Speed-up CI by reorganizing tests (#22247)

* unit tests: mark slow tests as "maybeslow"

This commit also removes the "network" marker and
marks every "network" test as "maybeslow". Tests
marked as db are maintained, but they're not slow
anymore.

* GA: require style tests to pass before running unit-tests

* GA: make MacOS unit tests fail fast

* GA: move all unit tests into the same workflow, run style tests as a prerequisite

All the unit tests have been moved into the same workflow so that a single
run of the dorny/paths-filter action can be used to ask for coverage based
on the files that have been changed in a PR. The basic idea is that for PRs
that introduce only changes to packages coverage is not necessary, this
resulting in a faster execution of the tests.

Also, for package only PRs slow unit tests are skipped.

Finally, MacOS and linux unit tests are now conditional on style tests passing
meaning that e.g. we won't waste a MacOS worker if we know that the PR has
flake8 issues.

* Addressed review comments

* Skipping slow tests on MacOS for package only recipes

* QA: make tests on changes correct before merging

14 files changed, 367 insertions, 300 deletions

diff --git a/.github/workflows/linux_unit_tests.yaml b/.github/workflows/linux_unit_tests.yaml
deleted file mode 100644
index a5fdd7b345..0000000000
--- a/.github/workflows/linux_unit_tests.yaml
+++ /dev/null
@@ -1,174 +0,0 @@
-name: linux tests
-
-on:
-  push:
-    branches:
-      - develop
-      - releases/**
-  pull_request:
-    branches:
-      - develop
-      - releases/**
-jobs:
-  unittests:
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
-        concretizer: ['original', 'clingo']
-
-    steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-    - uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install System packages
-      run: |
-          sudo apt-get -y update
-          # Needed for unit tests
-          sudo apt-get install -y coreutils gfortran graphviz gnupg2 mercurial
-          sudo apt-get install -y ninja-build patchelf
-          # Needed for kcov
-          sudo apt-get -y install cmake binutils-dev libcurl4-openssl-dev
-          sudo apt-get -y install zlib1g-dev libdw-dev libiberty-dev
-    - name: Install Python packages
-      run: |
-          pip install --upgrade pip six setuptools codecov coverage
-    - name: Setup git configuration
-      run: |
-          # Need this for the git tests to succeed.
-          git --version
-          . .github/workflows/setup_git.sh
-    - name: Install kcov for bash script coverage
-      env:
-          KCOV_VERSION: 34
-      run: |
-          KCOV_ROOT=$(mktemp -d)
-          wget --output-document=${KCOV_ROOT}/${KCOV_VERSION}.tar.gz https://github.com/SimonKagstrom/kcov/archive/v${KCOV_VERSION}.tar.gz
-          tar -C ${KCOV_ROOT} -xzvf ${KCOV_ROOT}/${KCOV_VERSION}.tar.gz
-          mkdir -p ${KCOV_ROOT}/build
-          cd ${KCOV_ROOT}/build && cmake -Wno-dev ${KCOV_ROOT}/kcov-${KCOV_VERSION} && cd -
-          make -C ${KCOV_ROOT}/build && sudo  make -C ${KCOV_ROOT}/build install
-    - name: Bootstrap clingo from sources
-      if: ${{ matrix.concretizer == 'clingo' }}
-      run: |
-          . share/spack/setup-env.sh
-          spack external find --not-buildable cmake bison
-          spack -v solve zlib
-    - name: Run unit tests
-      env:
-          COVERAGE: true
-          SPACK_TEST_SOLVER: ${{ matrix.concretizer }}
-      run: |
-          share/spack/qa/run-unit-tests
-          coverage combine
-          coverage xml
-    - uses: codecov/codecov-action@v1
-      with:
-        flags: unittests,linux,${{ matrix.concretizer }}
-  shell:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-    - uses: actions/setup-python@v2
-      with:
-        python-version: 3.9
-    - name: Install System packages
-      run: |
-          sudo apt-get -y update
-          # Needed for shell tests
-          sudo apt-get install -y coreutils csh zsh tcsh fish dash bash
-          # Needed for kcov
-          sudo apt-get -y install cmake binutils-dev libcurl4-openssl-dev
-          sudo apt-get -y install zlib1g-dev libdw-dev libiberty-dev
-    - name: Install Python packages
-      run: |
-          pip install --upgrade pip six setuptools codecov coverage
-    - name: Setup git configuration
-      run: |
-          # Need this for the git tests to succeed.
-          git --version
-          . .github/workflows/setup_git.sh
-    - name: Install kcov for bash script coverage
-      env:
-          KCOV_VERSION: 38
