Ensure + validate inventory `record_by_device_id` returns correct result

[davidverweij]

In testing the BTF pipeline, I found the inventory service did not return the appropriate result. Potentially this has to do with the inventory not having an end wear when the device is still being deployed. We should set up some tests to validate this method's functionality, and figure out why it doesn't pick up the query correctly.

Test case

record_by_device_id(
    "BTF-CS4P34",
    start=datetime.datetime(2021, 3, 26, 8, 30, 18, 370009), 
    end=datetime.datetime(2021, 3, 26, 8, 30, 21, 565704))
)

Returns: None

Logs do confirm that when checkin is null, the method does replace it with the current time.

Manually querying the inventory returns:

{
    "data": {
        "K-ABCABC": {
            "patient_id": "K-ABCABC",
            "device_id": "BTF-CS4P34",
            "checkout": "2021-03-18 19:38:49",
            "checkin": null
        },
       "etc" :{
        }
    },
    "meta": {
        "success": true,
        "errors": null
    }
}

Which indicates that is should have returned K-ABCABC. (anonymised)

[jawrainey]

For reference, this is likely becase normalise_day only nulls hours and minutes, and not miliseconds. For example:

>>> now
datetime.datetime(2021, 3, 26, 0, 0, 0, 647241)
>>> endr 
datetime.datetime(2021, 3, 26, 0, 0, 0, 565704)
>>> now <= endr
False

[jawrainey]

This was resolved in #56