Unexpected behavior for Quantity without a code

[brynrhodes]

In the following library:

library TestQuantity

using FHIR version '4.0.1'

include FHIRHelpers version '4.0.1'

context Patient

define TestQuantity: FHIRHelpers.ToValue(FHIR.Quantity { value: FHIR.decimal { value: 1001 }, unit: FHIR.string { value: 'mg/dL' } }) >= 200 'mg/dL'

The TestQuantity expression unexpectedly returns null, when according to the logic in the FHIRHelpers library, the unit element should be treated as a UCUM unit unless there is explicit declaration that it is not.

[brynrhodes]

Note that this is somewhat related to this issue:

#961

The proposed fix is to ensure that when casting Quantity values to Quantity-sub-type values, all the elements of the Quantity are considered (as opposed to just the value and code, which is what it currently does).

This is an improvement on, but still not a complete fix for issue 961. The full fix is documented as TODOs in the FHIRModelResolver classes.