[3.5] bpo-29403: Fix mock's broken autospec behavior on method-bound builtin functions (GH-3) #2809
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…builtin functions (pythonGH-3) Cython will, in the right circumstances, offer a MethodType instance where im_func is a builtin function. Any instance of MethodType is automatically assumed to be a Python-defined function (more specifically, a function that has an inspectable signature), but _set_signature was still conservative in its assumptions. As a result _set_signature would return early with None instead of a mock since the im_func had no inspectable signature. This causes problems deeper inside mock, as _set_signature is assumed to _always_ return a mock, and nothing checked its return value. In similar corner cases, autospec will simply not check the spec of the function, so _set_signature is amended to now return early with the original, not-wrapped mock object. Patch by Aaron Gallagher. (cherry picked from commit 856cbcc)
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Cython will, in the right circumstances, offer a MethodType instance
where im_func is a builtin function. Any instance of MethodType is
automatically assumed to be a Python-defined function (more
specifically, a function that has an inspectable signature), but
_set_signature was still conservative in its assumptions. As a result
_set_signature would return early with None instead of a mock since
the im_func had no inspectable signature. This causes problems
deeper inside mock, as _set_signature is assumed to always
return a mock, and nothing checked its return value.
In similar corner cases, autospec will simply not check the spec of the
function, so _set_signature is amended to now return early with the
original, not-wrapped mock object.
Patch by Aaron Gallagher.
(cherry picked from commit 856cbcc)
https://bugs.python.org/issue29403