1. groups Attribute
   1. A way to add any number of test methods to a named list.
   2. Opportunity to run only those lists of test methods according to their group name.
   3. Group names can consist of a module of our application, a certain test type.
   4. Plus, one test method can be a part of more than one group. For example, you can add sign in the test method to a group for smoke tests, and to another group for regression tests. A class can also be added to a group.
2. dependsOnGroups Attribute
   1. It is similar to dependsOnMethods attribute in that it allows us to define a group name that our test method depends on.
   2. Every method member of a group is guaranteed to be invoked before a method that depends on this group.
3. Execute Groups via XML File
   1. <groups> tag : Allows two tags: <run> & <define>.
   2. <run> tag : Lists groups that can be included or excluded.
   3. <define> tag : Helps us create a new group based on existing groups.
4. Run Test Methods According To Group Name
   1. a <run> that has no <include> & no <exclude> will run all test methods
   2. if we include a group then only test methods assigned to that group will run
   3. if we include more than one group then members of all included groups will be run
   4. excluding a group runs all test methods except test methods assigned to that group
   5. we can use regular expressions to specify group names that should be included or excluded
   6. if a test method belongs to a group that is included but also belongs to another group that is excluded, then the test will not run because excluded wins