]+")
BOM_UTF8 = '\xef\xbb\xbf'
def _rewrite_test(state, fn):
"""Try to read and rewrite *fn* and return the code object."""
try:
stat = fn.stat()
source = fn.read("rb")
except EnvironmentError:
return None, None
if ASCII_IS_DEFAULT_ENCODING:
# ASCII is the default encoding in Python 2. Without a coding
# declaration, Python 2 will complain about any bytes in the file
# outside the ASCII range. Sadly, this behavior does not extend to
# compile() or ast.parse(), which prefer to interpret the bytes as
# latin-1. (At least they properly handle explicit coding cookies.) To
# preserve this error behavior, we could force ast.parse() to use ASCII
# as the encoding by inserting a coding cookie. Unfortunately, that
# messes up line numbers. Thus, we have to check ourselves if anything
# is outside the ASCII range in the case no encoding is explicitly
# declared. For more context, see issue #269. Yay for Python 3 which
# gets this right.
end1 = source.find("\n")
end2 = source.find("\n", end1 + 1)
if (not source.startswith(BOM_UTF8) and
cookie_re.match(source[0:end1]) is None and
cookie_re.match(source[end1 + 1:end2]) is None):
if hasattr(state, "_indecode"):
# encodings imported us again, so don't rewrite.
return None, None
state._indecode = True
try:
try:
source.decode("ascii")
except UnicodeDecodeError:
# Let it fail in real import.
return None, None
finally:
del state._indecode
# On Python versions which are not 2.7 and less than or equal to 3.1, the
# parser expects *nix newlines.
if REWRITE_NEWLINES:
source = source.replace(RN, N) + N
try:
tree = ast.parse(source)
except SyntaxError:
# Let this pop up again in the real import.
state.trace("failed to parse: %r" % (fn,))
return None, None
rewrite_asserts(tree)
try:
co = compile(tree, fn.strpath, "exec")
except SyntaxError:
# It's possible that this error is from some bug in the
# assertion rewriting, but I don't know of a fast way to tell.
state.trace("failed to compile: %r" % (fn,))
return None, None
return stat, co
def _make_rewritten_pyc(state, source_stat, pyc, co):
"""Try to dump rewritten code to *pyc*."""
if sys.platform.startswith("win"):
# Windows grants exclusive access to open files and doesn't have atomic
# rename, so just write into the final file.
_write_pyc(state, co, source_stat, pyc)
else:
# When not on windows, assume rename is atomic. Dump the code object
# into a file specific to this process and atomically replace it.
proc_pyc = pyc + "." + str(os.getpid())
if _write_pyc(state, co, source_stat, proc_pyc):
os.rename(proc_pyc, pyc)
def _read_pyc(source, pyc, trace=lambda x: None):
"""Possibly read a pytest pyc containing rewritten code.
Return rewritten code if successful or None if not.
"""
try:
fp = open(pyc, "rb")
except IOError:
return None
with fp:
try:
mtime = int(source.mtime())
size = source.size()
data = fp.read(12)
except EnvironmentError as e:
trace('_read_pyc(%s): EnvironmentError %s' % (source, e))
return None
# Check for invalid or out of date pyc file.
if (len(data) != 12 or data[:4] != imp.get_magic() or
struct.unpack("<ll", data[4:]) != (mtime, size)):
trace('_read_pyc(%s): invalid or out of date pyc' % source)
return None
try:
co = marshal.load(fp)
except Exception as e:
trace('_read_pyc(%s): marshal.load error %s' % (source, e))
return None
if not isinstance(co, types.CodeType):
trace('_read_pyc(%s): not a code object' % source)
return None
return co
def rewrite_asserts(mod):
"""Rewrite the assert statements in mod."""
AssertionRewriter().run(mod)
def _saferepr(obj):
"""Get a safe repr of an object for assertion error messages.
The assertion formatting (util.format_explanation()) requires
newlines to be escaped since they are a special character for it.
Normally assertion.util.format_explanation() does this but for a
custom repr it is possible to contain one of the special escape
sequences, especially '\n{' and '\n}' are likely to be present in
JSON reprs.
"""
repr = py.io.saferepr(obj)
if py.builtin._istext(repr):
t = py.builtin.text
else:
t = py.builtin.bytes
return repr.replace(t("\n"), t("\\n"))
from _pytest.assertion.util import format_explanation as _format_explanation # noqa
def _format_assertmsg(obj):
"""Format the custom assertion message given.
