Update contributing doc to to include testing information (#4222)

* Update to include testing information

* Update

CONTRIBUTING.md

@@ -1,24 +1,71 @@
 ## Running the latest runtime version
-### Dependencies
+
+## Dependencies
 
 There is a dependency on the .NET Core tools for the cross platform support. You can [install these here](https://www.microsoft.com/net/core).
 
 To install the required dotnet packages navigate into the repository root and run `dotnet restore`
 
-### Compiling the CLI Tools
+## Compiling the CLI Tools
+
 To build the project run `cd src/Azure.Functions.Cli; dotnet build` (note navigating into the src directory is required due to the test suite currently failing to compile on non-windows environments - see below)
 
 ### Running against a function app
+
 To test this project against a local function app you can run from that function app's directory
 
 `dotnet run --project PATH_TO_FUNCTIONS_CLI/src/Azure.Functions.Cli start`
 
 where PATH_TO_FUNCTIONS_CLI is the absolute or relative path to the root of this repository.
 
-## Running the Test Suite
-You cannot run the test suite at this moment in time using DotNet Core. We will update this file when this becomes possible.
+### Running the Test Suite
+
+- Build the solution `dotnet build Azure.Functions.Cli.sln`
+  - As part of this build, the cli is copied into the test project's output directory (`test/Azure.Functions.Cli.Tests/bin/Debug/net8.0`) - this is what will be used by the tests
+  - If you wish to override this, you can set the `FUNC_PATH` environment variable to the path of the `func`/`func.exe` you wish to test against
+- Run the test suite in Visual Studio Test Explorer or by running `dotnet test` from the `test` project root.
+  - i.e. `cd test/Azure.Functions.Cli.Tests; dotnet test`
+
+#### Storage Emulator
+
+Some tests, namely E2E, require an Azure storage emulator to be running. You can download the storage emulator [here](https://learn.microsoft.com/en-us/azure/storage/common/storage-use-azurite?tabs=visual-studio%2Cblob-storage).
+
+Run the emulator before your run the tests.
+
+> There is a script you can use for this as well, see `tools/start-emulators.ps1`
+
+#### Templates missing
+
+If you see an error saying the templates folder is missing, you can follow either of the following steps:
+
+##### (a)
+
+- Find your offical func instation directory
+  - i.e. `/opt/homebrew/Cellar/azure-functions-core-tools@4/4.0.6610`
+  - or `%LOCALAPPDATA%\AzureFunctionsTools\Releases\4.69.0\cli_x64\`
+- Copy the templates folder to the test project's output directory (`test/Azure.Functions.Cli.Tests/bin/Debug/net8.0`)
+
+##### or (b)
+
+- Update `build/Program.cs` to just add the template nugets and json:
+
+    ```csharp
+    Orchestrator
+        .CreateForTarget(args)
+        .Then(AddTemplatesNupkgs)
+        .Then(AddTemplatesJson)
+        .Run();
+    ```
+- Set environment variables required to run the build script
+  - Windows: `$env:IsReleaseBuild = "false"`
+  - MacOS: `export IsReleaseBuild=false`
+    - If using M1/M2, you may need to set the dotnet root as well `export DOTNET_ROOT=/usr/local/share/dotnet/x64`
+- Run the build script `build.ps1`
+- In the `artifacts` folder, you should find a `templates` folder within any the subfolders here
+- Copy the `templates` folder to the test project's output directory (`test/Azure.Functions.Cli.Tests/bin/Debug/net8.0`)
 
 ## Contributing to this Repository
+
 ### Filing Issues
 
 Filing issues is a great way to contribute to the SDK. Here are some guidelines:
@@ -27,8 +74,8 @@ Filing issues is a great way to contribute to the SDK. Here are some guidelines:
 * Point to a test repository (e.g. hosted on GitHub) that can help reproduce the issue. This works better then trying to describe step by step how to create a repro scenario.
 * Github supports markdown, so when filing bugs make sure you check the formatting before clicking submit.
 
-
 ### Submitting Pull Requests
+
 If you don't know what a pull request is read this https://help.github.com/articles/using-pull-requests.
 
 Before we can accept your pull-request you'll need to sign a [Contribution License Agreement (CLA)](http://en.wikipedia.org/wiki/Contributor_License_Agreement). You can sign ours [here](https://cla2.dotnetfoundation.org). However, you don't have to do this up-front. You can simply clone, fork, and submit your pull-request as usual.