ci(tests): add tests on windows + mac (not just windows)

Author: amyheather

.github/workflows/tests.yaml

@@ -1,13 +1,41 @@
+# This file runs the tests in `tests/` with every push to GitHub
+# They will run in parallel, and run on three operating systems:
+# Ubuntu, Windows and Mac.
+
 name: tests
 
 on:
   push:
   workflow_dispatch:
 
 jobs:
-  build-tests:
+
+  # Run tests on Ubuntu
+  tests-on-ubuntu:
     runs-on: ubuntu-latest
     steps:
+
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Install python and dependencies
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+      - run: pip install -r requirements.txt
+
+      - name: Run tests
+        run: pytest
+
+      - name: List the environment variables
+        run: env
+
+  # Run tests on Windows
+  tests-on-windows:
+    runs-on: windows-latest
+    steps:
+
       - name: Check out repository
         uses: actions/checkout@v4
 
@@ -19,4 +47,28 @@ jobs:
       - run: pip install -r requirements.txt
 
       - name: Run tests
-        run: pytest
+        run: pytest
+
+      - name: List the environment variables
+        run: env
+
+  # Run tests on Mac
+  tests-on-macos:
+    runs-on: macos-latest
+    steps:
+
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Install python and dependencies
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+      - run: pip install -r requirements.txt
+
+      - name: Run tests
+        run: pytest
+
+      - name: List the environment variables
+        run: env