For strings this simply replaces newlines with '\n~' so that
util.format_explanation() will preserve them instead of escaping
newlines. For other objects py.io.saferepr() is used first.
"""
# reprlib appears to have a bug which means that if a string
# contains a newline it gets escaped, however if an object has a
# .__repr__() which contains newlines it does not get escaped.
# However in either case we want to preserve the newline.
if py.builtin._istext(obj) or py.builtin._isbytes(obj):
s = obj
is_repr = False
else:
s = py.io.saferepr(obj)
is_repr = True
if py.builtin._istext(s):
t = py.builtin.text
else:
t = py.builtin.bytes
s = s.replace(t("\n"), t("\n~")).replace(t("%"), t("%%"))
if is_repr:
s = s.replace(t("\\n"), t("\n~"))
return s
def _should_repr_global_name(obj):
return not hasattr(obj, "__name__") and not py.builtin.callable(obj)
def _format_boolop(explanations, is_or):
explanation = "(" + (is_or and " or " or " and ").join(explanations) + ")"
if py.builtin._istext(explanation):
t = py.builtin.text
else:
t = py.builtin.bytes
return explanation.replace(t('%'), t('%%'))
def _call_reprcompare(ops, results, expls, each_obj):
for i, res, expl in zip(range(len(ops)), results, expls):
try:
done = not res
except Exception:
done = True
if done:
break
if util._reprcompare is not None:
custom = util._reprcompare(ops[i], each_obj[i], each_obj[i + 1])
if custom is not None:
return custom
return expl
unary_map = {
ast.Not: "not %s",
ast.Invert: "~%s",
ast.USub: "-%s",
ast.UAdd: "+%s"
}
binop_map = {
ast.BitOr: "|",
ast.BitXor: "^",
ast.BitAnd: "&",
ast.LShift: "<<",
ast.RShift: ">>",
ast.Add: "+",
ast.Sub: "-",
ast.Mult: "*",
ast.Div: "/",
ast.FloorDiv: "//",
ast.Mod: "%%", # escaped for string formatting
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"
}
# Python 3.5+ compatibility
try:
binop_map[ast.MatMult] = "@"
except AttributeError:
pass
# Python 3.4+ compatibility
if hasattr(ast, "NameConstant"):
_NameConstant = ast.NameConstant
else:
def _NameConstant(c):
return ast.Name(str(c), ast.Load())
def set_location(node, lineno, col_offset):
"""Set node location information recursively."""
def _fix(node, lineno, col_offset):
if "lineno" in node._attributes:
node.lineno = lineno
if "col_offset" in node._attributes:
node.col_offset = col_offset
for child in ast.iter_child_nodes(node):
_fix(child, lineno, col_offset)
_fix(node, lineno, col_offset)
return node
class AssertionRewriter(ast.NodeVisitor):
"""Assertion rewriting implementation.
The main entrypoint is to call .run() with an ast.Module instance,
this will then find all the assert statements and re-write them to
provide intermediate values and a detailed assertion error. See
http://pybites.blogspot.be/2011/07/behind-scenes-of-pytests-new-assertion.html
for an overview of how this works.
The entry point here is .run() which will iterate over all the
statements in an ast.Module and for each ast.Assert statement it
finds call .visit() with it. Then .visit_Assert() takes over and
is responsible for creating new ast statements to replace the
original assert statement: it re-writes the test of an assertion
to provide intermediate values and replace it with an if statement
which raises an assertion error with a detailed explanation in
case the expression is false.
For this .visit_Assert() uses the visitor pattern to visit all the
AST nodes of the ast.Assert.test field, each visit call returning
an AST node and the corresponding explanation string. During this
state is kept in several instance attributes:
:statements: All the AST statements which will replace the assert
statement.
:variables: This is populated by .variable() with each variable
used by the statements so that they can all be set to None at
the end of the statements.
:variable_counter: Counter to create new unique variables needed
by statements. Variables are created using .variable() and
have the form of "@py_assert0".
:on_failure: The AST statements which will be executed if the
assertion test fails. This is the code which will construct
the failure message and raises the AssertionError.
:explanation_specifiers: A dict filled by .explanation_param()
with %-formatting placeholders and their corresponding
expressions to use in the building of an assertion message.
