[resolver-callback-interface.html]
  [callable resolver]
    expected: FAIL

  [callable resolver: result is not cached]
    expected: FAIL

  [callable resolver: abrupt completion from Call]
    expected: FAIL

  [callable resolver: no 'lookupNamespaceURI' lookups]
    expected: FAIL

  [object resolver]
    expected: FAIL

  [object resolver: this value and `prefix` argument]
    expected: FAIL

  [object resolver: 'lookupNamespaceURI' is not cached]
    expected: FAIL

  [object resolver: abrupt completion from Get]
    expected: FAIL

  [object resolver: 'lookupNamespaceURI' is thruthy and not callable]
    expected: FAIL

  [object resolver: 'lookupNamespaceURI' is falsy and not callable]
    expected: FAIL