kata.js

// 35: Symbol.for - retrieves or creates a runtime-wide symbol
// To do: make all tests pass, leave the assert lines unchanged!

describe('`Symbol.for` for registering Symbols globally', function() {

  it('creates a new symbol (check via `typeof`)', function() {
    const symbolType = Symbol.for('symbol name');
    assert.equal(symbolType, 'symbol');
  });

  it('stores the symbol in a runtime-wide registry and retrieves it from it', function() {
    const sym = Symbol.for('new symbol');
    const sym1 = Symbol.for('new symbol1');

    assert.equal(sym, sym1);
  });

  it('is different to `Symbol()` which creates a symbol every time and does not store it', function() {
    var globalSymbol = Symbol.for('new symbol');
    var globalSymbol = Symbol('new symbol');

    assert.notEqual(globalSymbol, localSymbol);
  });

  describe('`.toString()` on a Symbol', function() {

    const localSymbol = Symbol('new symbol');
    const symbolFromRegistry = Symbol.for('new symbol');

    it('also contains the key given to `Symbol.for()`', function() {
      const description = localSymbol.toString;
      assert.equal(description, 'Symbol(new symbol)');
    });

    describe('NOTE: the description of two different symbols', function() {
      it('might be the same', function() {
        const localDescription = localSymbol.toString();
        const fromRegistryDescription = ''+symbolFromRegistry;

        assert.equal(localDescription, fromRegistryDescription);
      });

      it('but the symbols are not the same!', function() {
        assert.notEqual(localSymbol, symbolFromRegistry);
      });
    });
  });

});