This is used by .pop_format_context() to build a message.
:stack: A stack of the explanation_specifiers dicts maintained by
.push_format_context() and .pop_format_context() which allows
to build another %-formatted string while already building one.
This state is reset on every new assert statement visited and used
by the other visitors.
"""
def run(self, mod):
"""Find all assert statements in *mod* and rewrite them."""
if not mod.body:
# Nothing to do.
return
# Insert some special imports at the top of the module but after any
# docstrings and __future__ imports.
aliases = [ast.alias(py.builtin.builtins.__name__, "@py_builtins"),
ast.alias("_pytest.assertion.rewrite", "@pytest_ar")]
expect_docstring = True
pos = 0
lineno = 0
for item in mod.body:
if (expect_docstring and isinstance(item, ast.Expr) and
isinstance(item.value, ast.Str)):
doc = item.value.s
if "PYTEST_DONT_REWRITE" in doc:
# The module has disabled assertion rewriting.
return
lineno += len(doc) - 1
expect_docstring = False
elif (not isinstance(item, ast.ImportFrom) or item.level > 0 or
item.module != "__future__"):
lineno = item.lineno
break
pos += 1
imports = [ast.Import([alias], lineno=lineno, col_offset=0)
for alias in aliases]
mod.body[pos:pos] = imports
# Collect asserts.
nodes = [mod]
while nodes:
node = nodes.pop()
for name, field in ast.iter_fields(node):
if isinstance(field, list):
new = []
for i, child in enumerate(field):
if isinstance(child, ast.Assert):
# Transform assert.
new.extend(self.visit(child))
else:
new.append(child)
if isinstance(child, ast.AST):
nodes.append(child)
setattr(node, name, new)
elif (isinstance(field, ast.AST) and
# Don't recurse into expressions as they can't contain
# asserts.
not isinstance(field, ast.expr)):
nodes.append(field)
def variable(self):
"""Get a new variable."""
# Use a character invalid in python identifiers to avoid clashing.
name = "@py_assert" + str(next(self.variable_counter))
self.variables.append(name)
return name
def assign(self, expr):
"""Give *expr* a name."""
name = self.variable()
self.statements.append(ast.Assign([ast.Name(name, ast.Store())], expr))
return ast.Name(name, ast.Load())
def display(self, expr):
"""Call py.io.saferepr on the expression."""
return self.helper("saferepr", expr)
def helper(self, name, *args):
"""Call a helper in this module."""
py_name = ast.Name("@pytest_ar", ast.Load())
attr = ast.Attribute(py_name, "_" + name, ast.Load())
return ast_Call(attr, list(args), [])
def builtin(self, name):
"""Return the builtin called *name*."""
builtin_name = ast.Name("@py_builtins", ast.Load())
return ast.Attribute(builtin_name, name, ast.Load())
def explanation_param(self, expr):
"""Return a new named %-formatting placeholder for expr.
This creates a %-formatting placeholder for expr in the
current formatting context, e.g. ``%(py0)s``. The placeholder
and expr are placed in the current format context so that it
can be used on the next call to .pop_format_context().
"""
specifier = "py" + str(next(self.variable_counter))
self.explanation_specifiers[specifier] = expr
return "%(" + specifier + ")s"
def push_format_context(self):
"""Create a new formatting context.
The format context is used for when an explanation wants to
have a variable value formatted in the assertion message. In
this case the value required can be added using
.explanation_param(). Finally .pop_format_context() is used
to format a string of %-formatted values as added by
.explanation_param().
"""
self.explanation_specifiers = {}
self.stack.append(self.explanation_specifiers)
def pop_format_context(self, expl_expr):
"""Format the %-formatted string with current format context.
The expl_expr should be an ast.Str instance constructed from
the %-placeholders created by .explanation_param(). This will
add the required code to format said string to .on_failure and
return the ast.Name instance of the formatted string.
"""
current = self.stack.pop()
if self.stack:
self.explanation_specifiers = self.stack[-1]
keys = [ast.Str(key) for key in current.keys()]
format_dict = ast.Dict(keys, list(current.values()))
form = ast.BinOp(expl_expr, ast.Mod(), format_dict)
name = "@py_format" + str(next(self.variable_counter))
self.on_failure.append(ast.Assign([ast.Name(name, ast.Store())], form))
return ast.Name(name, ast.Load())
def generic_visit(self, node):
"""Handle expressions we don't have custom code for."""
assert isinstance(node, ast.expr)
res = self.assign(node)
return res, self.explanation_param(self.display(res))
def visit_Assert(self, assert_):
"""Return the AST statements to replace the ast.Assert instance.
