Add unit testing workflow (#34)

Closes #33.

.github/workflows/code_check.yml

@@ -1,6 +1,10 @@
 name: Code Checking
 on:
   push:
+    branches: main
+  pull_request:
+    paths:
+      - "**.dart"
 
 jobs:
   code-check:

.github/workflows/unit_testing.yaml

@@ -0,0 +1,47 @@
+name: Unit Testing
+
+on:
+  pull_request:
+    paths:
+      - "package/lib/**"
+      - "package/test/**"
+
+jobs:
+  test:
+    name: Unit Tests
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      actions: read
+      checks: write
+    defaults:
+      run:
+        working-directory: package/
+    env:
+      FLUTTER_TEST_REPORT: ${{github.workspace}}/flutter-test-report.json
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+          flutter-version: 3.x
+
+      - name: Flutter version
+        run: flutter --version
+
+      - name: Get dependencies
+        run: flutter pub get
+
+      - name: Run unit tests
+        run: flutter test --file-reporter="json:${{ env.FLUTTER_TEST_REPORT }}"
+
+      - name: Write test report
+        uses: dorny/test-reporter@v1
+        if: success() || failure()
+        with:
+          name: Test Report
+          path: ${{ env.FLUTTER_TEST_REPORT }}
+          reporter: flutter-json

package/test/foundation/sheet_physics_test.dart

@@ -178,4 +178,59 @@ void main() {
       );
     });
   });
+
+  group('$SnapToNearestEdge', () {
+    late SnapToNearestEdge behaviorUnderTest;
+
+    setUp(() {
+      behaviorUnderTest = const SnapToNearestEdge(minFlingSpeed: 50);
+    });
+
+    test('snaps to the nearest edge if the velocity is small enough', () {
+      final positionAtNearTopEdge = _referenceSheetMetrics.copyWith(
+        pixels: _referenceSheetMetrics.maxPixels - 50,
+      );
+      final positionAtNearBottomEdge = _referenceSheetMetrics.copyWith(
+        pixels: _referenceSheetMetrics.minPixels + 50,
+      );
+
+      expect(
+        behaviorUnderTest.findSnapPixels(0, positionAtNearTopEdge),
+        moreOrLessEquals(_referenceSheetMetrics.maxPixels),
+      );
+      expect(
+        behaviorUnderTest.findSnapPixels(0, positionAtNearBottomEdge),
+        moreOrLessEquals(_referenceSheetMetrics.minPixels),
+      );
+    });
+
+    test('is aware of fling gesture direction', () {
+      expect(
+        behaviorUnderTest.findSnapPixels(50, _positionAtBottomEdge),
+        moreOrLessEquals(_referenceSheetMetrics.maxPixels),
+      );
+      expect(
+        behaviorUnderTest.findSnapPixels(-50, _positionAtTopEdge),
+        moreOrLessEquals(_referenceSheetMetrics.minPixels),
+      );
+    });
+
+    test('is disabled if position is out of bounds', () {
+      final overDraggedPosition = _referenceSheetMetrics.copyWith(
+        pixels: _referenceSheetMetrics.maxPixels + 10,
+      );
+      final underDraggedPosition = _referenceSheetMetrics.copyWith(
+        pixels: _referenceSheetMetrics.minPixels - 10,
+      );
+
+      expect(
+        behaviorUnderTest.findSnapPixels(0, overDraggedPosition),
+        isNull,
+      );
+      expect(
+        behaviorUnderTest.findSnapPixels(0, underDraggedPosition),
+        isNull,
+      );
+    });
+  });
 }