TST, MAINT: Lots of new tests for fromnumeric.py - #7027

Please don't rebase.

PR is no longer WIP. Travis + Appveyor are both passing. Should be good to merge now.

Looks generally good, but the common mistake is to substitute methods for functions. The two aren't the same despite the apparent redundancy. The methods should actually be tested in the numpy/core/tests/test_multiarray.py huge TestMethods class. Note that Numeric was the first version of what became Numpy and didn't have many methods.

@charris : Changes made and Travis / Appveyor are happy.

I think you need to check carefully where functions/methods etc are defined. The easy way to check functions in ipython is to use the ? help option on the function name. Or you can look at the __all__ list in the modules to see what functions are exported. You can check ndarray methods with ndarray.<themethod>?.

If you look at the functions defined in fromnumeric.py, almost all of them are tested elsewhere in the code-base, even though they are in the __all__ array. For example np.prod is defined here, but the test is here.

My original intention was to write an entire test_fromnumeric.py but after searching the code base for many of these functions, I realized that I would just be duplicating already existing tests.

Thanks @gfyoung .