-      run: |
-          KCOV_ROOT=$(mktemp -d)
-          wget --output-document=${KCOV_ROOT}/${KCOV_VERSION}.tar.gz https://github.com/SimonKagstrom/kcov/archive/v${KCOV_VERSION}.tar.gz
-          tar -C ${KCOV_ROOT} -xzvf ${KCOV_ROOT}/${KCOV_VERSION}.tar.gz
-          mkdir -p ${KCOV_ROOT}/build
-          cd ${KCOV_ROOT}/build && cmake -Wno-dev ${KCOV_ROOT}/kcov-${KCOV_VERSION} && cd -
-          make -C ${KCOV_ROOT}/build && sudo  make -C ${KCOV_ROOT}/build install
-    - name: Run shell tests
-      env:
-          COVERAGE: true
-      run: |
-          share/spack/qa/run-shell-tests
-    - uses: codecov/codecov-action@v1
-      with:
-        flags: shelltests,linux
-
-  centos6:
-    # Test for Python2.6 run on Centos 6
-    runs-on: ubuntu-latest
-    container: spack/github-actions:centos6
-    steps:
-    - name: Run unit tests
-      env:
-          HOME: /home/spack-test
-      run: |
-          whoami && echo $HOME && cd $HOME
-          git clone https://github.com/spack/spack.git && cd spack
-          git fetch origin ${{ github.ref }}:test-branch
-          git checkout test-branch
-          share/spack/qa/run-unit-tests
-
-  rhel8-platform-python:
-    runs-on: ubuntu-latest
-    container: registry.access.redhat.com/ubi8/ubi
-    steps:
-    - name: Install dependencies
-      run: |
-          dnf install -y \
-              bzip2 curl file gcc-c++ gcc gcc-gfortran git gnupg2 gzip \
-              make patch tcl unzip which xz
-    - uses: actions/checkout@v2
-    - name: Setup repo and non-root user
-      run: |
-          git --version
-          git fetch --unshallow
-          . .github/workflows/setup_git.sh
-          useradd spack-test
-          chown -R spack-test .
-    - name: Run unit tests
-      env:
-          SPACK_PYTHON: /usr/libexec/platform-python
-      shell: runuser -u spack-test -- bash {0}
-      run: |
-          source share/spack/setup-env.sh
-          spack unit-test -k 'not svn and not hg' -x --verbose
-  clingo-cffi:
-    # Test for the clingo based solver (using clingo-cffi)
-    runs-on: ubuntu-latest
-    container: spack/github-actions:clingo-cffi
-    steps:
-      - name: Run unit tests
-        run: |
-          whoami && echo PWD=$PWD && echo HOME=$HOME && echo SPACK_TEST_SOLVER=$SPACK_TEST_SOLVER
-          python3 -c "import clingo; print(hasattr(clingo.Symbol, '_rep'), clingo.__version__)"
-          git clone https://github.com/spack/spack.git && cd spack
-          git fetch origin ${{ github.ref }}:test-branch
-          git checkout test-branch
-          . share/spack/setup-env.sh
-          spack compiler find
-          spack solve mpileaks%gcc
-          coverage run $(which spack) unit-test -v
-          coverage combine
-          coverage xml
-      - uses: codecov/codecov-action@v1
-        with:
-          flags: unittests,linux,clingo
diff --git a/.github/workflows/macos_unit_tests.yaml b/.github/workflows/macos_unit_tests.yaml
deleted file mode 100644
index e5918968d2..0000000000
--- a/.github/workflows/macos_unit_tests.yaml
+++ /dev/null
@@ -1,44 +0,0 @@
-name: macos tests
-
-on:
-  push:
-    branches:
-      - develop
-      - releases/**
-  pull_request:
-    branches:
-      - develop
-      - releases/**
-jobs:
-  build:
-    runs-on: macos-latest
-    strategy:
-      matrix:
-        python-version: [3.8]
-    steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-    - uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install Python packages
-      run: |
-          pip install --upgrade pip six setuptools
-          pip install --upgrade codecov coverage
-          pip install --upgrade flake8 pep8-naming mypy
-    - name: Setup Homebrew packages
-      run: |
-        brew install dash fish gcc gnupg2 kcov
-    - name: Run unit tests
-      run: |
-        git --version
-        . .github/workflows/setup_git.sh
-        . share/spack/setup-env.sh
-        coverage run $(which spack) unit-test
-        coverage combine
-        coverage xml
-    - uses: codecov/codecov-action@v1
-      with:
-        file: ./coverage.xml
-        flags: unittests,macos
diff --git a/.github/workflows/style_and_docs.yaml b/.github/workflows/style_and_docs.yaml
deleted file mode 100644
index 0f84e1e885..0000000000
--- a/.github/workflows/style_and_docs.yaml
+++ /dev/null
@@ -1,65 +0,0 @@
-name: style and docs
-
-on:
-  push:
-    branches:
-      - develop
-      - releases/**
-  pull_request:
-    branches:
-      - develop
-      - releases/**
-jobs:
-  validate:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
