Re-enabled Linux tests with Swift 5.5 installation

.github/workflows/tests.yml

@@ -29,11 +29,25 @@ jobs:
   # Even more hopefully that I won't git blame this comment in the future and see it was 5 years ago :)
   # Some more info on part of the breakage is here: https://forums.swift.org/t/swift-6-0-regression-cannot-inherit-from-some-foundation-classes-on-linux-because-it-has-overridable-members-that-could-not-be-loaded/74794
 
-  # linux:
-  #   name: "Test (Linux)"
-  #   runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      # Install Swift 5.5 in the Linux environment
+      - name: Install Swift 5.5
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y curl libssl-dev
+          git clone https://github.com/kylef/swiftenv.git ~/.swiftenv
+          echo 'export SWIFTENV_ROOT="$HOME/.swiftenv"' >> ~/.bashrc
+          echo 'export PATH="$SWIFTENV_ROOT/bin:$PATH"' >> ~/.bashrc
+          echo 'eval "$(swiftenv init -)"' >> ~/.bashrc
+          export SWIFTENV_ROOT="$HOME/.swiftenv"
+          export PATH="$SWIFTENV_ROOT/bin:$PATH"
+          eval "$(swiftenv init -)"
+          swiftenv install 5.5
+          swiftenv global 5.5
+          swift --version
 
-  #   steps:
-  #     - uses: actions/checkout@v3
-  #     - name: Run tests
-  #       run: CI=1 ./scripts/all-tests.sh "Unix"
+      # Run tests in the Unix/Linux environment
+      - name: Run tests
+        run: CI=1 ./scripts/all-tests.sh "Unix"