add test and coverage reports (#1)

Run unit tests via GitHub actions and report coverage to Codecov.

.github/workflows/test.yml

@@ -0,0 +1,37 @@
+name: Test
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+jobs:
+  tests:
+    name: Tests
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install ".[test]"
+      - run: pytest --pyargs angst
+      - run: pytest --import-mode prepend --doctest-modules src/
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v4
+        with:
+          python-version: "3.12"
+      - run: pip install ".[test]" pytest-cov
+      - run: pytest --cov=angst --cov-report=xml
+      - uses: codecov/codecov-action@v3
+        env:
+          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

README.md

@@ -1,5 +1,7 @@
 # **Angst** — Angular statistics
 
+[![codecov](https://codecov.io/gh/ntessore/angst/graph/badge.svg?token=MPIHKHSRT4)](https://codecov.io/gh/ntessore/angst)
+
 **Angst** is a _work-in-progress_ Python package for statistics on the sphere.
 
 ## Installation

src/angst/_core.py

@@ -5,6 +5,8 @@
 
 """
 
+from __future__ import annotations
+
 __all__ = [
     "inv_triangle_number",
 ]

src/angst/test/test_points.py

@@ -67,3 +67,49 @@ def test_displace_abs(rng):
     cos_a = np.cos(th) * np.cos(th_) + np.cos(delt) * np.sin(th) * np.sin(th_)
 
     npt.assert_allclose(cos_a, np.cos(abs_alpha))
+
+
+def test_displacement(rng):
+    from textwrap import dedent
+    import angst
+
+    # unit changes for displacements
+    deg5 = np.radians(5.0)
+    north = np.exp(1j * 0.0)
+    east = np.exp(1j * (np.pi / 2))
+    south = np.exp(1j * np.pi)
+    west = np.exp(1j * (3 * np.pi / 2))
+
+    # test data: coordinates and expected displacement
+    data = [
+        # equator
+        (0.0, 0.0, 0.0, 5.0, deg5 * north),
+        (0.0, 0.0, -5.0, 0.0, deg5 * east),
+        (0.0, 0.0, 0.0, -5.0, deg5 * south),
+        (0.0, 0.0, 5.0, 0.0, deg5 * west),
+        # pole
+        (0.0, 90.0, 180.0, 85.0, deg5 * north),
+        (0.0, 90.0, -90.0, 85.0, deg5 * east),
+        (0.0, 90.0, 0.0, 85.0, deg5 * south),
+        (0.0, 90.0, 90.0, 85.0, deg5 * west),
+    ]
+
+    # test each displacement individually
+    for from_lon, from_lat, to_lon, to_lat, alpha in data:
+        alpha_ = angst.displacement(from_lon, from_lat, to_lon, to_lat)
+        assert np.allclose(alpha_, alpha), dedent(
+            f"""
+            displacement from ({from_lon}, {from_lat}) to ({to_lon}, {to_lat})
+            distance: expected {np.abs(alpha)}, got {np.abs(alpha_)}
+            direction: expected {np.angle(alpha)}, got {np.angle(alpha_)}
+            """
+        )
+
+    # test on an array
+    alpha = angst.displacement(
+        rng.uniform(-180.0, 180.0, size=(20, 1)),
+        rng.uniform(-90.0, 90.0, size=(20, 1)),
+        rng.uniform(-180.0, 180.0, size=5),
+        rng.uniform(-90.0, 90.0, size=5),
+    )
+    assert alpha.shape == (20, 5)