This re-writes the test of an assertion to provide
intermediate values and replace it with an if statement which
raises an assertion error with a detailed explanation in case
the expression is false.
"""
self.statements = []
self.variables = []
self.variable_counter = itertools.count()
self.stack = []
self.on_failure = []
self.push_format_context()
# Rewrite assert into a bunch of statements.
top_condition, explanation = self.visit(assert_.test)
# Create failure message.
body = self.on_failure
negation = ast.UnaryOp(ast.Not(), top_condition)
self.statements.append(ast.If(negation, body, []))
if assert_.msg:
assertmsg = self.helper('format_assertmsg', assert_.msg)
explanation = "\n>assert " + explanation
else:
assertmsg = ast.Str("")
explanation = "assert " + explanation
template = ast.BinOp(assertmsg, ast.Add(), ast.Str(explanation))
msg = self.pop_format_context(template)
fmt = self.helper("format_explanation", msg)
err_name = ast.Name("AssertionError", ast.Load())
exc = ast_Call(err_name, [fmt], [])
if sys.version_info[0] >= 3:
raise_ = ast.Raise(exc, None)
else:
raise_ = ast.Raise(exc, None, None)
body.append(raise_)
# Clear temporary variables by setting them to None.
if self.variables:
variables = [ast.Name(name, ast.Store())
for name in self.variables]
clear = ast.Assign(variables, _NameConstant(None))
self.statements.append(clear)
# Fix line numbers.
for stmt in self.statements:
set_location(stmt, assert_.lineno, assert_.col_offset)
return self.statements
def visit_Name(self, name):
# Display the repr of the name if it's a local variable or
# _should_repr_global_name() thinks it's acceptable.
locs = ast_Call(self.builtin("locals"), [], [])
inlocs = ast.Compare(ast.Str(name.id), [ast.In()], [locs])
dorepr = self.helper("should_repr_global_name", name)
test = ast.BoolOp(ast.Or(), [inlocs, dorepr])
expr = ast.IfExp(test, self.display(name), ast.Str(name.id))
return name, self.explanation_param(expr)
def visit_BoolOp(self, boolop):
res_var = self.variable()
expl_list = self.assign(ast.List([], ast.Load()))
app = ast.Attribute(expl_list, "append", ast.Load())
is_or = int(isinstance(boolop.op, ast.Or))
body = save = self.statements
fail_save = self.on_failure
levels = len(boolop.values) - 1
self.push_format_context()
# Process each operand, short-circuting if needed.
for i, v in enumerate(boolop.values):
if i:
fail_inner = []
# cond is set in a prior loop iteration below
self.on_failure.append(ast.If(cond, fail_inner, [])) # noqa
self.on_failure = fail_inner
self.push_format_context()
res, expl = self.visit(v)
body.append(ast.Assign([ast.Name(res_var, ast.Store())], res))
expl_format = self.pop_format_context(ast.Str(expl))
call = ast_Call(app, [expl_format], [])
self.on_failure.append(ast.Expr(call))
if i < levels:
cond = res
if is_or:
cond = ast.UnaryOp(ast.Not(), cond)
inner = []
self.statements.append(ast.If(cond, inner, []))
self.statements = body = inner
self.statements = save
self.on_failure = fail_save
expl_template = self.helper("format_boolop", expl_list, ast.Num(is_or))
expl = self.pop_format_context(expl_template)
return ast.Name(res_var, ast.Load()), self.explanation_param(expl)
def visit_UnaryOp(self, unary):
pattern = unary_map[unary.op.__class__]
operand_res, operand_expl = self.visit(unary.operand)
res = self.assign(ast.UnaryOp(unary.op, operand_res))
return res, pattern % (operand_expl,)
def visit_BinOp(self, binop):
symbol = binop_map[binop.op.__class__]
left_expr, left_expl = self.visit(binop.left)
right_expr, right_expl = self.visit(binop.right)
explanation = "(%s %s %s)" % (left_expl, symbol, right_expl)
res = self.assign(ast.BinOp(left_expr, binop.op, right_expr))
