Directory.Build.targets

<?xml version="1.0" encoding="utf-8"?>
<Project>

  <!-- This target is used to compute the inputs and outputs for incrementally running the Yarn up to date check.-->
  <Target
    Name="EnsureJavaScriptCodeUpToDateInputAndOutputs"
    >
    <ItemGroup>
      <_EnsureJavaScriptCodeUpToDateInputFiles Include="$(MSBuildThisFileDirectory)yarn.lock" />
      <_EnsureJavaScriptCodeUpToDateInputFiles Include="$(MSBuildThisFileDirectory)\**\package.json" Exclude="$(MSBuildThisFileDirectory)\node_modules\**" />
      <_EnsureJavaScriptCodeUpToDateOutputFiles Include="@(_EnsureJavaScriptCodeUpToDateInputFiles->'$(RootIntDir)\JsUpToDateCheck\%(RecursiveDir)%(Filename)%(Extension).dummy')" />
    </ItemGroup>
  </Target>

  <!-- This target checks if Yarn install needs to run or not. This is a common cause of failed builds for developers not used to running it after syncing... -->
  <Target
    Name="EnsureJavaScriptCodeUpToDate"
    BeforeTargets="BeforeBuild"
    DependsOnTargets="EnsureJavaScriptCodeUpToDateInputAndOutputs"
    Inputs="@(_EnsureJavaScriptCodeUpToDateInputFiles)"
    Outputs="@(_EnsureJavaScriptCodeUpToDateOutputFiles)"
    >

    <Message Text="Checking if yarn is 'up to date' by running a 'dry-run' version of `yarn install` and checking the exit code" />
    <Exec 
      ContinueOnError="True"
      Command="npx yarn install --offline --cache-folder $(RootIntDir)\JsUpToDateCheck\Cache"
      WorkingDirectory="$(MSBuildThisFileDirectory)"
      >
      <Output TaskParameter="ExitCode" ItemName="_YarnExitCode"/>
    </Exec>

    <!-- Fail the build if yarn needs to install packages. -->
    <Error 
      Condition="'%(_YarnExitCode.Identity)' != '0'"
      Text="Yarn packages are out of date. Please run `yarn install &amp;&amp; yarn build` in the root of the repo to ensure the generated files are up to date" 
    />

    <!-- 
      Copy the yarn.lock file to prevent this task from running over and over again, and only rerun the check with yarn.lock or any package.json changes. 
      This will likely miss a few corner cases with local changes to package.json but should catch the most important case after syncing
    -->
    <Copy
      Condition="'%(_YarnExitCode.Identity)' == '0'"
      SourceFiles="@(_EnsureJavaScriptCodeUpToDateInputFiles)"
      DestinationFiles="@(_EnsureJavaScriptCodeUpToDateOutputFiles)"
      SkipUnchangedFiles="true" />
    <!-- We have to touch the outputs to ensure up to date incrementaility works-->
    <Touch Files="@(_EnsureJavaScriptCodeUpToDateOutputFiles)" />

  </Target>


</Project>