-      with:
-        python-version: 3.9
-    - name: Install Python Packages
-      run: |
-        pip install --upgrade pip
-        pip install --upgrade vermin
-    - name: Minimum Version (Spack's Core)
-      run: vermin --backport argparse --backport typing -t=2.6- -t=3.5- -v lib/spack/spack/ lib/spack/llnl/ bin/
-    - name: Minimum Version (Repositories)
-      run: vermin --backport argparse --backport typing -t=2.6- -t=3.5- -v var/spack/repos
-  style:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
-    - uses: actions/setup-python@v2
-      with:
-        python-version: 3.9
-    - name: Install Python packages
-      run: |
-        pip install --upgrade pip six setuptools flake8 mypy>=0.800 black
-    - name: Setup git configuration
-      run: |
-        # Need this for the git tests to succeed.
-        git --version
-        . .github/workflows/setup_git.sh
-    - name: Run style tests
-      run: |
-          share/spack/qa/run-style-tests
-  documentation:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
-      with:
-        python-version: 3.9
-    - name: Install System packages
-      run: |
-        sudo apt-get -y update
-        sudo apt-get install -y coreutils ninja-build graphviz
-    - name: Install Python packages
-      run: |
-        pip install --upgrade pip six setuptools
-        pip install --upgrade -r lib/spack/docs/requirements.txt
-    - name: Build documentation
-      run: |
-          share/spack/qa/run-doc-tests
diff --git a/.github/workflows/unit_tests.yaml b/.github/workflows/unit_tests.yaml
new file mode 100644
index 0000000000..7fcd61d9f4
--- /dev/null
+++ b/.github/workflows/unit_tests.yaml
@@ -0,0 +1,337 @@
+name: linux tests
+
+on:
+  push:
+    branches:
+      - develop
+      - releases/**
+  pull_request:
+    branches:
+      - develop
+      - releases/**
+jobs:
+  # Validate that the code can be run on all the Python versions
+  # supported by Spack
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+    - name: Install Python Packages
+      run: |
+        pip install --upgrade pip
+        pip install --upgrade vermin
+    - name: vermin (Spack's Core)
+      run: vermin --backport argparse --backport typing -t=2.6- -t=3.5- -v lib/spack/spack/ lib/spack/llnl/ bin/
+    - name: vermin (Repositories)
+      run: vermin --backport argparse --backport typing -t=2.6- -t=3.5- -v var/spack/repos
+  # Run style checks on the files that have been changed
+  style:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+    - name: Install Python packages
+      run: |
+        pip install --upgrade pip six setuptools flake8 mypy>=0.800 black
+    - name: Setup git configuration
+      run: |
+        # Need this for the git tests to succeed.
+        git --version
+        . .github/workflows/setup_git.sh
+    - name: Run style tests
+      run: |
+          share/spack/qa/run-style-tests
+  # Build the documentation
+  documentation:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+    - name: Install System packages
+      run: |
+        sudo apt-get -y update
+        sudo apt-get install -y coreutils ninja-build graphviz
+    - name: Install Python packages
+      run: |
+        pip install --upgrade pip six setuptools
+        pip install --upgrade -r lib/spack/docs/requirements.txt
+    - name: Build documentation
+      run: |
+          share/spack/qa/run-doc-tests
+
+  # Check which files have been updated by the PR
+  changes:
+    runs-on: ubuntu-latest
+    # Set job outputs to values from filter step
+    outputs:
+      core: ${{ steps.filter.outputs.core }}
+      packages: ${{ steps.filter.outputs.packages }}
+      with_coverage: ${{ steps.coverage.outputs.with_coverage }}
+    steps:
+    # For pull requests it's not necessary to checkout the code
+    - uses: dorny/paths-filter@v2
+      id: filter
+      with:
+        # See https://github.com/dorny/paths-filter/issues/56 for the syntax used below
+        filters: |
+          core:
+          - './!(var/**)/**'
+          packages:
+          - 'var/**'
+    # Some links for easier reference:
+    #
+    # "github" context: https://docs.github.com/en/actions/reference/context-and-expression-syntax-for-github-actions#github-context
+    # job outputs: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjob_idoutputs
+    # setting environment variables from earlier steps: https://docs.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-environment-variable
+    #
+    - id: coverage