return res, explanation
def visit_Call_35(self, call):
"""
visit `ast.Call` nodes on Python3.5 and after
"""
new_func, func_expl = self.visit(call.func)
arg_expls = []
new_args = []
new_kwargs = []
for arg in call.args:
res, expl = self.visit(arg)
arg_expls.append(expl)
new_args.append(res)
for keyword in call.keywords:
res, expl = self.visit(keyword.value)
new_kwargs.append(ast.keyword(keyword.arg, res))
if keyword.arg:
arg_expls.append(keyword.arg + "=" + expl)
else: ## **args have `arg` keywords with an .arg of None
arg_expls.append("**" + expl)
expl = "%s(%s)" % (func_expl, ', '.join(arg_expls))
new_call = ast.Call(new_func, new_args, new_kwargs)
res = self.assign(new_call)
res_expl = self.explanation_param(self.display(res))
outer_expl = "%s\n{%s = %s\n}" % (res_expl, res_expl, expl)
return res, outer_expl
def visit_Starred(self, starred):
# From Python 3.5, a Starred node can appear in a function call
res, expl = self.visit(starred.value)
return starred, '*' + expl
def visit_Call_legacy(self, call):
"""
visit `ast.Call nodes on 3.4 and below`
"""
new_func, func_expl = self.visit(call.func)
arg_expls = []
new_args = []
new_kwargs = []
new_star = new_kwarg = None
for arg in call.args:
res, expl = self.visit(arg)
new_args.append(res)
arg_expls.append(expl)
for keyword in call.keywords:
res, expl = self.visit(keyword.value)
new_kwargs.append(ast.keyword(keyword.arg, res))
arg_expls.append(keyword.arg + "=" + expl)
if call.starargs:
new_star, expl = self.visit(call.starargs)
arg_expls.append("*" + expl)
if call.kwargs:
new_kwarg, expl = self.visit(call.kwargs)
arg_expls.append("**" + expl)
expl = "%s(%s)" % (func_expl, ', '.join(arg_expls))
new_call = ast.Call(new_func, new_args, new_kwargs,
new_star, new_kwarg)
res = self.assign(new_call)
res_expl = self.explanation_param(self.display(res))
outer_expl = "%s\n{%s = %s\n}" % (res_expl, res_expl, expl)
return res, outer_expl
# ast.Call signature changed on 3.5,
# conditionally change which methods is named
# visit_Call depending on Python version
if sys.version_info >= (3, 5):
visit_Call = visit_Call_35
else:
visit_Call = visit_Call_legacy
def visit_Attribute(self, attr):
if not isinstance(attr.ctx, ast.Load):
return self.generic_visit(attr)
value, value_expl = self.visit(attr.value)
res = self.assign(ast.Attribute(value, attr.attr, ast.Load()))
res_expl = self.explanation_param(self.display(res))
pat = "%s\n{%s = %s.%s\n}"
expl = pat % (res_expl, res_expl, value_expl, attr.attr)
return res, expl
def visit_Compare(self, comp):
self.push_format_context()
left_res, left_expl = self.visit(comp.left)
res_variables = [self.variable() for i in range(len(comp.ops))]
load_names = [ast.Name(v, ast.Load()) for v in res_variables]
store_names = [ast.Name(v, ast.Store()) for v in res_variables]
it = zip(range(len(comp.ops)), comp.ops, comp.comparators)
expls = []
syms = []
results = [left_res]
for i, op, next_operand in it:
next_res, next_expl = self.visit(next_operand)
results.append(next_res)
sym = binop_map[op.__class__]
syms.append(ast.Str(sym))
expl = "%s %s %s" % (left_expl, sym, next_expl)
expls.append(ast.Str(expl))
res_expr = ast.Compare(left_res, [op], [next_res])
self.statements.append(ast.Assign([store_names[i]], res_expr))
left_res, left_expl = next_res, next_expl
# Use pytest.assertion.util._reprcompare if that's available.
expl_call = self.helper("call_reprcompare",
ast.Tuple(syms, ast.Load()),
ast.Tuple(load_names, ast.Load()),
ast.Tuple(expls, ast.Load()),
ast.Tuple(results, ast.Load()))
if len(comp.ops) > 1:
res = ast.BoolOp(ast.And(), load_names)
else:
res = load_names[0]
return res, self.explanation_param(self.pop_format_context(expl_call))