PR to check if FactorDocs.xml is up-to-date (#48)

* New YML build definition
* Updated documentation

README.md

@@ -120,6 +120,9 @@ Please, refer to our [building guide](BUILDING.md).
 
 We welcome contributions! Please review our [contribution guide](CONTRIBUTING.md).
 
+When submitting pull request with changed or added factor, please make sure you updated factor documentation as described [here](docs/README.md#Documenting-Factors). 
+
+
 ## License
 
 Infer.NET is licensed under the [MIT license](LICENSE.txt).

build/pr-factordocs.yml

@@ -0,0 +1,24 @@
+# Licensed to the .NET Foundation under one or more agreements.
+# The .NET Foundation licenses this file to you under the MIT license.
+# See the LICENSE file in the project root for more information.
+
+# Checks if factordocs.xml is up to date
+
+resources:
+- repo: self
+  clean: true
+  
+trigger: none # disable CI build
+
+steps:
+- task: DotNetCoreInstaller@0
+  inputs:
+    packageType: 'sdk' 
+    version: '2.1.403' 
+
+- script: |
+    echo Checking $(Build.Repository.LocalPath)\src\Runtime\Factors\FactorDocs.xml...
+    dotnet build /p:DisableImplicitNuGetFallbackFolder=true  --configuration ReleaseCore 
+    dotnet run  --configuration ReleaseCore -- "$(Build.Repository.LocalPath)\src\Runtime\Factors\FactorDocs.xml" 
+  displayName: Verify if factordocs.xml is up to date
+  workingDirectory: src/Tools/BuildFactorDoc

docs/README.md

@@ -15,3 +15,19 @@ The last version of the API documentation is in the `apiguide/` folder. If you w
 *   remove temporary folder `InferNet_Copy_Temp`,
 *   switch to gh-pages,
 *   commit and push the new changes.
+
+## Documenting Factors
+
+`Infer.NET` provides tool to automatically generate description text for factor classes, i.e. classes marked with `[FactorMethod]` attribute. Generated descriptions are written to `src/Runtime/Factors/FactorDocs.xml` file and referenced using `<include>` tags in source code triple comments. 
+
+It is important to have full and correct description of all factors, so when you change existing factor or add new one, please follow steps below.
+
+1. Add triple comment
+
+    ```/// <include file='FactorDocs.xml' path='factor_docs/message_op_class[@name="FactorClassName"]/doc/*'/>```
+
+    before newly created factor classes. Replace  `FactorClassName` with actual class name without namespace.
+ 
+2. Run `BuildFactorDoc` project from Microsoft Visual Studio or .NET Core CLI.
+
+3. Commit updated `src/Runtime/Factors/FactorDocs.xml`.