+      # Run the subsequent jobs with coverage if this is a PR and core has been modified
+      # or if this workflow is triggered by a push event (this means that once a PR is
+      # merged we'll perform a full run with CI on develop even though the PR was only
+      # modifying packages)
+      run: |
+        echo Core changes: ${{ steps.filter.outputs.core }}
+        echo Event name: ${{ github.event_name }}
+        if [ "${{ steps.filter.outputs.core }}" == "true" ] || [ "${{ github.event_name }}" == 'push' ]
+        then
+          echo "::set-output name=with_coverage::true"
+        else
+          echo "::set-output name=with_coverage::false"
+        fi
+
+  # Run unit tests with different configurations on linux
+  unittests:
+    needs: [ validate, style, documentation, changes ]
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
+        concretizer: ['original', 'clingo']
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install System packages
+      run: |
+          sudo apt-get -y update
+          # Needed for unit tests
+          sudo apt-get install -y coreutils gfortran graphviz gnupg2 mercurial
+          sudo apt-get install -y ninja-build patchelf
+          # Needed for kcov
+          sudo apt-get -y install cmake binutils-dev libcurl4-openssl-dev
+          sudo apt-get -y install zlib1g-dev libdw-dev libiberty-dev
+    - name: Install Python packages
+      run: |
+          pip install --upgrade pip six setuptools codecov coverage
+    - name: Setup git configuration
+      run: |
+          # Need this for the git tests to succeed.
+          git --version
+          . .github/workflows/setup_git.sh
+    - name: Install kcov for bash script coverage
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      env:
+          KCOV_VERSION: 34
+      run: |
+          KCOV_ROOT=$(mktemp -d)
+          wget --output-document=${KCOV_ROOT}/${KCOV_VERSION}.tar.gz https://github.com/SimonKagstrom/kcov/archive/v${KCOV_VERSION}.tar.gz
+          tar -C ${KCOV_ROOT} -xzvf ${KCOV_ROOT}/${KCOV_VERSION}.tar.gz
+          mkdir -p ${KCOV_ROOT}/build
+          cd ${KCOV_ROOT}/build && cmake -Wno-dev ${KCOV_ROOT}/kcov-${KCOV_VERSION} && cd -
+          make -C ${KCOV_ROOT}/build && sudo  make -C ${KCOV_ROOT}/build install
+    - name: Bootstrap clingo from sources
+      if: ${{ matrix.concretizer == 'clingo' }}
+      run: |
+          . share/spack/setup-env.sh
+          spack external find --not-buildable cmake bison
+          spack -v solve zlib
+    - name: Run unit tests (full suite with coverage)
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      env:
+          COVERAGE: true
+          SPACK_TEST_SOLVER: ${{ matrix.concretizer }}
+      run: |
+          share/spack/qa/run-unit-tests
+          coverage combine
+          coverage xml
+    - name: Run unit tests (reduced suite without coverage)
+      if: ${{ needs.changes.outputs.with_coverage == 'false' }}
+      env:
+          ONLY_PACKAGES: true
+          SPACK_TEST_SOLVER: ${{ matrix.concretizer }}
+      run: |
+          share/spack/qa/run-unit-tests
+    - uses: codecov/codecov-action@v1
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      with:
+        flags: unittests,linux,${{ matrix.concretizer }}
+  # Test shell integration
+  shell:
+    needs: [ validate, style, documentation, changes ]
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - uses: actions/setup-python@v2
+      with:
+        python-version: 3.9
+    - name: Install System packages
+      run: |
+          sudo apt-get -y update
+          # Needed for shell tests
+          sudo apt-get install -y coreutils csh zsh tcsh fish dash bash
+          # Needed for kcov
+          sudo apt-get -y install cmake binutils-dev libcurl4-openssl-dev
+          sudo apt-get -y install zlib1g-dev libdw-dev libiberty-dev
+    - name: Install Python packages
+      run: |
+          pip install --upgrade pip six setuptools codecov coverage
+    - name: Setup git configuration
+      run: |
+          # Need this for the git tests to succeed.
+          git --version
+          . .github/workflows/setup_git.sh
+    - name: Install kcov for bash script coverage
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      env:
+          KCOV_VERSION: 38
+      run: |
+          KCOV_ROOT=$(mktemp -d)
+          wget --output-document=${KCOV_ROOT}/${KCOV_VERSION}.tar.gz https://github.com/SimonKagstrom/kcov/archive/v${KCOV_VERSION}.tar.gz
+          tar -C ${KCOV_ROOT} -xzvf ${KCOV_ROOT}/${KCOV_VERSION}.tar.gz
+          mkdir -p ${KCOV_ROOT}/build
