chore: import upstream snapshot with attribution

examples/eval-python-assert/README.md

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+# eval-python-assert (Python Assertions)
+
+Example configurations for testing LLM outputs using Python assertions with promptfoo.
+
+You can run this example with:
+
+```bash
+npx promptfoo@latest init --example eval-python-assert
+cd eval-python-assert
+```
+
+## Purpose
+
+This example demonstrates how to use Python assertions for custom output validation with:
+
+- External Python files with assertion functions
+- Inline Python code directly in configuration files
+- Configuration-based assertions with custom parameters
+- Different assertion return formats (boolean, score, detailed results)
+
+## Prerequisites
+
+- Python 3.7+ installed and available in your PATH
+- OpenAI API key (or other LLM provider)
+
+## Environment Variables
+
+- `OPENAI_API_KEY` - Your OpenAI API key (required)
+
+## Configurations
+
+This example includes two different approaches:
+
+### External Python Files (`promptfooconfig-external.yaml`)
+
+Uses external Python files for complex assertion logic:
+
+- `promptfooconfig-external.yaml` - Configuration with external Python assertions
+- `assert.py` - Basic assertion function with detailed scoring
+- `assert_with_config.py` - Configuration-based assertion function
+
+### Inline Python Code (`promptfooconfig-inline.yaml`)
+
+Demonstrates inline Python assertions directly in the configuration:
+
+- `promptfooconfig-inline.yaml` - Configuration with inline Python code
+- Shows simple boolean checks and complex scoring logic
+
+## Running the Examples
+
+1. **External Python assertions example:**
+
+   ```sh
+   promptfoo eval -c promptfooconfig-external.yaml
+   ```
+
+2. **Inline Python assertions example:**
+
+   ```sh
+   promptfoo eval -c promptfooconfig-inline.yaml
+   ```
+
+3. **View results:**
+
+   ```sh
+   promptfoo view
+   ```
+
+## Python Assertion Patterns
+
+### Basic Boolean Return
+
+```python
+def get_assert(output, context):
+    return "expected_word" in output.lower()
+```
+
+### Score-Based Return
+
+```python
+def get_assert(output, context):
+    if "perfect" in output.lower():
+        return 1.0
+    elif "good" in output.lower():
+        return 0.5
+    else:
+        return 0.0
+```
+
+### Detailed Result Object
+
+```python
+def get_assert(output, context):
+    return {
+        "pass": True,
+        "score": 0.8,
+        "reason": "Contains expected content",
+        "namedScores": {"quality": 0.9, "relevance": 0.7}
+    }
+```
+
+## Expected Results
+
+- **External example**: Shows advanced assertion patterns with detailed scoring and configuration support
+- **Inline example**: Demonstrates quick assertions and simple validation logic
+
+## Learn More
+
+- [Python Assertions Documentation](https://www.promptfoo.dev/docs/configuration/expected-outputs/python/)
+- [promptfoo Configuration Guide](https://www.promptfoo.dev/docs/configuration/guide/)
+- [Assertion Types](https://www.promptfoo.dev/docs/configuration/expected-outputs/)