Adding testing to the CI.

.github/workflows/test.yml

@@ -0,0 +1,48 @@
+name: Run tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest # arm64 (Apple Silicon)
+          - macos-13  # latest Intel release
+          - windows-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.9"
+      - name: Force numpy < 2 on MacOS Intel
+        if: matrix.os == 'macos-13'
+        run: pip install 'numpy<2'
+      - name: Install 
+        run: |
+          pip install -e .
+          pip install pytest-notebook
+          pre-commit run --all
+          pre-commit install
+      - name: Test import
+        run: |
+          python -c "import ipyniivue"
+      - name: Test
+        run: |
+          coverage run -m pytest --nb-test-files
+      - name: Upload coverage to codecov (Only do this for the ubuntu-latest job)
+        if: matrix.os == 'ubuntu-latest'
+        uses: codecov/codecov-action@v3
+        with:
+          token: ${{secrets.CODECOV_TOKEN}}