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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /python/pytest/_pytest/assertion/rewrite.py
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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-rw-r--r--python/pytest/_pytest/assertion/rewrite.py885
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diff --git a/python/pytest/_pytest/assertion/rewrite.py b/python/pytest/_pytest/assertion/rewrite.py
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+++ b/python/pytest/_pytest/assertion/rewrite.py
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+"""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))