How to extract coverage report in multistage build?

I want to extract the coverage report while building a docker image in a multistage build. Before I was executing the tests via image.inside using the Jenkins Docker plugin but now I am executing the tests using the following command where I could not extract the coverage report.

docker build -t myapp:test --cache-from registry/myapp:test --target test --build-arg BUILDKIT_INLINE_CACHE=1 .

Is there any way to mount the Jenkins workspace like the below function is doing without running the docker image? There is a --output flag but I could not understand how can I use this if it works. Or can it be possible via RUN --mount=type ...

  image.inside('-u root -v $WORKSPACE/coverage:/var/app/coverage') {
      stage("Running Tests") {
        timeout(10) {
          withEnv(["NODE_ENV=production"]) {
            sh(script: "cd /var/app; yarn run test:ci")
        }

Dockerfile

FROM node:16.15.0-alpine3.15 as base
WORKDIR /var/app
RUN --mount=type=cache,target=/var/cache/apk \
    apk add --update --virtual build-dependencies build-base \
    curl \
    python3 \
    make \
    g++ \
    bash 
COPY package*.json ./
COPY yarn.lock ./
COPY .solidarity ./
RUN --mount=type=cache,target=/root/.yarn YARN_CACHE_FOLDER=/root/.yarn && \
    yarn install --no-progress --frozen-lockfile --check-files && \
    yarn cache clean
COPY . .

FROM base as test
ENV NODE_ENV=production
RUN ["yarn", "run", "format:ci"]
RUN ["yarn", "run", "lint:ci"]
RUN ["yarn", "run", "test:ci"]

FROM base as builder
RUN yarn build

FROM node:16.15.0-alpine3.15 as production
WORKDIR /var/app
COPY  --from=builder /var/app /var/app
CMD ["yarn", "start:envconsul"]

You can make a stage with the output you want to extract:

FROM node:16.15.0-alpine3.15 as base
WORKDIR /var/app
RUN --mount=type=cache,target=/var/cache/apk \
    apk add --update --virtual build-dependencies build-base \
    curl \
    python3 \
    make \
    g++ \
    bash 
COPY package*.json ./
COPY yarn.lock ./
COPY .solidarity ./
RUN --mount=type=cache,target=/root/.yarn YARN_CACHE_FOLDER=/root/.yarn && \
    yarn install --no-progress --frozen-lockfile --check-files && \
    yarn cache clean
COPY . .

FROM base as test
ENV NODE_ENV=production
RUN ["yarn", "run", "format:ci"]
RUN ["yarn", "run", "lint:ci"]
RUN ["yarn", "run", "test:ci"]

FROM scratch as test-out
COPY --from=test /var/app/coverage/ /

FROM base as builder
RUN yarn build

FROM node:16.15.0-alpine3.15 as production
WORKDIR /var/app
COPY  --from=builder /var/app /var/app
CMD ["yarn", "start:envconsul"]

Then you can build with:

docker build \
  --output "type=local,dest=${WORKSPACE}/coverage" \
  --target test-out .