sage.tensor.modules.free_module_basis: Add testsuite

[Matthias Köppe]

We add a _test... method to Basis_abstract and run the test suite for some instances of FreeModuleBasis, FreeModuleCoBasis.

[Matthias Köppe]

The tests currently fail:

File "src/sage/tensor/modules/free_module_basis.py", line 388, in sage.tensor.modules.free_module_basis.FreeModuleCoBasis
Failed example:
    TestSuite(f).run()
...
    IndexError: index out of range: 0 not in [1, 3]
    ------------------------------------------------------------
    The following tests failed: _test_iter_len

File "src/sage/tensor/modules/free_module_basis.py", line 400, in sage.tensor.modules.free_module_basis.FreeModuleCoBasis.?
Failed example:
    TestSuite(f).run()
...
      File "/Users/mkoeppe/s/sage/sage-rebasing/worktree-algebraic-2018-spring/local/lib/python3.7/site-packages/sage/tensor/modules/free_module_basis.py", line 98, in _test_iter_len
        tester.assertTrue(x in self.free_module())
      File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/case.py", line 705, in assertTrue
        raise self.failureException(msg)
    AssertionError: False is not true
    ------------------------------------------------------------
    The following tests failed: _test_iter_len

---

New commits:

​1e69c0e

sage.tensor.modules.free_module_basis.Basis_abstract: Add _test_iter_len

[Matthias Köppe]

Should the method FreeModuleCoBasis.free_module really return the (primal) base module, as it currently does? Or rather the dual of it?

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​f1f67d3

FreeModuleCoBasis: Add _test_iter_len

[Travis Scrimshaw]

While there is a bit of ambiguity, considering the output:

sage: f
Dual basis (e^0,e^1,e^2) on the Rank-3 free module M over the Integer Ring

which is saying that it is a dual basis of M, I think it is fair that free_module returns the base module rather than its dual. As such, I am setting this to a positive review.

[Matthias Köppe]

Thanks!