Implement a simple test

Author: DanShort12

.github/workflows/python.yml

@@ -23,9 +23,12 @@ jobs:
     - name: Install plasma source
       run: |
         git submodule update --init --recursive
-        pip install wheel
+        pip install -r requirements-develop.txt
         python setup.py bdist_wheel
         python -m pip install --verbose dist/*.whl
+    - name: run tests
+      run: |
+        pytest tests
     - name: upload wheel
       uses: actions/upload-artifact@v2
       with:

requirements-develop.txt

@@ -0,0 +1,2 @@
+pytest
+wheel

tests/test_plasma_source.py

@@ -0,0 +1,40 @@
+"""Tests for the methods in plasma_source."""
+
+import pytest
+
+from parametric_plasma_source.plasma_source import PlasmaSource
+
+plasma_params = {
+    "elongation": 1.557,
+    "ion_density_origin": 1.09e20,
+    "ion_density_peaking_factor": 1,
+    "ion_density_pedistal": 1.09e20,
+    "ion_density_seperatrix": 3e19,
+    "ion_temperature_origin": 45.9,
+    "ion_temperature_peaking_factor": 8.06,
+    "ion_temperature_pedistal": 6.09,
+    "ion_temperature_seperatrix": 0.1,
+    "major_radius": 906.0,
+    "minor_radius": 292.258,
+    "pedistal_radius": 0.8 * 292.258,
+    "plasma_id": 1,
+    "shafranov_shift": 44.789,
+    "triangularity": 0.270,
+    "ion_temperature_beta": 6,
+}
+
+
+@pytest.fixture(scope="session")
+def plasma_source():
+    """Make a plasma source to use as a test fixture."""
+    return PlasmaSource(**plasma_params)
+
+
+class TestPlasmaSource:
+    """A class to run tests against the plasma source."""
+
+    def test_ion_density_magnetic_origin(self, plasma_source):
+        """Test the ion density at the magnetic origin."""
+        ion_density = plasma_source.ion_density(0.0)
+
+        assert pytest.approx(ion_density, 1.09e20)