Analyze and test with both lowest and highest supported Flutter SDK v…

…ersions in CI (#235)

## Related issues (optional)

Closes #229.

## Description

The workflow file was updated to run unit tests and static analysis for
both the lowest and highest supported Flutter SDK versions. This
approach helps detect potential compatibility issues across the entire
supported SDK range. For example, issue #144 stemmed from accidentally
using newly added APIs in Flutter 3.22 that don't exist in lower
versions, while issue #233 arose due to a breaking change introduced in
Flutter 3.24.


## Summary (check all that apply)

- [ ] Modified / added code
- [ ] Modified / added tests
- [ ] Modified / added examples
- [x] Modified / added others (pubspec.yaml, workflows, etc...)
- [ ] Updated README
- [ ] Contains breaking changes
  - [ ] Created / updated migration guide
- [ ] Incremented version number
  - [ ] Updated CHANGELOG

.github/actions/setup_flutter/action.yaml

@@ -6,6 +6,10 @@ inputs:
     description: "The working directory where the Flutter project is located."
     required: false
     default: "."
+  version:
+    description: "The version of Flutter to install."
+    required: false
+    default: "3.x"
 
 runs:
   using: "composite"
@@ -14,7 +18,7 @@ runs:
       uses: subosito/flutter-action@v2
       with:
         channel: stable
-        flutter-version: 3.x
+        flutter-version: ${{ inputs.version }}
         cache: true
 
     - name: Flutter version

.github/workflows/code_check.yaml

@@ -9,35 +9,63 @@ env:
   PATTERN_CHECKER: ${{github.workspace}}/scripts/pattern_checker.sh
 
 jobs:
-  # Change detection
-  changes:
+  setup:
     runs-on: ubuntu-latest
     permissions:
       pull-requests: read
     outputs:
-      flutter-files: ${{ steps.filter.outputs.flutter-files }}
+      flutter-file-changed: ${{ steps.filter.outputs.flutter-file-changed }}
+      lowest-flutter-version: ${{ steps.flutter-version-constraint.outputs.lowest }}
+      highest-flutter-version: ${{ steps.flutter-version-constraint.outputs.highest }}
     steps:
       - uses: actions/checkout@v4
-      - uses: dorny/paths-filter@v3
+
+      - name: Filter changed files
+        uses: dorny/paths-filter@v3
         id: filter
         with:
           filters: |
-            flutter-files:
+            flutter-file-changed:
               - '**.dart'
               - 'pubspec.yaml'
               - 'pubspec.lock'
 
-  # Static code analysis
+      - name: Get Flutter SDK version constraint
+        id: flutter-version-constraint
+        run: |
+          sdk_constraint=$(cat pubspec.yaml | yq .environment.flutter)
+          lowest=$(echo "$sdk_constraint" | grep -oP '(?<=\>=)[0-9]+\.[0-9]+\.[0-9]+' | head -1)
+          highest=$(echo "$sdk_constraint" | grep -oP '(?<=\<)[0-9]+\.[0-9]+\.[0-9]+' | head -1)
+          # If no upper bound is specified, default to 3.x
+          if [ -z "$highest" ]; then
+            highest="3.x"
+          fi
+          echo "lowest=$lowest" >> "$GITHUB_OUTPUT"
+          echo "highest=$highest" >> "$GITHUB_OUTPUT"
+
+      - name: Print output values
+        run: |
+          echo "flutter-file-changed=${{ steps.filter.outputs.flutter-file-changed }}"
+          echo "lowest-flutter-version=${{ steps.flutter-version-constraint.outputs.lowest }}"
+          echo "highest-flutter-version=${{ steps.flutter-version-constraint.outputs.highest }}"
+
   analysis:
-    needs: changes
-    if: ${{ needs.changes.outputs.flutter-files == 'true' }}
+    needs: setup
+    if: ${{ needs.setup.outputs.flutter-file-changed == 'true' }}
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        flutter-version:
+          - ${{ needs.setup.outputs.lowest-flutter-version }}
+          - ${{ needs.setup.outputs.highest-flutter-version }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
       - name: Setup Flutter
         uses: ./.github/actions/setup_flutter
+        with:
+          version: ${{ matrix.flutter-version }}
 
       - name: Format
         run: dart format . -o none --set-exit-if-changed
@@ -48,21 +76,27 @@ jobs:
       - name: Disallowed patterns check
         run: bash ${{ env.PATTERN_CHECKER }} "*.dart" "--" "debugPrint"
 
-  # Unit testing
   testing:
-    needs: changes
-    if: ${{ needs.changes.outputs.flutter-files == 'true' }}
+    needs: setup
+    if: ${{ needs.setup.outputs.flutter-file-changed == 'true' }}
     runs-on: ubuntu-latest
     permissions:
       contents: read
       actions: read
       checks: write
+    strategy:
+      matrix:
+        flutter-version:
+          - ${{ needs.setup.outputs.lowest-flutter-version }}
+          - ${{ needs.setup.outputs.highest-flutter-version }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
       - name: Setup Flutter
         uses: ./.github/actions/setup_flutter
+        with:
+          version: ${{ matrix.flutter-version }}
 
       - name: Run unit tests
         run: flutter test --file-reporter="json:${{ env.FLUTTER_TEST_REPORT }}"
@@ -72,7 +106,7 @@ jobs:
         # PRs from forks have no write permissions.
         if: github.event.pull_request.head.repo.fork == false && (success() || failure())
         with:
-          name: Test Report
+          name: Test Report (with Flutter ${{ matrix.flutter-version }})
           path: ${{ env.FLUTTER_TEST_REPORT }}
           reporter: flutter-json