Unit testing in Docker image in Azure DevOps Pipeline - node.js

Question

I have my PR pipeline with the following stages, one being dependent on the previous one:
Changed: basically determines what services have changed so it ignores testing and buildings ones that haven't.
UnitTesting: installs services into agent pool and runs the unit tests if the services have changes to them.
BuildAndPush: builds and pushes the test-<version> image to ACR if unit tests are passing.
IntegrationTesting: honestly haven't figured this out yet, but it should pull all the images and deploy them somehow.
SeleniumTesting: same as 4.
Anyway, I had UnitTesting before BuildAndPush because I figured it was the quickest way to determine if a build is failing by cutting out the the time of building the image.
It is quicker:
UnitTesting one service takes about 1.5 minutes. The bulk of that is npm install and npm build. The tests themselves are only about 10-15 seconds.
BuildAndPush one service takes about 2.25 minutes, but that doesn't including the testing portion.
That being said I feel like the UnitTesting stage adds an additional 1.25 minutes per service that really isn't necessary: just BuildAndPush and unit test the image would actually be faster overall for the pipeline. The developer would know if the build is failing still well under 5 minutes.
So that is what I can't figure out:
How do you run unit tests in a Docker image in an Azure Pipeline?

Answer 1

How do you run unit tests in a Docker image in an Azure Pipeline?
Since Docker volumes are not supported when building a container. We need to add task to build the image via below script, including running the unit tests, and the copiying the test results file from the container to a folder on the build server. We use the Docker Copy command to do this:
docker build -f ./WebApplication1/Dockerfile --target build -t webapplication1:$(build.buildid) .
docker create -ti --name testcontainer webapplication1:$(build.buildid)
docker cp testcontainer:/src/WebApplication1.UnitTests/TestResults/ $(Build.ArtifactStagingDirectory)/testresults
docker rm -fv testcontainer
When you create a ASP.NET Core project in Visual Studio and add Docker support for it you will get a Docker file that looks something like this:
FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
FROM microsoft/dotnet:2.1-sdk AS build
WORKDIR /src
COPY ["WebApplication1/WebApplication1.csproj", "WebApplication1/"]
RUN dotnet restore "WebApplication1/WebApplication1.csproj"
COPY . .
WORKDIR "/src/WebApplication1"
RUN dotnet build "WebApplication1.csproj" -c Release -o /app
FROM build AS publish
RUN dotnet publish "WebApplication1.csproj" -c Release -o /app
FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "WebApplication1.dll"]
If we want to build and run the tests inside the container, we need to extend the Docker file. For example, add a XUnit test project called WebApplication1.UnitTests.
FROM microsoft/dotnet:2.1-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443
FROM microsoft/dotnet:2.1-sdk AS build
WORKDIR /src
COPY ["WebApplication1/WebApplication1.csproj", "WebApplication1/"]
COPY ["WebApplication1.UnitTests/WebApplication1.UnitTests.csproj", "WebApplication1.UnitTests/"]
RUN dotnet restore "WebApplication1/WebApplication1.csproj"
RUN dotnet restore "WebApplication1.UnitTests/WebApplication1.UnitTests.csproj"
COPY . .
RUN dotnet build "WebApplication1/WebApplication1.csproj" -c Release -o /app
RUN dotnet build "WebApplication1.UnitTests/WebApplication1.UnitTests.csproj" -c Release -o /app
RUN dotnet test "WebApplication1.UnitTests/WebApplication1.UnitTests.csproj" --logger "trx;LogFileName=webapplication1.trx"
FROM build AS publish
RUN dotnet publish "WebApplication1.csproj" -c Release -o /app
FROM base AS final
WORKDIR /app
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "WebApplication1.dll"]
Then add task Publish Test Results to publish the test result.
You could check these blogs for more details:
We start the container with unit tests in Azure DevOps (VSTS)
Running .NET Core Unit Tests with Docker and Azure Pipelines