Initial Fork from https://bitbucket.org/raphaelmutschler/calibreserver/

lib/sqlalchemy/testing/warnings.py

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+from __future__ import absolute_import
+
+import warnings
+from .. import exc as sa_exc
+from .. import util
+
+
+def testing_warn(msg, stacklevel=3):
+    """Replaces sqlalchemy.util.warn during tests."""
+
+    filename = "sqlalchemy.testing.warnings"
+    lineno = 1
+    if isinstance(msg, basestring):
+        warnings.warn_explicit(msg, sa_exc.SAWarning, filename, lineno)
+    else:
+        warnings.warn_explicit(msg, filename, lineno)
+
+
+def resetwarnings():
+    """Reset warning behavior to testing defaults."""
+
+    util.warn = util.langhelpers.warn = testing_warn
+
+    warnings.filterwarnings('ignore',
+                            category=sa_exc.SAPendingDeprecationWarning)
+    warnings.filterwarnings('error', category=sa_exc.SADeprecationWarning)
+    warnings.filterwarnings('error', category=sa_exc.SAWarning)
+
+
+def assert_warnings(fn, warnings):
+    """Assert that each of the given warnings are emitted by fn."""
+
+    from .assertions import eq_, emits_warning
+
+    canary = []
+    orig_warn = util.warn
+
+    def capture_warnings(*args, **kw):
+        orig_warn(*args, **kw)
+        popwarn = warnings.pop(0)
+        canary.append(popwarn)
+        eq_(args[0], popwarn)
+    util.warn = util.langhelpers.warn = capture_warnings
+
+    result = emits_warning()(fn)()
+    assert canary, "No warning was emitted"
+    return result