Unit testing in Docker image in Azure DevOps Pipeline

Question

I have my PR pipeline with the following stages, one being dependent on the previous one:

1. Changed: basically determines what services have changed so it ignores testing and buildings ones that haven't.
2. UnitTesting: installs services into agent pool and runs the unit tests if the services have changes to them.
3. BuildAndPush: builds and pushes the test-<version> image to ACR if unit tests are passing.
4. IntegrationTesting: honestly haven't figured this out yet, but it should pull all the images and deploy them somehow.
5. 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