Where are unit tests stored?
Unit tests are implemented as stored procedures in the database that is being tested. All tests in database must have prefix test in the test name:

Does ApexSQL Unit Test integrate with SSMS?
Yes, ApexSQL Unit Test integrates with SSMS 2012 and later.
What is tSQLt?
tSQLt is a database unit testing framework for Microsoft SQL Server. It is a pre-requisite for using ApexSQL Unit Test since provides the ability to mock out tables and tSQLt
What value does ApexSQL Unit Test offer on top of tSQLt?
ApexSQL Unit Test utilizes the tSQLt framework and provides a UI in SSMS to make it easier to manage your unit tests. It also provides a set of static analysis tests, also known as SQL Cop tests, to help detect issues with your database, and it shows result of tests (total number of tests, number of executed, passed and failed tests).
Are there sample tests to get started with?
Yes, ApexSQL Unit Test offers set of database unit tests using SQL Cop and a sample database with some predefined tests.
What systems/environments are supported?
ApexSQL Unit Test supports SQL Server 2005, SSMS 2012, Windows Server 2008/Windows Vista, to their latest versions, .NET 4.5 framework must be installed.
Is there a possibility to re-install tsqlt from web if it is already installed from PC?
Yes, if the tSQLt is already installed on same database it can be reinstalled from a different source following next steps:
Select a database and right click on it:

When you click on Reinstall\Update option you will get following window to choose installation source:

How does ApexSQL Unit Test execute tests?
ApexSQL Unit Test execute tests as stored procedures. Possible results are “Fail” and” Pass”.
How do I see the list of tests that are already in the database?
In the Unit Test explorer all tests will be visible for selected database:

How can I run all test from server or database?
All tests on a particular server can be run by clicking on the button “Run selected” from the context menu

Can ApexSQL Unit Test be automated?
Yes, ApexSQL Unit Test can be automated using the CLI.