test_ok2/testing/test_recwarn.py

import warnings
import py
import pytest
from _pytest.recwarn import WarningsChecker, WarningsRecorder


def test_recwarn_functional(testdir):
    reprec = testdir.inline_runsource("""
        import warnings
        oldwarn = warnings.showwarning
        def test_method(recwarn):
            assert warnings.showwarning != oldwarn
            warnings.warn("hello")
            warn = recwarn.pop()
            assert isinstance(warn.message, UserWarning)
        def test_finalized():
            assert warnings.showwarning == oldwarn
    """)
    res = reprec.countoutcomes()
    assert tuple(res) == (2, 0, 0), res


class TestWarningsRecorderChecker(object):
    def test_recording(self, recwarn):
        showwarning = py.std.warnings.showwarning
        rec = WarningsRecorder()
        with rec:
            assert py.std.warnings.showwarning != showwarning
            assert not rec.list
            py.std.warnings.warn_explicit("hello", UserWarning, "xyz", 13)
            assert len(rec.list) == 1
            py.std.warnings.warn(DeprecationWarning("hello"))
            assert len(rec.list) == 2
            warn = rec.pop()
            assert str(warn.message) == "hello"
            l = rec.list
            rec.clear()
            assert len(rec.list) == 0
            assert l is rec.list
            pytest.raises(AssertionError, "rec.pop()")

        assert showwarning == py.std.warnings.showwarning

    def test_typechecking(self):
        with pytest.raises(TypeError):
            WarningsChecker(5)
        with pytest.raises(TypeError):
            WarningsChecker(('hi', RuntimeWarning))
        with pytest.raises(TypeError):
            WarningsChecker([DeprecationWarning, RuntimeWarning])

    def test_invalid_enter_exit(self):
        # wrap this test in WarningsRecorder to ensure warning state gets reset
        with WarningsRecorder():
            with pytest.raises(RuntimeError):
                rec = WarningsRecorder()
                rec.__exit__(None, None, None)  # can't exit before entering

            with pytest.raises(RuntimeError):
                rec = WarningsRecorder()
                with rec:
                    with rec:
                        pass  # can't enter twice

#
# ============ test pytest.deprecated_call() ==============
#

def dep(i):
    if i == 0:
        py.std.warnings.warn("is deprecated", DeprecationWarning)
    return 42

reg = {}
def dep_explicit(i):
    if i == 0:
        py.std.warnings.warn_explicit("dep_explicit", category=DeprecationWarning,
                                      filename="hello", lineno=3)

class TestDeprecatedCall(object):
    def test_deprecated_call_raises(self):
        excinfo = pytest.raises(AssertionError,
                       "pytest.deprecated_call(dep, 3)")
        assert str(excinfo).find("did not produce") != -1

    def test_deprecated_call(self):
        pytest.deprecated_call(dep, 0)

    def test_deprecated_call_ret(self):
        ret = pytest.deprecated_call(dep, 0)
        assert ret == 42

    def test_deprecated_call_preserves(self):
        onceregistry = py.std.warnings.onceregistry.copy()
        filters = py.std.warnings.filters[:]
        warn = py.std.warnings.warn
        warn_explicit = py.std.warnings.warn_explicit
        self.test_deprecated_call_raises()
        self.test_deprecated_call()
        assert onceregistry == py.std.warnings.onceregistry
        assert filters == py.std.warnings.filters
        assert warn is py.std.warnings.warn
        assert warn_explicit is py.std.warnings.warn_explicit

    def test_deprecated_explicit_call_raises(self):
        pytest.raises(AssertionError,
                       "pytest.deprecated_call(dep_explicit, 3)")

    def test_deprecated_explicit_call(self):
        pytest.deprecated_call(dep_explicit, 0)
        pytest.deprecated_call(dep_explicit, 0)


class TestWarns(object):
    def test_strings(self):
        # different messages, b/c Python suppresses multiple identical warnings
        source1 = "warnings.warn('w1', RuntimeWarning)"
        source2 = "warnings.warn('w2', RuntimeWarning)"
        source3 = "warnings.warn('w3', RuntimeWarning)"
        pytest.warns(RuntimeWarning, source1)
        pytest.raises(pytest.fail.Exception,
                      lambda: pytest.warns(UserWarning, source2))
        pytest.warns(RuntimeWarning, source3)

    def test_function(self):
        pytest.warns(SyntaxWarning,
                     lambda msg: warnings.warn(msg, SyntaxWarning), "syntax")

    def test_warning_tuple(self):
        pytest.warns((RuntimeWarning, SyntaxWarning),
                     lambda: warnings.warn('w1', RuntimeWarning))
        pytest.warns((RuntimeWarning, SyntaxWarning),
                     lambda: warnings.warn('w2', SyntaxWarning))
        pytest.raises(pytest.fail.Exception,
                      lambda: pytest.warns(
                          (RuntimeWarning, SyntaxWarning),
                          lambda: warnings.warn('w3', UserWarning)))

    def test_as_contextmanager(self):
        with pytest.warns(RuntimeWarning):
            warnings.warn("runtime", RuntimeWarning)

        with pytest.raises(pytest.fail.Exception):
            with pytest.warns(RuntimeWarning):
                warnings.warn("user", UserWarning)

        with pytest.raises(pytest.fail.Exception):
            with pytest.warns(UserWarning):
                warnings.warn("runtime", RuntimeWarning)

        with pytest.warns(UserWarning):
            warnings.warn("user", UserWarning)

    def test_record(self):
        with pytest.warns(UserWarning) as record:
            warnings.warn("user", UserWarning)

        assert len(record) == 1
        assert str(record[0].message) == "user"

    def test_record_only(self):
        with pytest.warns(None) as record:
            warnings.warn("user", UserWarning)
            warnings.warn("runtime", RuntimeWarning)

        assert len(record) == 2
        assert str(record[0].message) == "user"
        assert str(record[1].message) == "runtime"