Run integration tests

Run integration tests only on macOS for now, because on Windows and
Ubuntu integration tests get stuck and time out after six hours.

.github/workflows/ci.yml

@@ -82,3 +82,65 @@ jobs:
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           file: coverage.xml
+
+  integration:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - macos-latest
+        python-version:
+          - 2.7
+
+    steps:
+
+      - name: [Ubuntu] Install Tor
+        if: matrix.os == 'ubuntu-latest'
+        run: sudo apt install tor
+
+      - name: [macOS] Install Tor
+        if: matrix.os == 'macos-latest'
+        run: brew install tor
+
+      - name: [Windows] Install Tor
+        if: matrix.os == 'windows-latest'
+        uses: crazy-max/ghaction-chocolatey@v1
+        with:
+          args: install tor
+
+      - name: Install MSVC 9.0 for Python 2.7 [Windows]
+        if: matrix.os == 'windows-latest' && matrix.python-version == '2.7'
+        uses: crazy-max/ghaction-chocolatey@v1
+        with:
+          args: install vcpython27
+
+      - name: Check out Tahoe-LAFS sources
+        uses: actions/checkout@v2
+
+      - name: Fetch all history for all tags and branches
+        run: git fetch --prune --unshallow
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v1
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install Python packages
+        run: |
+          pip install --upgrade tox
+          pip list
+
+      - name: Display tool versions
+        run: python misc/build_helpers/show-tool-versions.py
+
+      - name: Run "tox -e integration"
+        run: tox -e integration
+
+      - name: Upload eliot.log in case of failure
+        uses: actions/upload-artifact@v1
+        if: failure()
+        with:
+          name: eliot.log
+          path: eliot.log
+