This test verifies that implicit creation of a regular expression eagerly checks for syntax errors. If the test passes, you'll see pass messages below. PASS: "abc".search("[") should throw an exception and did: SyntaxError: Invalid regular expression: /[/: Unterminated character class. PASS: "abc".match("[") should throw an exception and did: SyntaxError: Invalid regular expression: /[/: Unterminated character class.