Low memory tests

[SamTov]

• Add tests for all calculators at 1 MB memory limit
• Added helper method to automatically compute memory fraction based on currently available machine memory
• Fixed failing tests in low memory limit

[PythonFZ]

I agree with @PythonFZ that the tests should not be duplicated. Context managers are nice (albeit a bit complicated), something like

def test_stuff():
    do_actual_test()
    mds.set_memory(1mb)
    do_actual_test()

probably also does the trick

The reason for the context manager was, that with mds.set_memory(1mb) we change a global MDSuite setting, so even if the test fails we need to make sure that we revert that change. I don't know if we can be certain that this happens if we don't use a context manager. This would not affect the CI, because here all tests have to pass but for local testing it might cause unexpected behaviour when running tests with pytest -n auto and such a test fails.

[SamTov]

I agree with @PythonFZ that the tests should not be duplicated. Context managers are nice (albeit a bit complicated), something like

def test_stuff():
    do_actual_test()
    mds.set_memory(1mb)
    do_actual_test()

probably also does the trick

The reason for the context manager was, that with mds.set_memory(1mb) we change a global MDSuite setting, so even if the test fails we need to make sure that we revert that change. I don't know if we can be certain that this happens if we don't use a context manager. This would not affect the CI, because here all tests have to pass but for local testing it might cause unexpected behaviour when running tests with pytest -n auto and such a test fails.

I like the idea but if you could write them or at least some it would be helpful as I am not sure of the best way to do it. Also, if you do that, see if you can replicate the CI error locally. It says that time isn't in the data that is loaded but this is not true...

[SamTov]

@PythonFZ Thanks for moving all the calculators that's awesome. Looks a lot nicer now. I realise the issue is that the data is loaded and then popped once and then we try it again. I will fix it now.