CI: add a build against numpy nightly

.github/workflows/test.yml

@@ -23,17 +23,23 @@ jobs:
           python-version: 3.9
       - uses: pre-commit/[email protected]
   build:
-    name: ${{ matrix.os }} Python ${{ matrix.python-version }}
+    name: ${{ matrix.os }} Python ${{ matrix.python-version }} numpy-nightly=${{ matrix.numpy-nightly }}
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         os: ["ubuntu-latest"]
         python-version: ["3.9", "3.10", "3.11", "3.12"]
+        numpy-nightly: [false]
         include:
+          - os: ubuntu-latest
+            python-version: "3.12"
+            numpy-nightly: true
           - os: macOS-11
             python-version: "3.11"
+            numpy-nightly: false
           - os: windows-2019
             python-version: "3.11"
+            numpy-nightly: false
 
     steps:
       - uses: actions/checkout@v3
@@ -43,10 +49,20 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Install dependencies with numpy nightly
+        if: ${{ matrix.numpy-nightly == true }}
+        run: |
+            python -m pip install --upgrade pip
+            python -m pip install -U --pre numpy \
+              -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
+            python -c "import numpy; print(f'{numpy.__version__=}')"
+            python -m pip install setuptools
+            python -m pip install .[dev] --no-build-isolation
       - name: Install dependencies
+        if: ${{ matrix.numpy-nightly == false }}
         run: |
           python -m pip install --upgrade pip
-          pip install .[dev]
+          python -m pip install .[dev]
       - name: Run tests
         run: |
           pytest -n auto

ml_dtypes/tests/custom_float_test.py

@@ -37,6 +37,14 @@
 float8_e5m2fnuz = ml_dtypes.float8_e5m2fnuz
 
 
+try:
+  # numpy >= 2.0
+  ComplexWarning = np.exceptions.ComplexWarning
+except AttributeError:
+  # numpy < 2.0
+  ComplexWarning = np.ComplexWarning
+
+
 @contextlib.contextmanager
 def ignore_warning(**kw):
   with warnings.catch_warnings():
@@ -703,7 +711,7 @@ def testCasts(self, float_type):
       self.assertTrue(np.all(x == z))
       self.assertEqual(dtype, z.dtype)
 
-  @ignore_warning(category=np.ComplexWarning)
+  @ignore_warning(category=ComplexWarning)
   def testConformNumpyComplex(self, float_type):
     for dtype in [np.complex64, np.complex128, np.clongdouble]:
       x = np.array([1.5, 2.5 + 2.0j, 3.5], dtype=dtype)

pytest.ini

@@ -1,3 +1,4 @@
 [pytest]
 filterwarnings =
     error
+    ignore:numpy.core._multiarray_umat.*:DeprecationWarning