+          cd ${KCOV_ROOT}/build && cmake -Wno-dev ${KCOV_ROOT}/kcov-${KCOV_VERSION} && cd -
+          make -C ${KCOV_ROOT}/build && sudo  make -C ${KCOV_ROOT}/build install
+    - name: Run shell tests (without coverage)
+      if: ${{ needs.changes.outputs.with_coverage == 'false' }}
+      run: |
+          share/spack/qa/run-shell-tests
+    - name: Run shell tests (with coverage)
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      env:
+          COVERAGE: true
+      run: |
+          share/spack/qa/run-shell-tests
+    - uses: codecov/codecov-action@v1
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      with:
+        flags: shelltests,linux
+  # Test for Python2.6 run on Centos 6
+  centos6:
+    needs: [ validate, style, documentation ]
+    runs-on: ubuntu-latest
+    container: spack/github-actions:centos6
+    steps:
+    - name: Run unit tests
+      env:
+          HOME: /home/spack-test
+      run: |
+          whoami && echo $HOME && cd $HOME
+          git clone https://github.com/spack/spack.git && cd spack
+          git fetch origin ${{ github.ref }}:test-branch
+          git checkout test-branch
+          share/spack/qa/run-unit-tests
+
+  # Test RHEL8 UBI with platform Python
+  rhel8-platform-python:
+    needs: [ validate, style, documentation ]
+    runs-on: ubuntu-latest
+    container: registry.access.redhat.com/ubi8/ubi
+    steps:
+    - name: Install dependencies
+      run: |
+          dnf install -y \
+              bzip2 curl file gcc-c++ gcc gcc-gfortran git gnupg2 gzip \
+              make patch tcl unzip which xz
+    - uses: actions/checkout@v2
+    - name: Setup repo and non-root user
+      run: |
+          git --version
+          git fetch --unshallow
+          . .github/workflows/setup_git.sh
+          useradd spack-test
+          chown -R spack-test .
+    - name: Run unit tests
+      env:
+          SPACK_PYTHON: /usr/libexec/platform-python
+      shell: runuser -u spack-test -- bash {0}
+      run: |
+          source share/spack/setup-env.sh
+          spack unit-test -k 'not svn and not hg' -x --verbose
+  # Test for the clingo based solver (using clingo-cffi)
+  clingo-cffi:
+    needs: [ validate, style, documentation, changes ]
+    runs-on: ubuntu-latest
+    container: spack/github-actions:clingo-cffi
+    steps:
+      - name: Run unit tests
+        run: |
+          whoami && echo PWD=$PWD && echo HOME=$HOME && echo SPACK_TEST_SOLVER=$SPACK_TEST_SOLVER
+          python3 -c "import clingo; print(hasattr(clingo.Symbol, '_rep'), clingo.__version__)"
+          git clone https://github.com/spack/spack.git && cd spack
+          git fetch origin ${{ github.ref }}:test-branch
+          git checkout test-branch
+          . share/spack/setup-env.sh
+          spack compiler find
+          spack solve mpileaks%gcc
+          coverage run $(which spack) unit-test -v
+          coverage combine
+          coverage xml
+      - uses: codecov/codecov-action@v1
+        if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+        with:
+          flags: unittests,linux,clingo
+  # Run unit tests on MacOS
+  build:
+    needs: [ validate, style, documentation, changes ]
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        python-version: [3.8]
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install Python packages
+      run: |
+          pip install --upgrade pip six setuptools
+          pip install --upgrade codecov coverage
+          pip install --upgrade flake8 pep8-naming mypy
+    - name: Setup Homebrew packages
+      run: |
+        brew install dash fish gcc gnupg2 kcov
+    - name: Run unit tests
+      run: |
+        git --version
+        . .github/workflows/setup_git.sh
+        . share/spack/setup-env.sh
+        if [ "${{ needs.changes.outputs.with_coverage }}" == "true" ]
+        then
+          coverage run $(which spack) unit-test -x
+          coverage combine
+          coverage xml
+        else
+          echo "ONLY PACKAGE RECIPES CHANGED [skipping coverage]"
+          $(which spack) unit-test -x -m "not maybeslow"
+        fi
+    - uses: codecov/codecov-action@v1
+      if: ${{ needs.changes.outputs.with_coverage == 'true' }}
+      with:
+        file: ./coverage.xml
+        flags: unittests,macos
diff --git a/README.md b/README.md
index d4bf01005c..12f0dbe6c0 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,6 @@
 # <img src="https://cdn.rawgit.com/spack/spack/develop/share/spack/logo/spack-logo.svg" width="64" valign="middle" alt="Spack"/> Spack
 
