Tests on metamodel services => DONE, Tests on metamodel selectors => WIP

client/src/app/metamodel/selectors/select.selector.spec.ts

...app/metamodel/services/attribute-distinct.service.spec.ts

.../src/app/metamodel/services/attribute-distinct.service.ts

client/src/app/metamodel/services/attribute.service.spec.ts

client/src/app/metamodel/services/attribute.service.ts

client/src/app/metamodel/services/column.service.spec.ts

client/src/app/metamodel/services/column.service.ts

...rc/app/metamodel/services/criteria-family.service.spec.ts

client/src/app/metamodel/services/criteria-family.service.ts

client/src/app/metamodel/services/database.service.spec.ts

client/src/app/metamodel/services/database.service.ts

...src/app/metamodel/services/dataset-family.service.spec.ts

client/src/app/metamodel/services/dataset-family.service.ts

client/src/app/metamodel/services/dataset.service.spec.ts

client/src/app/metamodel/services/dataset.service.ts

client/src/app/metamodel/services/group.service.spec.ts

client/src/app/metamodel/services/group.service.ts

client/src/app/metamodel/services/survey.service.spec.ts

client/src/test-data.ts