Assertion Smells.

A test packs many undocumented assertions into one method, so when it fails you can't tell which assertion fired or why — you have to gamble.

An Eager Test verifies several distinct methods or behaviors of the unit under test in a single test method, instead of focusing on one behavior.

A redundant assertion compares a value against itself or against a literal that is equal by construction, so its outcome is fixed and it can never actually fail or detect a regression.

A test method that exercises the code but contains no assertion, so it passes as long as nothing throws — leaving its actual purpose and what it verifies unknown.

A single test method verifies the same condition more than once — repeating an identical assertion or re-checking equivalent logic — instead of removing the redundant check or splitting distinct cases into their own focused tests.

A test verifies behavior by comparing an object's string representation (toString(), JSON.stringify(), rendered HTML) against an expected string literal, coupling the test to incidental formatting rather than the values that actually matter.