test: Add test for environment validation error during initialization

Author: Yoshihiro Takahara

tests/test_text_editor.py

@@ -889,3 +889,20 @@ def mock_open(*args, **kwargs):
     assert "Failed to write file" in result["reason"]
     assert test_file.read_text() == "original content\n"  # File should be unchanged
     editor._validate_environment()
+
+
+@pytest.mark.asyncio
+async def test_initialization_with_environment_error(monkeypatch):
+    """Test TextEditor initialization when environment validation fails."""
+    
+    def mock_validate_environment(self):
+        raise EnvironmentError("Failed to validate environment")
+    
+    # Patch the _validate_environment method
+    monkeypatch.setattr(TextEditor, "_validate_environment", mock_validate_environment)
+    
+    # Verify that initialization fails with the expected error
+    with pytest.raises(EnvironmentError) as excinfo:
+        TextEditor()
+    
+    assert "Failed to validate environment" in str(excinfo.value)