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Diffstat (limited to 'python/pytest/_pytest/assertion/__init__.py')
| -rw-r--r-- | python/pytest/_pytest/assertion/__init__.py | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/python/pytest/_pytest/assertion/__init__.py b/python/pytest/_pytest/assertion/__init__.py new file mode 100644 index 000000000..6921deb2a --- /dev/null +++ b/python/pytest/_pytest/assertion/__init__.py @@ -0,0 +1,176 @@ +""" +support for presenting detailed information in failing assertions. +""" +import py +import os +import sys +from _pytest.monkeypatch import monkeypatch +from _pytest.assertion import util + + +def pytest_addoption(parser): + group = parser.getgroup("debugconfig") + group.addoption('--assert', + action="store", + dest="assertmode", + choices=("rewrite", "reinterp", "plain",), + default="rewrite", + metavar="MODE", + help="""control assertion debugging tools. 'plain' + performs no assertion debugging. 'reinterp' + reinterprets assert statements after they failed + to provide assertion expression information. + 'rewrite' (the default) rewrites assert + statements in test modules on import to + provide assert expression information. """) + group.addoption('--no-assert', + action="store_true", + default=False, + dest="noassert", + help="DEPRECATED equivalent to --assert=plain") + group.addoption('--nomagic', '--no-magic', + action="store_true", + default=False, + help="DEPRECATED equivalent to --assert=plain") + + +class AssertionState: + """State for the assertion plugin.""" + + def __init__(self, config, mode): + self.mode = mode + self.trace = config.trace.root.get("assertion") + + +def pytest_configure(config): + mode = config.getvalue("assertmode") + if config.getvalue("noassert") or config.getvalue("nomagic"): + mode = "plain" + if mode == "rewrite": + try: + import ast # noqa + except ImportError: + mode = "reinterp" + else: + # Both Jython and CPython 2.6.0 have AST bugs that make the + # assertion rewriting hook malfunction. + if (sys.platform.startswith('java') or + sys.version_info[:3] == (2, 6, 0)): + mode = "reinterp" + if mode != "plain": + _load_modules(mode) + m = monkeypatch() + config._cleanup.append(m.undo) + m.setattr(py.builtin.builtins, 'AssertionError', + reinterpret.AssertionError) # noqa + hook = None + if mode == "rewrite": + hook = rewrite.AssertionRewritingHook() # noqa + sys.meta_path.insert(0, hook) + warn_about_missing_assertion(mode) + config._assertstate = AssertionState(config, mode) + config._assertstate.hook = hook + config._assertstate.trace("configured with mode set to %r" % (mode,)) + def undo(): + hook = config._assertstate.hook + if hook is not None and hook in sys.meta_path: + sys.meta_path.remove(hook) + config.add_cleanup(undo) + + +def pytest_collection(session): + # this hook is only called when test modules are collected + # so for example not in the master process of pytest-xdist + # (which does not collect test modules) + hook = session.config._assertstate.hook + if hook is not None: + hook.set_session(session) + + +def _running_on_ci(): + """Check if we're currently running on a CI system.""" + env_vars = ['CI', 'BUILD_NUMBER'] + return any(var in os.environ for var in env_vars) + + +def pytest_runtest_setup(item): + """Setup the pytest_assertrepr_compare hook + + The newinterpret and rewrite modules 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. + """ + def callbinrepr(op, left, right): + """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 dropped unless -vv was used or + running on a CI. + * 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 = item.ihook.pytest_assertrepr_compare( + config=item.config, op=op, left=left, right=right) + for new_expl in hook_result: + if new_expl: + if (sum(len(p) for p in new_expl[1:]) > 80*8 and + item.config.option.verbose < 2 and + not _running_on_ci()): + show_max = 10 + truncated_lines = len(new_expl) - show_max + new_expl[show_max:] = [py.builtin._totext( + 'Detailed information truncated (%d more lines)' + ', use "-vv" to show' % truncated_lines)] + new_expl = [line.replace("\n", "\\n") for line in new_expl] + res = py.builtin._totext("\n~").join(new_expl) + if item.config.getvalue("assertmode") == "rewrite": + res = res.replace("%", "%%") + return res + util._reprcompare = callbinrepr + + +def pytest_runtest_teardown(item): + util._reprcompare = None + + +def pytest_sessionfinish(session): + hook = session.config._assertstate.hook + if hook is not None: + hook.session = None + + +def _load_modules(mode): + """Lazily import assertion related code.""" + global rewrite, reinterpret + from _pytest.assertion import reinterpret # noqa + if mode == "rewrite": + from _pytest.assertion import rewrite # noqa + + +def warn_about_missing_assertion(mode): + try: + assert False + except AssertionError: + pass + else: + if mode == "rewrite": + specifically = ("assertions which are not in test modules " + "will be ignored") + else: + specifically = "failing tests may report as passing" + + sys.stderr.write("WARNING: " + specifically + + " because assert statements are not executed " + "by the underlying Python interpreter " + "(are you using python -O?)\n") + + +# Expose this plugin's implementation for the pytest_assertrepr_compare hook +pytest_assertrepr_compare = util.assertrepr_compare |