index.js 2.8 KB

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  1. 'use strict';
  2. var test = require('tape');
  3. var forEach = require('for-each');
  4. var v = require('es-value-fixtures');
  5. var isSymbol = require('../index');
  6. var hasSymbols = require('has-symbols')();
  7. var hasToStringTag = require('has-tostringtag/shams')();
  8. var inspect = require('object-inspect');
  9. test('non-symbol values', function (t) {
  10. var nonSymbols = v.nonSymbolPrimitives.concat(
  11. Object(true),
  12. Object(false),
  13. // @ts-expect-error TS sucks with concat
  14. {},
  15. [],
  16. /a/g,
  17. new Date(),
  18. function () {},
  19. NaN
  20. );
  21. t.plan(nonSymbols.length);
  22. forEach(nonSymbols, function (nonSymbol) {
  23. t.equal(isSymbol(nonSymbol), false, inspect(nonSymbol) + ' is not a symbol');
  24. });
  25. t.end();
  26. });
  27. test('faked symbol values', function (t) {
  28. t.test('real symbol valueOf', { skip: !hasSymbols }, function (st) {
  29. var fakeSymbol = { valueOf: function () { return Symbol('foo'); } };
  30. st.equal(isSymbol(fakeSymbol), false, 'object with valueOf returning a symbol is not a symbol');
  31. st.end();
  32. });
  33. t.test('faked @@toStringTag', { skip: !hasToStringTag }, function (st) {
  34. /** @type {{ valueOf(): unknown; [Symbol.toStringTag]?: unknown }} */
  35. var fakeSymbol = { valueOf: function () { return Symbol('foo'); } };
  36. fakeSymbol[Symbol.toStringTag] = 'Symbol';
  37. st.equal(isSymbol(fakeSymbol), false, 'object with fake Symbol @@toStringTag and valueOf returning a symbol is not a symbol');
  38. /** @type {{ valueOf(): unknown; [Symbol.toStringTag]?: unknown }} */
  39. var notSoFakeSymbol = { valueOf: function () { return 42; } };
  40. notSoFakeSymbol[Symbol.toStringTag] = 'Symbol';
  41. st.equal(isSymbol(notSoFakeSymbol), false, 'object with fake Symbol @@toStringTag and valueOf not returning a symbol is not a symbol');
  42. st.end();
  43. });
  44. var fakeSymbolString = { toString: function () { return 'Symbol(foo)'; } };
  45. t.equal(isSymbol(fakeSymbolString), false, 'object with toString returning Symbol(foo) is not a symbol');
  46. t.end();
  47. });
  48. test('Symbol support', { skip: !hasSymbols }, function (t) {
  49. t.test('well-known Symbols', function (st) {
  50. /** @type {(name: string) => name is Exclude<keyof SymbolConstructor, 'for' | 'keyFor'>} */
  51. var isWellKnown = function filterer(name) {
  52. return name !== 'for' && name !== 'keyFor' && !(name in filterer);
  53. };
  54. var wellKnownSymbols = Object.getOwnPropertyNames(Symbol).filter(isWellKnown);
  55. wellKnownSymbols.forEach(function (name) {
  56. // eslint-disable-next-line no-extra-parens
  57. var sym = Symbol[/** @type {keyof SymbolConstructor} */ (name)];
  58. st.equal(isSymbol(sym), true, inspect(sym) + ' is a symbol');
  59. });
  60. st.end();
  61. });
  62. t.test('user-created symbols', function (st) {
  63. var symbols = v.symbols.concat(
  64. Symbol(),
  65. Symbol('foo'),
  66. Symbol['for']('foo'),
  67. Object(Symbol('object'))
  68. );
  69. symbols.forEach(function (sym) {
  70. st.equal(isSymbol(sym), true, inspect(sym) + ' is a symbol');
  71. });
  72. st.end();
  73. });
  74. t.end();
  75. });