diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8d3ed21..9fd4a20 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,55 +1,291 @@
-name: Publish to GitHub Package Registry
+name: "/setup"
+on:
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - "**.md"
+  pull_request:
+    paths-ignore:
+      - "**.md"
+  workflow_dispatch:
 
-on: [push]
+defaults:
+  run:
+    shell: bash
 
 jobs:
-  build:
+  test:
+    name: Unit Tests - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v3
+        with:
+          node-version: "16"
+          cache: "npm"
+          cache-dependency-path: package-lock.json
+      - run: npm ci --prefer-offline --no-audit --progress=false
+      - run: npm run bundle
+      - run: npm test
+      - name: Ensure generated files are up-to-date
+        run: git diff --exit-code dist/ lib/
+
+  install-haskell:
+    name: GHC ${{ matrix.plan.ghc }}, Cabal ${{ matrix.plan.cabal }} - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+
+      # Let's see how the other installs are doing and not fail on the first
+      fail-fast: false
+
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+        plan:
+          # Latest releases
+          - ghc:   latest
+            cabal: latest
+          # Latest ghc with cabal head
+          - ghc:   latest
+            cabal: head
+          # Recommended releases (update according to ghcup)
+          # 9.4 will be recommended soon
+          - ghc:   "9.4"
+            cabal: "3.8"
+          - ghc:   "9.2"
+            cabal: "3.6"
+          # Some previously recommended releases of ghc with matching cabal
+          - ghc:   "8.10"
+            cabal: "3.2"
+          - ghc:   "8.8"
+            cabal: "3.0"
+              # cabal-3.0 install might have the Windows symlinking problem
+              # https://github.com/haskell/cabal/issues/5748
+          - ghc:   "8.6"
+            cabal: "2.4"
+        cabal_update: ["false"]
+        # The following tests do not set 'cabal-update', which defaults to 'true' then.
 
-    runs-on: ubuntu-latest
+        include:
+
+          # Test #210 (XDG): is the cabal store-dir set to something meaningful?
+          - os:  ubuntu-latest
+            plan:
+              ghc:   "9.6"
+              cabal: "3.10"
+            cabal_update: "true"
+          # With choco, cabal 3.10.1.0 should map to 3.10.1.1
+          - os:  windows-latest
+            plan:
+              ghc:   "9.6"
+              cabal: "3.10"
+            cabal_update: "true"
+
+          # Test some old versions
+          - os: ubuntu-latest
+            plan:
+              ghc:   "8.2.2"
+              cabal: "2.4.1.0"
+            cabal_update: "false"
+          - os: ubuntu-20.04
+            plan:
+              ghc:   "7.4.2"
+              cabal: "3.4"
+              # ubuntu-20.04/hvr has of GHC 7 just 7.0.1, 7.0.4, 7.2.2, 7.4.2, 7.10.3
+              # and of cabal just 2.4, 3.0, 3.2, 3.4
+              # according to https://launchpad.net/~hvr/+archive/ubuntu/ghc?field.series_filter=focal
+
+          # Test ghcup pre-release channel
+          - os: ubuntu-latest
+            ghcup_release_channel: "https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml"
+            plan:
+              ghc:   "9.6.0.20230111"
+              cabal: "3.8"
+
+          # Test ghc nightly
+          - os: ubuntu-latest
+            ghcup_release_channel: "https://ghc.gitlab.haskell.org/ghcup-metadata/ghcup-nightlies-0.0.7.yaml"
+            plan:
+              ghc:   "latest-nightly"
+              cabal: "latest"
+
+          # setup does something special for 7.10.3 (issue #79)
+          - os: ubuntu-20.04
+            plan:
+              ghc:   "7.10.3"
+              cabal: "3.6"
+          - os: macOS-latest
+            plan:
+              ghc:   "7.10.3"
+              cabal: "3.4"
+
+          # Andreas 2022-12-29, issue #98: GHC 7.10 failed to install on windows (choco)
+          - os: windows-latest
+            plan:
+              ghc:   "7.10"
+              cabal: "3.0"
+
+          # Test for issue #129: GHC 9.4.3 failed to install on windows (choco)
+          - os: windows-latest
+            plan:
+              ghc:   "9.4.3"
+              cabal: "3.8.1.0"
+
+          # Test ghcup on windows (PR #206) which choco does not have 9.4.5
+          - os: windows-latest
+            plan:
+              ghc:   "9.4.5"
+              cabal: "3.8"
+
+          # Test GHC 9.4.4 on windows (Issue #245)
+          - os: windows-latest
+            plan:
+              ghc:   "9.4.4"
+              cabal: "3.10.1.0"
 
     steps:
-    - uses: actions/checkout@v1
-    - name: Use Node.js 14.x
-      uses: actions/setup-node@v1
-      with:
-        registry-url: https://npm.pkg.github.com/
-        node-version: 14.x
-        scope: '@dalenguyen'
-    - name: npm install, build, and test
-      run: |
-        npm install
-        npm run build --if-present
-        npm test      
-    - name: publish
-      env:
-        NODE_AUTH_TOKEN: ${{ secrets.PERSONAL_ACCESS_TOKEN }}
-      run: |
-        npm run deploy
-- name: Test
-
-on: [push, pull_request]
-
-permissions:
-  contents: read
+      - uses: actions/checkout@v4
 
