ENH, CI: Add emscripten to CI

.github/workflows/emscripten.yml

@@ -0,0 +1,68 @@
+# To enable this workflow on a fork, comment out:
+#
+# if: github.repository == 'numpy/numpy'
+name: Test Emscripten/Pyodide build
+
+on:
+  pull_request:
+    branches:
+      - main
+      - maintenance/**
+
+jobs:
+  build-wasm-emscripten:
+    runs-on: ubuntu-latest
+    if: github.repository == 'numpy/numpy'
+    env:
+      PYODIDE_VERSION: 0.22.0a3
+      # PYTHON_VERSION and EMSCRIPTEN_VERSION are determined by PYODIDE_VERSION.
+      # The appropriate versions can be found in the Pyodide repodata.json
+      # "info" field, or in Makefile.envs:
+      # https://github.com/pyodide/pyodide/blob/main/Makefile.envs#L2
+      PYTHON_VERSION: 3.10.2
+      EMSCRIPTEN_VERSION: 3.1.24
+      NODE_VERSION: 18
+    steps:
+      - name: Checkout numpy
+        uses: actions/checkout@v3
+        with:
+          submodules: true
+          # versioneer.py requires the latest tag to be reachable. Here we
+          # fetch the complete history to get access to the tags.
+          # A shallow clone can work when the following issue is resolved:
+          # https://github.com/actions/checkout/issues/338
+          fetch-depth: 0
+
+      - name: set up python
+        id: setup-python
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+
+      - uses: mymindstorm/setup-emsdk@v11
+        with:
+          version: ${{ env.EMSCRIPTEN_VERSION }}
+          actions-cache-folder: emsdk-cache
+
+      - name: Install pyodide-build
+        run: pip install pyodide-build==$PYODIDE_VERSION
+
+      - name: Build
+        run: CFLAGS=-g2 LDFLAGS=-g2 pyodide build
+
+      - name: set up node
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Set up Pyodide virtual environment
+        run: |
+          pyodide venv .venv-pyodide
+          source .venv-pyodide/bin/activate
+          pip install dist/*.whl
+          pip install -r test_requirements.txt
+      - name: Test
+        run: |
+          source .venv-pyodide/bin/activate
+          cd ..
+          python numpy/runtests.py -n -vv