1 files changed, 166 insertions, 0 deletions
diff --git a/mako/testing/assertions.py b/mako/testing/assertions.py
new file mode 100644
index 0000000..22221cd
--- /dev/null
+++ b/mako/testing/assertions.py
@@ -0,0 +1,166 @@
+import contextlib
+import re
+import sys
+
+
+def eq_(a, b, msg=None):
+    """Assert a == b, with repr messaging on failure."""
+    assert a == b, msg or "%r != %r" % (a, b)
+
+
+def ne_(a, b, msg=None):
+    """Assert a != b, with repr messaging on failure."""
+    assert a != b, msg or "%r == %r" % (a, b)
+
+
+def in_(a, b, msg=None):
+    """Assert a in b, with repr messaging on failure."""
+    assert a in b, msg or "%r not in %r" % (a, b)
+
+
+def not_in(a, b, msg=None):
+    """Assert a in not b, with repr messaging on failure."""
+    assert a not in b, msg or "%r is in %r" % (a, b)
+
+
+def _assert_proper_exception_context(exception):
+    """assert that any exception we're catching does not have a __context__
+    without a __cause__, and that __suppress_context__ is never set.
+
+    Python 3 will report nested as exceptions as "during the handling of
+    error X, error Y occurred". That's not what we want to do. We want
+    these exceptions in a cause chain.
+
+    """
+
+    if (
+        exception.__context__ is not exception.__cause__
+        and not exception.__suppress_context__
+    ):
+        assert False, (
+            "Exception %r was correctly raised but did not set a cause, "
+            "within context %r as its cause."
+            % (exception, exception.__context__)
+        )
+
+
+def _assert_proper_cause_cls(exception, cause_cls):
+    """assert that any exception we're catching does not have a __context__
+    without a __cause__, and that __suppress_context__ is never set.
+
+    Python 3 will report nested as exceptions as "during the handling of
+    error X, error Y occurred". That's not what we want to do. We want
+    these exceptions in a cause chain.
+
+    """
+    assert isinstance(exception.__cause__, cause_cls), (
+        "Exception %r was correctly raised but has cause %r, which does not "
+        "have the expected cause type %r."
+        % (exception, exception.__cause__, cause_cls)
+    )
+
+
+def assert_raises(except_cls, callable_, *args, **kw):
+    return _assert_raises(except_cls, callable_, args, kw)
+
+
+def assert_raises_with_proper_context(except_cls, callable_, *args, **kw):
+    return _assert_raises(except_cls, callable_, args, kw, check_context=True)
+
+
+def assert_raises_with_given_cause(
+    except_cls, cause_cls, callable_, *args, **kw
+):
+    return _assert_raises(except_cls, callable_, args, kw, cause_cls=cause_cls)
+
+
+def assert_raises_message(except_cls, msg, callable_, *args, **kwargs):
+    return _assert_raises(except_cls, callable_, args, kwargs, msg=msg)
+
+
+def assert_raises_message_with_proper_context(
+    except_cls, msg, callable_, *args, **kwargs
+):
+    return _assert_raises(
+        except_cls, callable_, args, kwargs, msg=msg, check_context=True
+    )
+
+
+def assert_raises_message_with_given_cause(
+    except_cls, msg, cause_cls, callable_, *args, **kwargs
+):
+    return _assert_raises(
+        except_cls, callable_, args, kwargs, msg=msg, cause_cls=cause_cls
+    )
+
+
+def _assert_raises(
+    except_cls,
+    callable_,
+    args,
+    kwargs,
+    msg=None,
+    check_context=False,
+    cause_cls=None,
+):
+    with _expect_raises(except_cls, msg, check_context, cause_cls) as ec:
+        callable_(*args, **kwargs)
+    return ec.error
+
+
+class _ErrorContainer:
+    error = None
+
+
+@contextlib.contextmanager
+def _expect_raises(except_cls, msg=None, check_context=False, cause_cls=None):
+    ec = _ErrorContainer()
+    if check_context:
+        are_we_already_in_a_traceback = sys.exc_info()[0]
+    try:
+        yield ec
+        success = False
+    except except_cls as err:
+        ec.error = err
+        success = True
+        if msg is not None:
+            # I'm often pdbing here, and "err" above isn't
+            # in scope, so assign the string explicitly
+            error_as_string = str(err)
+            assert re.search(msg, error_as_string, re.UNICODE), "%r !~ %s" % (
+                msg,
+                error_as_string,
+            )
+        if cause_cls is not None:
+            _assert_proper_cause_cls(err, cause_cls)
+        if check_context and not are_we_already_in_a_traceback:
+            _assert_proper_exception_context(err)
+        print(str(err).encode("utf-8"))
+
+    # it's generally a good idea to not carry traceback objects outside
+    # of the except: block, but in this case especially we seem to have
+    # hit some bug in either python 3.10.0b2 or greenlet or both which
+    # this seems to fix:
+    # https://github.com/python-greenlet/greenlet/issues/242
+    del ec
+
+    # assert outside the block so it works for AssertionError too !
+    assert success, "Callable did not raise an exception"
+
+
+def expect_raises(except_cls, check_context=False):
+    return _expect_raises(except_cls, check_context=check_context)
+
+
+def expect_raises_message(except_cls, msg, check_context=False):
+    return _expect_raises(except_cls, msg=msg, check_context=check_context)
+
+
+def expect_raises_with_proper_context(except_cls, check_context=True):
+    return _expect_raises(except_cls, check_context=check_context)
+
+
+def expect_raises_message_with_proper_context(
+    except_cls, msg, check_context=True
+):
+    return _expect_raises(except_cls, msg=msg, check_context=check_context)