Error in spec files when building/testing

[michaelkleinhenz]

An error is appearing when building (without excluding specs in tsconfig) or unit testing:

ERROR in ./src/app/work-item/work-item-list/work-item-list.component.spec.ts
(83,20): error TS2352: Type '{ 'attributes': { 'system.created_at': null; 'system.description': null; 'system.remote_item_id':...' cannot be converted to type 'Wo
rkItem'.
Types of property 'attributes' are incompatible.
Type '{ 'system.created_at': null; 'system.description': null; 'system.remote_item_id': null; 'system.s...' is not comparable to type 'WorkItemAttributes'.
Property ''previousitem'' is missing in type '{ 'system.created_at': null; 'system.description': null; 'system.remote_item_id': null; 'system.s...'.

ERROR in ./src/app/work-item/work-item-list/work-item-detail/work-item-detail.component.spec.ts
(90,20): error TS2352: Type '{ 'attributes': { 'system.created_at': null; 'system.description': null; 'system.remote_item_id':...' cannot be converted to type 'Wo
rkItem'.
Types of property 'attributes' are incompatible.
Type '{ 'system.created_at': null; 'system.description': null; 'system.remote_item_id': null; 'system.s...' is not comparable to type 'WorkItemAttributes'.
Property ''previousitem'' is missing in type '{ 'system.created_at': null; 'system.description': null; 'system.remote_item_id': null; 'system.s...'.