-[![MacOS Tests](https://github.com/spack/spack/workflows/macos%20tests/badge.svg)](https://github.com/spack/spack/actions)
-[![Linux Tests](https://github.com/spack/spack/workflows/linux%20tests/badge.svg)](https://github.com/spack/spack/actions)
+[![Unit Tests](https://github.com/spack/spack/workflows/linux%20tests/badge.svg)](https://github.com/spack/spack/actions)
 [![Linux Builds](https://github.com/spack/spack/workflows/linux%20builds/badge.svg)](https://github.com/spack/spack/actions)
 [![macOS Builds (nightly)](https://github.com/spack/spack/workflows/macOS%20builds%20nightly/badge.svg?branch=develop)](https://github.com/spack/spack/actions?query=workflow%3A%22macOS+builds+nightly%22)
 [![codecov](https://codecov.io/gh/spack/spack/branch/develop/graph/badge.svg)](https://codecov.io/gh/spack/spack)
diff --git a/lib/spack/spack/test/ci.py b/lib/spack/spack/test/ci.py
index 33488a2d8a..dae5066bf8 100644
--- a/lib/spack/spack/test/ci.py
+++ b/lib/spack/spack/test/ci.py
@@ -114,6 +114,7 @@ def test_get_concrete_specs(config, mock_packages):
     assert('archive-files' in spec_map)
 
