update test docs

Author: lowlydba

tests/README.md

@@ -1,11 +1,40 @@
 # Tests
 
-Unit tests via [tSQLt](https://tsqlt.org/) and Pester,
+Unit tests via [tSQLt](https://tsqlt.org/) and Pester run on Appveyor,
 code coverage by
 [SQLCover](https://github.com/GoEddie/SQLCover) and
 [codecov.io](https://codecov.io/), and
 linting by [TSQLLint](https://github.com/tsqllint/tsqllint)
-and [super-linter](https://github.com/github/super-linter)
+and [super-linter](https://github.com/github/super-linter).
+
+## How it works
+
+### tSQLt unit tests
+
+Each stored procedure has all of its tSQLt unit tests stored in a single sql script in the `\tests\` folder and
+uses the naming convention of `sp_name.Tests.sql`. These should mostly adhere to the following naming conventions:
+
+- `[sp_name].[test sp fails ...]`
+- `[sp_name].[test sp succeeds ...]`
+
+### Pester tests
+
+All of a stored proc's unit tests are run by a single corresponding Pester script, similarly
+named `sp_name.Tests.ps1`, which:
+
+- Installs the DBA MultiTool scripts
+- Installs the corresponding stored procedure's tSQLt tests
+- Runs all unit tests for the stored procedure as a single Pester invocation
+
+This avoids having to hard-code or do messy querying to get each individual Pester test for a stored procedure
+at the expense of obfuscating more detailed output (i.e. one failed test among 20 counts as a full falure in Appveyor). 
+
+The output is printed in each [Appveyor](https://ci.appveyor.com/project/LowlyDBA/dba-multitool) job if a failure needs to be inspected.
+
+### Appveyor
+
+Each Pester test is then run against each configuration defined in `\appveyor\appveyor.yml` in order
+to test against all supported SQL Server versions. These are auto-triggered for each commit made in a pull request.
 
 ## How to run
 
@@ -14,22 +43,18 @@ and [super-linter](https://github.com/github/super-linter)
 The following prereqs are *not* handled by the setup script:
 
 * SQL Server 2012+ or equivalent
-* tSQLt installed on a database (install scripts located in `tests\tSQLt\` if needed)
+* tSQLt installed on a database (run `appveyor\install_tsqlt.ps1` manually)
 
 ### Steps
 
 1. Temporarily update `tests\constants.ps1` with any values
 specific to your local environment (Instance and Database)
 
-2. Run the following PowerShell from the project root:
-
-```powershell
-.\tests\localdev_test.ps1
-```
+2. Run the following PowerShell from the project root `tests\localdev_test.ps1`
 
 This will:
 
 * Install all dependencies (except a tSQLt database)
 * Produce an html code coverage report on completion in a popup browser
 
-To skip the automated setup, use the flag `-SkipSetup` when running the script.
+To skip the automated setup of dependencies, use the flag `-SkipSetup` when running the script.