Testing PR instructions (#2113)

* Testing PR instructions

* Fix typo

README.md

@@ -31,6 +31,8 @@ Older versions and unstable nightly build are also available at <https://github.
 
 For instructions on how to build stylesheets, please [see here](./doc/how_to_stylesheet.md).
 
+Can't develop but still want to help? Help us test individual Pull Requests before they are merged with [these steps](./doc/how_to_test_prs.md).
+
 ## Community
 
 - To share tips or to troubleshoot, join the [Google OpenToonz Users forum](https://groups.google.com/forum/#!forum/opentoonz_en)

doc/how_to_test_prs.md

@@ -0,0 +1,47 @@
+# Testing Pull Requests (PRs)
+
+When a PR is submitted, it is compiled automatically by AppVeyor and Travis CI. The AppVeyor build creates an artifact which contains the OpenToonz executable and supporting DLLs needed to run.  You can easily download this artifact and run it to test out the PR before it is merged.
+
+## Pre-Testing Notes
+- This can only be tested on Windows. There is no OSX or Linux build that can be tested.
+- You need to have OpenToonz already installed.  Do not uninstall.
+- Your current personal preferences and settings will be used.
+  - Personal settings can change if you change them while testing.
+  - It is recommended that you backup your `C:\OpenToonz #.# stuff` folder before testing a PR.
+- The AppVeyor build does not contain an updated `C:\OpenToonz #.# stuff` folder so any PR changes to default configurations (i.e. stylesheets, FXs, brushes, etc) are not automatically included.
+- It is recommended when testing to use new scenes that you can throw away.
+  - If you decide to test on an existing scene, back it up first!
+
+## Downloading and Testing AppVeyor Builds
+
+- Go to the PR you are interested in checking out.
+
+- Scroll to the bottom of the page and look for the green-outlined box with `All checks have passed` in it. Click on `Show all checks` next to it.
+
+![](./testing_pr_1.JPG)
+
+- Look for where it says `AppVeyor build succeeded` and click on the `Details` next to it.
+
+![](./testing_pr_2.JPG)
+
+- Click on `Configuration: Release`.
+
+![](./testing_pr_3.JPG)
+
+- On the right side of the page, click on `Artifacts`.
+
+![](./testing_pr_4.JPG)
+
+- Click on the OpenToonz `.zip` file to begin the download.
+
+![](./testing_pr_5.JPG)
+
+- Once download is complete, go to your Downloads folder and extract the contents of the .zip file anywhere on your computer.
+ - You should extract into a separate folder. 
+ - ⚠️ **Do not overwrite your current OpenToonz installation!**
+
+- Enter the folder you extracted everything into and double-click the OpenToonz executable to start.
+
+- Test away!  Report any suggestions or issues related to the change in the PR comments.
+
+- You can safely delete the .zip file and the folder you created when you are done.