Add tests for Module 3 and Module 4 notebooks

This commit adds comprehensive test coverage for Module 3 (Production
Operations & Scaling) and Module 4 (Troubleshooting & Incident Response)
notebooks, following the same pattern established for Modules 1 and 2.

Test Infrastructure:
- tests/test_notebook_execution.py:
  - Added TestModule3Notebooks class with syntax and execution tests
    for 01_ops_sanity_checks.ipynb
  - Added TestModule4Notebooks class with:
    - Syntax tests for all 6 Module 4 notebooks (00, 01, 10, 20, 30, 40)
    - Execution tests for setup/baseline notebooks (00, 01) - read-only
    - Execution tests for failure labs (10, 20, 30, 40) - with warnings
      about failure injection and secret modification

CI/CD Integration:
- .github/workflows/test-notebooks.yml:
  - Added Module 3 and Module 4 syntax tests to CI pipeline
  - All syntax tests now run automatically on PRs and pushes

Test Features:
- Respects CI_SKIP_EXECUTION environment variable (same as Module 1)
- Uses environment variables for configuration (cloud provider, region, etc.)
- Appropriate timeouts: 600s for ops checks, 900s for failure labs
- Safety warnings for failure lab execution tests
- Syntax tests always run (including in CI)
- Execution tests skip in CI when CI_SKIP_EXECUTION=true

Module 4 Test Structure:
- Syntax tests: All 6 notebooks validated for structure
- Setup/Baseline execution: Read-only validation notebooks (00, 01)
- Failure lab execution: Separate test method with warnings about
  secret modification and failure injection (10, 20, 30, 40)

This ensures all workshop notebooks are validated for syntax correctness
and can be execution-tested when infrastructure is available, maintaining
consistency with existing test patterns.

.github/workflows/test-notebooks.yml

@@ -53,6 +53,8 @@ jobs:
         run: |
           pytest tests/test_notebook_execution.py::TestModule1Notebooks::test_module1_notebook_syntax -v
           pytest tests/test_notebook_execution.py::TestModule2Notebooks::test_module2_notebook_syntax -v
+          pytest tests/test_notebook_execution.py::TestModule3Notebooks::test_module3_notebook_syntax -v
+          pytest tests/test_notebook_execution.py::TestModule4Notebooks::test_module4_notebook_syntax -v
       
       - name: Upload test artifacts
         if: always()

tests/test_notebook_execution.py

@@ -190,3 +190,94 @@ class TestModule2Notebooks(TestNotebookExecution):
         success, output = execute_notebook(notebook_path, timeout=300)
         assert success, f"Notebook execution failed:\n{output}"
 
+
+# Module 3 tests
+class TestModule3Notebooks(TestNotebookExecution):
+    """Test Module 3 notebooks."""
+    
+    @pytest.mark.parametrize("notebook", [
+        "01_ops_sanity_checks.ipynb",
+    ])
+    def test_module3_notebook_syntax(self, notebook):
+        """Test Module 3 notebook syntax."""
+        notebook_path = NOTEBOOKS_DIR / "module-3" / notebook
+        self._validate_notebook_syntax(notebook_path)
+    
+    @pytest.mark.skipif(
+        os.environ.get("CI_SKIP_EXECUTION") == "true",
+        reason="Skipping execution in CI (requires infrastructure)"
+    )
+    @pytest.mark.parametrize("notebook", [
+        "01_ops_sanity_checks.ipynb",
+    ])
+    def test_module3_notebook_execution(self, notebook):
+        """Test Module 3 notebook execution (only if infrastructure available)."""
+        notebook_path = NOTEBOOKS_DIR / "module-3" / notebook
+        # Ops sanity checks may take longer due to resource usage checks
+        success, output = execute_notebook(notebook_path, timeout=600)
+        assert success, f"Notebook execution failed:\n{output}"
+
+
+# Module 4 tests
+class TestModule4Notebooks(TestNotebookExecution):
+    """Test Module 4 notebooks."""
+    
+    @pytest.mark.parametrize("notebook", [
+        "00_setup_or_resume_environment.ipynb",
+        "01_diagnostics_baseline.ipynb",
+        "10_failure_lab_postgres.ipynb",
+        "20_failure_lab_redis.ipynb",
+        "30_failure_lab_clickhouse.ipynb",
+        "40_failure_lab_blob_storage.ipynb",
+    ])
+    def test_module4_notebook_syntax(self, notebook):
+        """Test Module 4 notebook syntax."""
+        notebook_path = NOTEBOOKS_DIR / "module-4" / notebook
+        self._validate_notebook_syntax(notebook_path)
+    
+    @pytest.mark.skipif(
+        os.environ.get("CI_SKIP_EXECUTION") == "true",
+        reason="Skipping execution in CI (requires infrastructure)"
+    )
+    @pytest.mark.parametrize("notebook", [
+        "00_setup_or_resume_environment.ipynb",
+        "01_diagnostics_baseline.ipynb",
+    ])
+    def test_module4_notebook_execution(self, notebook):
+        """
+        Test Module 4 notebook execution (only if infrastructure available).
+        
+        Tests setup and baseline notebooks which are read-only validation.
+        Failure labs are syntax-tested only to avoid modifying production environments.
+        """
+        notebook_path = NOTEBOOKS_DIR / "module-4" / notebook
+        # Setup and baseline checks may take longer due to diagnostics collection
+        success, output = execute_notebook(notebook_path, timeout=600)
+        assert success, f"Notebook execution failed:\n{output}"
+    
+    @pytest.mark.skipif(
+        os.environ.get("CI_SKIP_EXECUTION") == "true",
+        reason="Skipping execution in CI (requires infrastructure and failure injection)"
+    )
+    @pytest.mark.parametrize("notebook", [
+        "10_failure_lab_postgres.ipynb",
+        "20_failure_lab_redis.ipynb",
+        "30_failure_lab_clickhouse.ipynb",
+        "40_failure_lab_blob_storage.ipynb",
+    ])
+    def test_module4_failure_lab_execution(self, notebook):
+        """
+        Test Module 4 failure lab notebook execution (only if infrastructure available).
+        
+        WARNING: These notebooks inject failures by modifying secrets and configurations.
+        They should only be run in test environments, not production.
+        
+        These tests validate that failure injection and remediation workflows function
+        correctly. The notebooks include safety mechanisms (commented-out injection code)
+        but should still be used with caution.
+        """
+        notebook_path = NOTEBOOKS_DIR / "module-4" / notebook
+        # Failure labs may take longer due to failure injection, observation, and remediation
+        success, output = execute_notebook(notebook_path, timeout=900)  # 15 minutes
+        assert success, f"Notebook execution failed:\n{output}"
+