Add CI workflow and a network test marker

Author: C1587S

.github/workflows/ci.yml

@@ -0,0 +1,32 @@
+name: tests
+
+on: [push, pull_request]
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: pip
+          cache-dependency-path: pyproject.toml
+      - name: Install the package with all extras
+        run: pip install ".[netcdf,bigquery,dask,dev]"
+      # The suite prints a COVERAGE GAP banner when an optional module
+      # is missing and its tests silently skip. All extras are
+      # installed above, so a banner means the pass count excludes
+      # code this run was meant to cover; fail on it.
+      - name: Run the suite
+        run: |
+          set -o pipefail
+          pytest tests 2>&1 | tee pytest.log
+          if grep -q "COVERAGE GAP" pytest.log; then
+            echo "coverage gap: an optional module is missing"
+            exit 1
+          fi

pyproject.toml

@@ -67,5 +67,6 @@ testpaths = ["tests"]
 markers = [
     "bigquery: tests that contact BigQuery; require credentials and cilresearch context",
     "dask: tests that spin up a real Dask LocalCluster; skipped by default to keep the suite fast",
+    "network: tests that reach the internet; excluded by default so the suite runs offline",
 ]
-addopts = "-ra --strict-markers -m 'not bigquery and not dask'"
+addopts = "-ra --strict-markers -m 'not bigquery and not dask and not network'"