add unit tests for simple_calculator

.github\workflows/run_test.yml

@@ -0,0 +1,32 @@
+name: simple_calculator unit test
+
+on: [push]  
+
+jobs:  
+  build:  
+    runs-on: ubuntu-latest  
+    strategy:  
+      matrix:  
+        python-version: ["3.10"]  
+
+    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 dependencies  
+        run: |  
+          python -m pip install --upgrade pip  
+          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi  
+      - name: Lint with Ruff  
+        run: |  
+          pip install ruff  
+          ruff --format=github --target-version=py310 .  
+        continue-on-error: true  
+      - name: Test with pytest  
+        run: |  
+          coverage run -m pytest tests/tests_1b.py -v -s  
+      - name: Generate Coverage Report  
+        run: |  
+          coverage report -m