180 lines
6.3 KiB
Python
180 lines
6.3 KiB
Python
"""Support for presenting detailed information in failing assertions."""
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import sys
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from typing import Any
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from typing import Generator
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from typing import List
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from typing import Optional
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from typing import TYPE_CHECKING
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from _pytest.assertion import rewrite
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from _pytest.assertion import truncate
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from _pytest.assertion import util
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from _pytest.assertion.rewrite import assertstate_key
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from _pytest.config import Config
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from _pytest.config import hookimpl
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from _pytest.config.argparsing import Parser
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from _pytest.nodes import Item
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if TYPE_CHECKING:
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from _pytest.main import Session
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def pytest_addoption(parser: Parser) -> None:
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group = parser.getgroup("debugconfig")
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group.addoption(
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"--assert",
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action="store",
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dest="assertmode",
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choices=("rewrite", "plain"),
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default="rewrite",
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metavar="MODE",
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help=(
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"Control assertion debugging tools.\n"
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"'plain' performs no assertion debugging.\n"
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"'rewrite' (the default) rewrites assert statements in test modules"
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" on import to provide assert expression information."
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),
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)
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parser.addini(
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"enable_assertion_pass_hook",
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type="bool",
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default=False,
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help="Enables the pytest_assertion_pass hook."
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"Make sure to delete any previously generated pyc cache files.",
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)
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def register_assert_rewrite(*names: str) -> None:
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"""Register one or more module names to be rewritten on import.
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This function will make sure that this module or all modules inside
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the package will get their assert statements rewritten.
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Thus you should make sure to call this before the module is
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actually imported, usually in your __init__.py if you are a plugin
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using a package.
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:raises TypeError: If the given module names are not strings.
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"""
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for name in names:
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if not isinstance(name, str):
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msg = "expected module names as *args, got {0} instead" # type: ignore[unreachable]
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raise TypeError(msg.format(repr(names)))
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for hook in sys.meta_path:
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if isinstance(hook, rewrite.AssertionRewritingHook):
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importhook = hook
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break
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else:
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# TODO(typing): Add a protocol for mark_rewrite() and use it
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# for importhook and for PytestPluginManager.rewrite_hook.
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importhook = DummyRewriteHook() # type: ignore
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importhook.mark_rewrite(*names)
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class DummyRewriteHook:
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"""A no-op import hook for when rewriting is disabled."""
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def mark_rewrite(self, *names: str) -> None:
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pass
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class AssertionState:
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"""State for the assertion plugin."""
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def __init__(self, config: Config, mode) -> None:
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self.mode = mode
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self.trace = config.trace.root.get("assertion")
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self.hook: Optional[rewrite.AssertionRewritingHook] = None
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def install_importhook(config: Config) -> rewrite.AssertionRewritingHook:
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"""Try to install the rewrite hook, raise SystemError if it fails."""
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config._store[assertstate_key] = AssertionState(config, "rewrite")
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config._store[assertstate_key].hook = hook = rewrite.AssertionRewritingHook(config)
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sys.meta_path.insert(0, hook)
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config._store[assertstate_key].trace("installed rewrite import hook")
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def undo() -> None:
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hook = config._store[assertstate_key].hook
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if hook is not None and hook in sys.meta_path:
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sys.meta_path.remove(hook)
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config.add_cleanup(undo)
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return hook
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def pytest_collection(session: "Session") -> None:
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# This hook is only called when test modules are collected
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# so for example not in the master process of pytest-xdist
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# (which does not collect test modules).
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assertstate = session.config._store.get(assertstate_key, None)
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if assertstate:
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if assertstate.hook is not None:
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assertstate.hook.set_session(session)
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@hookimpl(tryfirst=True, hookwrapper=True)
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def pytest_runtest_protocol(item: Item) -> Generator[None, None, None]:
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"""Setup the pytest_assertrepr_compare and pytest_assertion_pass hooks.
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The rewrite module will use util._reprcompare if it exists to use custom
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reporting via the pytest_assertrepr_compare hook. This sets up this custom
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comparison for the test.
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"""
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ihook = item.ihook
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def callbinrepr(op, left: object, right: object) -> Optional[str]:
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"""Call the pytest_assertrepr_compare hook and prepare the result.
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This uses the first result from the hook and then ensures the
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following:
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* Overly verbose explanations are truncated unless configured otherwise
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(eg. if running in verbose mode).
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* Embedded newlines are escaped to help util.format_explanation()
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later.
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* If the rewrite mode is used embedded %-characters are replaced
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to protect later % formatting.
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The result can be formatted by util.format_explanation() for
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pretty printing.
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"""
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hook_result = ihook.pytest_assertrepr_compare(
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config=item.config, op=op, left=left, right=right
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)
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for new_expl in hook_result:
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if new_expl:
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new_expl = truncate.truncate_if_required(new_expl, item)
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new_expl = [line.replace("\n", "\\n") for line in new_expl]
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res = "\n~".join(new_expl)
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if item.config.getvalue("assertmode") == "rewrite":
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res = res.replace("%", "%%")
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return res
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return None
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saved_assert_hooks = util._reprcompare, util._assertion_pass
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util._reprcompare = callbinrepr
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if ihook.pytest_assertion_pass.get_hookimpls():
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def call_assertion_pass_hook(lineno: int, orig: str, expl: str) -> None:
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ihook.pytest_assertion_pass(item=item, lineno=lineno, orig=orig, expl=expl)
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util._assertion_pass = call_assertion_pass_hook
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yield
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util._reprcompare, util._assertion_pass = saved_assert_hooks
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def pytest_sessionfinish(session: "Session") -> None:
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assertstate = session.config._store.get(assertstate_key, None)
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if assertstate:
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if assertstate.hook is not None:
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assertstate.hook.set_session(None)
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def pytest_assertrepr_compare(
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config: Config, op: str, left: Any, right: Any
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) -> Optional[List[str]]:
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return util.assertrepr_compare(config=config, op=op, left=left, right=right)
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