enable pytest in github actions (#11)

.github/workflows/pytest.yaml

@@ -0,0 +1,44 @@
+name: Run tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        # python-version: [3.7, 3.8, 3.9]
+        python-version: [3.9]
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v4
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install poetry
+      uses: snok/install-poetry@v1
+      with:
+        virtualenvs-create: true
+        virtualenvs-in-project: true
+    - name: Load cached venv
+      id: cached-poetry-dependencies
+      uses: actions/cache@v3
+      with:
+        path: .venv
+        key: venv-${{ runner.os }}-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('**/poetry.lock') }}
+    # if cache doesn't exist then install deps
+    - name: Install dependencies
+      if: steps.cached-poetry-dependencies.outputs.cache-hit != 'true'
+      run: poetry install --no-interaction --no-root
+    - name: Install library
+      run: poetry install --no-interaction
+    - name: Test with pytest
+      run: |
+        source .venv/bin/activate
+        pytest
+

tests/test_doenut.py

@@ -1,7 +1,10 @@
 import pandas as pd
 import doenut
 import pytest
+import os
 
+# since pytest runs from an arbitrary location, fix that.
+os.chdir(os.path.dirname(__file__))
 df = pd.read_csv("solar_cells_1.csv")
 inputs = pd.DataFrame(
     {