ci: add GitHub Actions workflow for tests

- Run tests on Python 3.9, 3.10, 3.11, 3.12
- Run ruff linter
- Run coverage report
- Test stdlib-only mode (without requests)
- Add badges to README

Author: amargiovanni

.github/workflows/tests.yml

@@ -0,0 +1,68 @@
+name: Tests
+
+on:
+  push:
+    branches: [main, 001-modular-refactor]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.9', '3.10', '3.11', '3.12']
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements-dev.txt
+          pip install -r requirements.txt
+
+      - name: Run linter
+        run: |
+          ruff check src/github_analyzer/
+
+      - name: Run tests
+        run: |
+          pytest tests/ -v --tb=short
+
+      - name: Run tests with coverage
+        run: |
+          pytest tests/ --cov=src/github_analyzer --cov-report=xml --cov-report=term-missing
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v4
+        if: matrix.python-version == '3.11'
+        with:
+          files: ./coverage.xml
+          fail_ci_if_error: false
+
+  test-stdlib-only:
+    name: Test without requests (stdlib only)
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python 3.11
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install test dependencies only
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest pytest-cov
+
+      - name: Run tests without requests
+        run: |
+          pytest tests/ -v --tb=short

README.md

@@ -1,5 +1,9 @@
 # GitHub Analyzer
 
+[![Tests](https://github.com/Oltrematica/github_analyzer/actions/workflows/tests.yml/badge.svg)](https://github.com/Oltrematica/github_analyzer/actions/workflows/tests.yml)
+[![Python 3.9+](https://img.shields.io/badge/python-3.9+-blue.svg)](https://www.python.org/downloads/)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 A powerful Python command-line tool for analyzing GitHub repositories and extracting comprehensive metrics about commits, pull requests, issues, and contributor activity. Generate detailed CSV reports for productivity analysis and code quality assessment.
 
 ![GitHub Analyzer Banner](screens/screen1.png)