 
+@pytest.mark.maybeslow
 def test_register_cdash_build():
     build_name = 'Some pkg'
     base_url = 'http://cdash.fake.org'
diff --git a/lib/spack/spack/test/cmd/ci.py b/lib/spack/spack/test/cmd/ci.py
index 24992d78c2..927c1e9ce8 100644
--- a/lib/spack/spack/test/cmd/ci.py
+++ b/lib/spack/spack/test/cmd/ci.py
@@ -38,6 +38,9 @@ buildcache_cmd = spack.main.SpackCommand('buildcache')
 git = exe.which('git', required=True)
 
 
+pytestmark = pytest.mark.maybeslow
+
+
 @pytest.fixture()
 def env_deactivate():
     yield
diff --git a/lib/spack/spack/test/cmd/env.py b/lib/spack/spack/test/cmd/env.py
index 592d8f451c..5665b41fac 100644
--- a/lib/spack/spack/test/cmd/env.py
+++ b/lib/spack/spack/test/cmd/env.py
@@ -25,8 +25,10 @@ from spack.util.path import substitute_path_variables
 
 
 # everything here uses the mock_env_path
-pytestmark = pytest.mark.usefixtures(
-    'mutable_mock_env_path', 'config', 'mutable_mock_repo')
+pytestmark = [
+    pytest.mark.usefixtures('mutable_mock_env_path', 'config', 'mutable_mock_repo'),
+    pytest.mark.maybeslow
+]
 
 env        = SpackCommand('env')
 install    = SpackCommand('install')
diff --git a/lib/spack/spack/test/cmd/url.py b/lib/spack/spack/test/cmd/url.py
index f2466dcdf2..c130840984 100644
--- a/lib/spack/spack/test/cmd/url.py
+++ b/lib/spack/spack/test/cmd/url.py
@@ -71,7 +71,7 @@ def test_url_with_no_version_fails():
         url('parse', 'http://www.netlib.org/voronoi/triangle.zip')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 @pytest.mark.skipif(
     sys.version_info < (2, 7),
     reason="Python 2.6 tests are run in a container, where "
@@ -106,7 +106,7 @@ def test_url_list():
     assert 0 < correct_version_urls < total_urls
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 @pytest.mark.skipif(
     sys.version_info < (2, 7),
     reason="Python 2.6 tests are run in a container, where "
diff --git a/lib/spack/spack/test/cmd/versions.py b/lib/spack/spack/test/cmd/versions.py
index e4bf711a8a..0d6f53833c 100644
--- a/lib/spack/spack/test/cmd/versions.py
+++ b/lib/spack/spack/test/cmd/versions.py
@@ -14,7 +14,6 @@ def test_safe_only_versions():
     """Only test the safe versions of a package.
        (Using the deprecated command line argument)
     """
-
     versions('--safe-only', 'zlib')
 
