vald8 0.1.3

Vald8 is a minimalist, developer-first SDK for testing LLM-powered Python functions using structured JSONL datasets.

🧪 Vald8 — Lightweight Evaluation Framework for LLM Reliability

Vald8 is a minimalist, developer-first SDK for testing LLM-powered Python functions using structured JSONL datasets.

It provides a simple way to validate:

• Schema correctness
• Instruction adherence
• Reference accuracy
• Keyword / regex expectations

With optional support for LLM-as-Judge scoring.

Focus: Make LLM evaluation as easy as pytest. Nothing more. Nothing less.

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Why Vald8?

If you're building with LLMs, you need a way to verify that your AI functions:

• produce valid JSON
• follow instructions consistently
• don't regress when prompts or models change
• behave consistently across environments
• meet quality thresholds before deployment

Vald8 gives you this with:

• ✔ One decorator
• ✔ One JSONL file
• ✔ One evaluation call

No configuration. No complexity. No over-engineering.

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Install

pip install vald8

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Core Concept

You decorate any LLM function:

from vald8 import vald8

@vald8(dataset="tests.jsonl")
def generate(prompt: str) -> dict:
    ...

Vald8 loads your dataset, runs the function against each example, and scores the results.

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Running Examples

Vald8 comes with a realistic example script that demonstrates how to evaluate functions using real LLM APIs (OpenAI, Anthropic, Gemini).

Prerequisites

1. Install SDKs:

   pip install openai anthropic google-generativeai
   

2. Set API Keys:

   export OPENAI_API_KEY="your-key-here"
   export ANTHROPIC_API_KEY="your-key-here"
   export GEMINI_API_KEY="your-key-here"
   

   Alternatively, use a .env file:

   1. Copy .env.example to .env:

      cp .env.example .env
      

   2. Edit .env and add your API keys.

Run the Examples

We provide specific examples for different testing scenarios:

1. Reference (Exact Match)

python examples/example_reference_openai.py

2. Summarization (Content Check)

python examples/example_summary_openai.py

3. Extraction (Schema Validation)

python examples/example_extraction_openai.py

4. Regex (Pattern Matching)

python examples/example_regex_openai.py

5. Safety (Refusal Check)

python examples/example_safety_openai.py

6. Judge (LLM Evaluation)

python examples/example_judge_openai.py

These scripts will:

1. Load the evaluation dataset from examples/eval_dataset.jsonl.
2. Run evaluations on the respective models.
3. Output pass/fail results and success rates.

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📁 JSONL Test Dataset Example

Save as tests.jsonl:

{"id": "math1", "input": "What is 2+2?", "expected": {"reference": "4"}}
{"id": "json1", "input": "Return JSON with name and age", "expected": {"schema": {"type": "object", "properties": {"name": {"type": "string"}, "age": {"type": "number"}}, "required": ["name", "age"]}}}
{"id": "hello1", "input": "Greet politely", "expected": {"contains": ["hello", "please"]}}
{"id": "regex1", "input": "Give a date", "expected": {"regex": "\d{4}-\d{2}-\d{2}" }}

Supported expectations:

1. Reference (Exact Match)

Checks if the output matches a reference string exactly (ignoring whitespace).

"expected": {"reference": "42"}

2. Contains (Keywords)

Checks if the output contains all specified keywords (case-insensitive).

"expected": {"contains": ["hello", "world"]}

3. Regex (Pattern Matching)

Checks if the output matches a regular expression.

"expected": {"regex": "^\\d{4}-\\d{2}-\\d{2}$"}

4. Schema (JSON Validation)

Validates that the output is valid JSON and conforms to a JSON Schema.

"expected": {
  "schema": {
    "type": "object",
    "properties": {
      "name": {"type": "string"},
      "age": {"type": "integer"}
    },
    "required": ["name", "age"]
  }
}

5. Safety (Harmful Content)

Checks for harmful content using a keyword list. Can be inverted.

"expected": {"safe": true}

6. Judge (LLM-as-a-Judge)

Uses an LLM to evaluate the output based on a custom prompt. Requires judge_provider to be configured.

"expected": {
  "judge": {
    "prompt": "Is this response polite and professional?"
  }
}

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⚙️ Configuration

Vald8 supports configuration through decorator parameters and environment variables.

