Error mock Apollo: «Failed to match 1 mock for this query, which had the following variables:»

Este mock:

const linksMock = {
  request: {
    query: STRUCTURE_STRUCTURE_LINKS_QUERY,
    variables: { id: "60217" },
  },
  result: { data: { dataStructure: dataStructureWithLinks } },
};

provocaba este error:

yarn test StructureStructureLinks

  console.log
    ERROR ApolloError: No more mocked responses for the query: query DataStructureLinks($id: ID!) {
      dataStructure(id: $id) {
        id
        dataStructureLinks {
          labels {
            name
          }
          source {
            id
            currentVersion {
              name
              pathWithIds {
                data_structure_id
                name
              }
            }
            system {
              id
              name
            }
          }
          target {
            id
            external_id
            currentVersion {
              name
              pathWithIds {
                data_structure_id
                name
              }
            }
            system {
              id
              name
            }
          }
        }
        currentVersion {
          id
          name
        }
      }
    }
    
    Expected variables: {"id":60217}
    
    Failed to match 1 mock for this query, which had the following variables:
      {"id":"60217"}

Si nos fijamos en las dos últimas líneas, el error es en las comillas en «60217». Al quitarlas ya funciona:

const linksMock = {
  request: {
    query: STRUCTURE_STRUCTURE_LINKS_QUERY,
    variables: { id: 60217 },
  },
  result: { data: { dataStructure: dataStructureWithLinks } },
};