 
@@ -24,21 +23,21 @@ def test_safe_versions():
     versions('--safe', 'zlib')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_remote_versions():
     """Test a package for which remote versions should be available."""
 
     versions('zlib')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_remote_versions_only():
     """Test a package for which remote versions should be available."""
 
     versions('--remote', 'zlib')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 @pytest.mark.usefixtures('mock_packages')
 def test_new_versions_only():
     """Test a package for which new versions should be available."""
@@ -46,28 +45,28 @@ def test_new_versions_only():
     versions('--new', 'brillig')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_no_versions():
     """Test a package for which no remote versions are available."""
 
     versions('converge')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_no_unchecksummed_versions():
     """Test a package for which no unchecksummed versions are available."""
 
     versions('bzip2')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_versions_no_url():
     """Test a package with versions but without a ``url`` attribute."""
 
     versions('graphviz')
 
 
-@pytest.mark.network
+@pytest.mark.maybeslow
 def test_no_versions_no_url():
     """Test a package without versions or a ``url`` attribute."""
 
diff --git a/lib/spack/spack/test/util/util_gpg.py b/lib/spack/spack/test/util/util_gpg.py
index b8adbc537d..987dcf7f0e 100644
--- a/lib/spack/spack/test/util/util_gpg.py
+++ b/lib/spack/spack/test/util/util_gpg.py
@@ -65,6 +65,7 @@ fpr:::::::::ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ:"""
 
 @pytest.mark.skipif(not spack.util.gpg.GpgConstants.user_run_dir,
                     reason='This test requires /var/run/user/$(id -u)')
+@pytest.mark.requires_executables('gpg2')
 def test_really_long_gnupg_home_dir(tmpdir):
     N = 960
 
diff --git a/pytest.ini b/pytest.ini
index baf163ef0b..71f563954a 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,10 +1,9 @@
 # content of pytest.ini
 [pytest]
-addopts = --durations=20 -ra
+addopts = --durations=30 -ra
 testpaths = lib/spack/spack/test
 python_files = *.py
 markers =
   db: tests that require creating a DB
-  network: tests that require access to the network
   maybeslow: tests that may be slow (e.g. access a lot the filesystem, etc.)
   regression: tests that fix a reported bug
diff --git a/share/spack/qa/run-shell-tests b/share/spack/qa/run-shell-tests
index 8890b67d42..83838ff5ef 100755
--- a/share/spack/qa/run-shell-tests
+++ b/share/spack/qa/run-shell-tests
@@ -18,7 +18,11 @@
 ORIGINAL_PATH="$PATH"
 
 . "$(dirname $0)/setup.sh"
-check_dependencies $coverage kcov git hg svn
+if [ "$COVERAGE" = true ]; then
+  check_dependencies $coverage kcov git hg svn
+else
+  echo "COVERAGE not set to 'true' [skipping coverage]"
+fi
 
 # Clean the environment by removing Spack from the path and getting rid of
 # the spack shell function
diff --git a/share/spack/qa/run-unit-tests b/share/spack/qa/run-unit-tests
index 81d9abe247..6cef3cf679 100755
--- a/share/spack/qa/run-unit-tests
+++ b/share/spack/qa/run-unit-tests
@@ -42,4 +42,9 @@ spack -p --lines 20 spec mpileaks%gcc ^elfutils@0.170
 #-----------------------------------------------------------
 # Run unit tests with code coverage
 #-----------------------------------------------------------
+if [[ "$ONLY_PACKAGES" == "true" ]]; then
+  echo "ONLY PACKAGE RECIPES CHANGED [skipping slow unit tests]"
+  export PYTEST_ADDOPTS='-m "not maybeslow"'
+fi
+
 $coverage_run $(which spack) unit-test -x --verbose