Order of Events - MSBuild and Task Runner Bindings (Gulp) - msbuild

Question

I am using a TFS build project to build a Visual Studio 2015 project that contains a gulpfile for compiling SASS among other things. I am trying to understand the sequence of events using MSBuild Tasks and Task Runner bindings. It appears that MSBuild knows enough to detect and run my default gulp task BeforeBuild:
/// <binding BeforeBuild='default' />
var gulp = require('gulp');
var sass = require('gulp-sass');
var importer = require('sass-importer-npm');
gulp.task('sass', function () {
return gulp.src([
'./sass/**/*.scss',
'./node_modules/font-awesome/scss/**/*.scss'
])
.pipe(sass({ importer: importer }).on('error', sass.logError))
.pipe(gulp.dest('./Content/css'));
});
I am to using an MSBuild target to run after the BeforeBuild target so that I can include the generated files in the project for publishing:
<Target Name="CopyGulpFiles" AfterTargets="BeforeBuild">
Here is my MSBuild call in my build .proj file with the relevant info:
<ItemGroup>
<ProjectsToBuild Include="$(MSBuildThisFileDirectory)..\MyProject.sln">
<AdditionalProperties>
VisualStudioVersion=$(VisualStudioVersion);
OutputPath=$(OutputRoot);
WebPublishMethod=FileSystem;
publishUrl=$(StageFolder);
DeployOnBuild=false;
DeployTarget=WebPublish;
PublishProfile=$(MSBuildThisFileFullPath)
</AdditionalProperties>
</ProjectsToBuild>
</ItemGroup>
<MSBuild Projects="#(ProjectsToBuild)" Properties="Configuration=Dev"/>
These two things seem to run in the right order everytime I run them. This raises some questions though:
Would the 'BeforeBuild' binding for Task Runner get executed before the 'BeforeBuild' target in MSBuild?
Are the order of bindings/targets deterministic here?
Does using the AfterTargets property ensure that this is run after the whole 'BeforeBuild' stage (targets and bindings) are completed?
How does MSBuild know how to use my Gulp file? I assume it has to be the same mechanism as visual studio uses.

Answer 1

I ran into the issue where everything worked locally when building with the Task Runner, but Gulp was never called by MSBuild.
I ended up with the following solution, which extends the Compile task with our custom target GulpBuild. In this snippet build is the name of my Gulp task.
<PropertyGroup>
<CompileDependsOn>
$(CompileDependsOn);
GulpBuild;
</CompileDependsOn>
</PropertyGroup>
<Target Name="GulpBuild">
<Exec Command="npm install" />
<Exec Command="gulp build" />
</Target>
Steve Cadwallader's post was very helpful in solving this issue.
The BeforeBuild target should always run before BeforeBuild in MSBuild. The Task Runner is specific to Visual Studio, so this will only happen when building in Visual Studio.
This will help with your questions about ordering.