-jobs:
-  test:
+      - uses: ./
+        id: setup
+        with:
+          ghc-version: ${{ matrix.plan.ghc }}
+          ghcup-release-channel: ${{ matrix.ghcup_release_channel }}
+          cabal-version: ${{ matrix.plan.cabal }}
+          cabal-update: ${{ matrix.cabal_update }}
+
+      - name: Show installed versions and PATH
+        run: |
+          cabal --version
+          ghc --version
+          echo "$PATH"
+
+      - name: Confirm resolved and installed versions match
+        shell: bash
+        run: |
+          CABALVER="$(cabal --numeric-version)"
+          GHCVER="$(ghc --numeric-version)"
+          echo "CABALVER=${CABALVER}" >> "${GITHUB_ENV}"
+          echo "GHCVER=${GHCVER}"     >> "${GITHUB_ENV}"
+          if [[ "${{ steps.setup.outputs.ghc-version }}" == "latest-nightly" ]]
+          then
+            GHCVER_EXPECTED=$( \
+              curl "${{ matrix.ghcup_release_channel }}" | \
+              yq '.ghcupDownloads.GHC[] | select(.viTags[] | contains("LatestNightly")) | key' \
+            )
+            echo "Latest nightly: ${GHCVER_EXPECTED}"
+          else
+            GHCVER_EXPECTED="${{ steps.setup.outputs.ghc-version }}"
+          fi
+          if [[ "${{ steps.setup.outputs.cabal-version }}" == "head" ]]
+          then
+            CABALVER_EXPECTED=$( \
+              curl --silent https://raw.githubusercontent.com/haskell/cabal/master/cabal-install/cabal-install.cabal | \
+              sed -E -n 's/^Version:[[:space:]]+//p' \
+            )
+            echo "Cabal head: ${CABALVER_EXPECTED}"
+          else
+            CABALVER_EXPECTED="${{ steps.setup.outputs.cabal-version }}"
+          fi
+          [[ "${CABALVER_EXPECTED}" == ${CABALVER}* ]] && \
+            [[ "${GHCVER}" == "${GHCVER_EXPECTED}" ]]
+
+      - name: Test runghc
+        run: |
+          runghc --version
+          runghc __tests__/hello.hs
+
+      - name: Build test project
+        working-directory: __tests__/project
+        run: cabal build
+
+      - name: Run test project
+        working-directory: __tests__/project
+        run: cabal run
+
+      - name: Install test project
+        working-directory: __tests__/project
+        run: cabal install
+
+      - name: Run installed test project
+        run: hello-haskell-setup
+        # This tests whether the default installdir has been added to the PATH (issue #130).
+
+      - name: Build and run test with Hackage dependency
+        if:   ${{ matrix.cabal_update != 'false' }}
+        working-directory: __tests__/project-with-hackage-dependency
+        run:  cabal build && cabal run
+
+      - name: Confirm installed and expected versions match
+        shell: bash
+        # check that if given in the matrix, the actual version matches:
+        # - cabal: major version
+        # - ghc: major and minor version
+        # pure bash startsWith
+        run: |
+          if [[ "${{ matrix.plan.cabal }}" =~ ^([0-9]+\.[0-9]+) ]]; then cabalmajor="${BASH_REMATCH[1]}"; fi
+          if [[ "${{ matrix.plan.ghc }}" =~ ^([0-9]+\.[0-9]+) ]]; then ghcmajor="${BASH_REMATCH[1]}"; fi
+          if [[ "${{ matrix.plan.ghc }}" =~ ^([0-9]+\.[0-9]+\.[0-9]+) ]]; then ghcver="${BASH_REMATCH[1]}"; fi
+          [[ "${CABALVER}" =~ ^"${cabalmajor}" ]] && [[ "${GHCVER}" =~ ^"${ghcmajor}" ]] && [[ "${GHCVER}" =~ ^"${ghcver}" ]]
+
+  test-fallback:
+    name: Test GHC Installation Fallbacks - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        id: setup
+        env:
+          RUNNER_DEBUG: "1"
+        with:
+          ghc-version: 8.21.5
+      - name: Error on success
+        if: steps.setup.outputs.failed != 'true'
+          # NB: 'failed' is an undeclared output of the setup action, used in debug mode
+        run: |
+          echo "Error: ghc 8.21.5 didn't fail to install"
+
+  install-stack:
+    name: Stack ${{ matrix.stack }} ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+        stack: ["latest", "2.9.3"]
+
     steps:
-    - uses: actions/checkout@v4
-      with:
-        fetch-depth: 0
-    - name: Install bats
-      run: git clone --depth 1 https://github.com/sstephenson/bats.git
-    - name: Run tests
-      run: PATH="./bats/bin:$PATH" script/test
-    - name: Verify download URL checksums
-      if: github.event_name == 'pull_request'
-      run: ./script/mirror verify "$COMMIT_RANGE"
-      env:
-        COMMIT_RANGE: ${{ github.event.pull_request.base.sha }}..
-        
+      - uses: actions/checkout@v4
+
+      - uses: ./
+        id: setup
+        with:
+          enable-stack: true
+          stack-no-global: true
+          stack-version: ${{ matrix.stack }}
+
+      - run: |
+          stack --version
+          stack --help
+
+      - name: Checking if returned stack-root output is correct
+        shell: bash
+          # NB: we invoke `stack path` twice, because the first time it
+          # might install things (like MSYS2 on Windows) which clobber the output.
+        run: |
+          stack path --system-ghc
+          expected_stack_root=$(stack path --system-ghc --stack-root)
+
+          if [ "${expected_stack_root}" != "${{ steps.setup.outputs.stack-root }}" ]; then
+            echo "Stack-root does not match expected value"
+            echo "Expected stack-root: ${expected_stack_root}"
+            echo "Returned stack-root: ${{ steps.setup.outputs.stack-root }}"
+            exit 1
+          fi
+