Decorator Parameters

@vald8(
    dataset="path/to/dataset.jsonl",       # Required: Path to JSONL dataset
    tests=["accuracy", "schema_fidelity"], # Optional: Metrics to evaluate (default: [])
    thresholds={"accuracy": 0.9},          # Optional: Pass/fail thresholds (default: 0.8)
    judge_provider="openai",               # Optional: LLM judge provider
    judge_model="gpt-5.1",                 # Optional: Judge model name
    sample_size=10,                        # Optional: Number of examples to sample
    shuffle=True,                          # Optional: Shuffle before sampling (default: False)
    cache=True,                            # Optional: Cache results (default: True)
    cache_dir=".vald8_cache",              # Optional: Cache directory
    results_dir="runs",                    # Optional: Results directory
    fail_fast=False,                       # Optional: Stop on first failure (default: False)
    timeout=60,                            # Optional: Function timeout in seconds
    save_results=True,                     # Optional: Save detailed results (default: True)
    parallel=False                         # Optional: Parallel execution (future)
)

Environment Variables

All configuration parameters can be set via environment variables with the VALD8_ prefix:

Variable	Type	Description	Default
VALD8_TESTS	List	Comma-separated metrics (e.g., "accuracy,safety")	[]
VALD8_THRESHOLD	Float	Global threshold for all metrics	0.8
VALD8_THRESHOLD_ACCURACY	Float	Threshold for accuracy metric	0.8
VALD8_THRESHOLD_SAFETY	Float	Threshold for safety metric	1.0
VALD8_SAMPLE_SIZE	Int	Number of examples to sample	All
VALD8_SHUFFLE	Bool	Shuffle examples (true/false)	false
VALD8_CACHE	Bool	Enable caching	true
VALD8_CACHE_DIR	String	Cache directory path	.vald8_cache
VALD8_RESULTS_DIR	String	Results directory path	runs
VALD8_FAIL_FAST	Bool	Stop on first failure	false
VALD8_TIMEOUT	Int	Function timeout (seconds)	60

Judge Configuration

For LLM-as-judge metrics (instruction_adherence, safety, custom_judge):

Variable	Description	Default
VALD8_JUDGE_MODEL	Judge model name	Provider-specific
VALD8_JUDGE_API_KEY	Judge API key	From provider env var
VALD8_JUDGE_BASE_URL	Custom API base URL	Provider default
VALD8_JUDGE_TIMEOUT	Judge request timeout	30
VALD8_JUDGE_MAX_RETRIES	Max retry attempts	3
VALD8_JUDGE_TEMPERATURE	Judge temperature	0.0

Provider API Keys:

• OpenAI: OPENAI_API_KEY
• Anthropic: ANTHROPIC_API_KEY
• Bedrock: AWS_ACCESS_KEY_ID

---

🧪 Decorating an LLM Function

from vald8 import vald8
import openai

@vald8(dataset="tests.jsonl")
def generate(prompt: str) -> dict:
    response = openai.chat.completions.create(
        model="gpt-4o-mini",
        messages=[{"role": "user", "content": prompt}],
        response_format={"type": "json_object"}
    )
    return {"response": response.choices[0].message.content}

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📊 Running Evaluations

results = generate.run_eval()

print("Passed:", results["passed"])
print("Success Rate:", results["summary"]["success_rate"])
print("Details saved to:", results["run_dir"])

Example output:

✔ math1
✔ json1
✖ hello1 — missing: please
✔ regex1

Overall: 3/4 passed (75%)

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🧱 Optional: LLM-as-Judge Scoring

Useful for long-form or fuzzy outputs.

@vald8(
    dataset="tests.jsonl",
    judge_provider="openai"   # or "anthropic", "local"
)
def summarize(text: str) -> str:
    return llm_summarize(text)

Most tests require no API calls.

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CI/CD Integration

- name: Run Vald8 Tests
  run: |
    python -c "
    from my_llm import generate
    assert generate.run_eval()['passed']
    "

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Results Format

Each run produces:

runs/
└── 2025-11-21_12-01-44/
    ├── results.jsonl
    ├── summary.json
    └── metadata.json

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Configuration Options

@vald8(
    dataset="tests.jsonl",
    tests=["schema", "contains", "reference"],
    thresholds={"success_rate": 0.9},
    sample_size=None,
    cache=False,
    judge_provider=None,
)

All parameters are optional.

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📁 Results Folder Structure

Vald8 automatically saves evaluation results in a session-based hierarchy:

runs/
└── 2025-11-23_a1b2c3d4/              # Session folder (date + session_id)
    ├── extract_correct/              # Function-specific results
    │   ├── results.jsonl             # Detailed test results (one per line)
    │   ├── summary.json              # Aggregated statistics
    │   ├── metadata.json             # Run configuration and info
    │   └── report.txt                # Human-readable report
    ├── extract_incorrect/
    │   └── ...
    └── judge_correct/
        └── ...

Session Grouping: All functions evaluated in the same script run share a session ID and are grouped under one master folder.

Files:

• results.jsonl: Line-delimited JSON with each test result
• summary.json: Success rate, metrics, timing stats
• metadata.json: Function name, config, timestamp
• report.txt: Formatted report with failed tests

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Contributing

PRs welcome.

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License

MIT License — free and open source.