<Li> Having test cases depend on system state manipulated from previously executed test cases (i.e., you should always start a unit test from a known and pre-configured state). </Li> <Li> Dependencies between test cases . A test suite where test cases are dependent upon each other is brittle and complex . Execution order should not be presumed . Basic refactoring of the initial test cases or structure of the UUT causes a spiral of increasingly pervasive impacts in associated tests . </Li> <Li> Interdependent tests . Interdependent tests can cause cascading false negatives . A failure in an early test case breaks a later test case even if no actual fault exists in the UUT, increasing defect analysis and debug efforts . </Li> <Li> Testing precise execution behavior timing or performance . </Li>

When will you start writing the unit test