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