Litmux

Unit tests for AI. Test prompts, compare models, catch regressions.

pip install litmux && litmux init && litmux run

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Why

Every team shipping AI features hits the same three problems:

1. No testing standard. REST has Postman, frontends have Cypress. LLM calls have manual spot-checking.
2. Prompt regression is invisible. A one-word change can silently break 15% of edge cases.
3. Model selection is vibes. "We use GPT-4o because it's good" — but is it $15k/month better than Gemini Flash?

Litmux gives you a YAML config, pass/fail assertions, and a cost report. That's it.

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Quick Start

pip install litmux
cp .env.example .env
Add at least one: OPENAI_API_KEY, ANTHROPIC_API_KEY, GOOGLE_API_KEY, HF_TOKEN
litmux init    # scaffold a project
litmux run     # run tests against all configured models

No database, no cloud account, no Docker.

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Core Commands

litmux run — unit tests for prompts

# litmux.yaml
models:
  - model: gpt-4o-mini
  - model: claude-haiku-4-5-20251001
tests:

name: summarize_earnings
prompt: prompts/summarize.txt
inputs:
text: "Revenue grew 15% to $4.2 billion..."
assert:

type: contains
value: "revenue"
type: cost-less-than
value: 0.01

litmux eval — bulk evaluation against datasets

evals:
  - name: ticket_classifier
    prompt: prompts/classify.txt
    dataset: datasets/support_tickets.csv
    input_mapping:
      ticket: text
    expected: expected_category
    assert:
      - type: json-valid
    judge:
      criteria: "Did the model correctly classify the ticket?"
      threshold: 7.0

litmux generate — AI-generated test datasets

litmux generate \
  --prompt prompts/classify.txt \
  --seed datasets/sample_tickets.csv \
  --n 50 \
  --output datasets/support_tickets.csv

litmux cost — cost projection across models

litmux cost --volume 50000

Finds the cheapest model that passes your tests.

litmux compare — side-by-side model outputs

litmux compare

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Cloud (Optional, Free)

Sync results to a hosted dashboard for history, trends, and team visibility.

litmux login       # one-time browser auth
litmux run         # results auto-sync
litmux dashboard   # open app.litmux.dev

The CLI works fully offline. Cloud is opt-in.

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Assertion Types

Type	Description
contains	Output contains substring
not-contains	Output does not contain substring
regex	Output matches regex pattern
json-valid	Output is valid JSON
json-schema	Output has required JSON keys
cost-less-than	Cost below threshold (USD)
latency-less-than	Latency below threshold (ms)
llm-judge	LLM scores output 1–10 against criteria

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CI/CD

# .github/workflows/litmux.yml
- run: litmux run --ci
  env:
    OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}

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Configuration

models:
  - provider: openai | anthropic | google | huggingface
    model: string
    temperature: 0.0
    max_tokens: 1024
defaultTest:
assert:
- type: cost-less-than
value: 0.01
tests:

name: string
prompt: path/to/prompt.txt
inputs: { variable: "value" }
assert:

type: contains
value: "expected"



evals:

name: string
prompt: path/to/prompt.txt
dataset: path/to/data.csv
input_mapping: { prompt_var: csv_column }
expected: csv_column
assert: [...]
judge:
criteria: "..."
threshold: 7.0

Environment Variables

Variable	Purpose
OPENAI_API_KEY	OpenAI models, LLM judge, dataset generation
ANTHROPIC_API_KEY	Anthropic models
GOOGLE_API_KEY	Google models
HF_TOKEN	HuggingFace models
LITMUX_NO_CACHE	Set to 1 to skip the response cache
LITMUX_API_URL	Override cloud API endpoint (default: https://api.litmux.dev)
LITMUX_API_URL_ALLOW_INSECURE	Set to 1 to allow non-HTTPS LITMUX_API_URL (local dev only)
LITMUX_DASHBOARD_URL	Override dashboard URL (default: https://app.litmux.dev)
LITMUX_JUDGE_MODEL	LLM model used for llm-judge assertions (default: gpt-4o-mini)
LITMUX_CLOUD_ENABLED	Set to 1 to opt in to Litmux Cloud (private beta)

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All Commands

litmux run                    Run all tests
litmux run -t <name>          Run a specific test
litmux run --ci               CI output (markdown)
litmux eval                   Run all evals
litmux eval --limit 10        Evaluate first N rows
litmux generate ...           Generate a test dataset
litmux compare                Side-by-side model outputs
litmux cost -v 50000          Project monthly cost
litmux cache                  View / clear response cache
litmux init                   Scaffold a new project
litmux version                Show version
Cloud (private beta — join the waitlist at https://litmux.dev)
litmux login                  Authenticate with Litmux Cloud
litmux logout                 Remove saved credentials
litmux history                Recent runs from cloud
litmux dashboard              Open the dashboard

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Examples

See examples/ for three ready-to-run projects:

• 01-quickstart — minimal single-model test
• 02-multi-model — compare across providers
• 03-generate-and-eval — AI-generated dataset + LLM judge

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License

MIT