This page covers some common testing best practices and anti-patterns
Best Practices
Be Test-Driven
Come up with a list of end to end, component/service and unit tests that will be needed to show that the user story, requirement or improvement work as expected. Write the first the first test(s), run them to see them fail, provide an implementation, run the test(s), refactor and/or fix any problems, rinse and repeat.
Write BDD-Style Tests
Test behavior, not logic. , not Write your tests following the BDD style