testdata-ai 0.8.0

AI-powered test data generator for QA engineers

testdata-ai

Most test data looks like this:

email="[e-mail]"
name="John Doe"
age=30

This causes unrealistic tests and hides edge cases.

testdata-ai generates realistic, culturally diverse, and behaviorally coherent data using modern LLMs.

---

Quick start

pip install "testdata-ai[openai]"
testdata-ai generate --context ecommerce_customer --count 10

from testdata_ai import generate, generate_from_model, generate_with_relationships
from pydantic import BaseModel

# Built-in context
users = generate("ecommerce_customer", count=50)

# Your own Pydantic model — no ContextSchema needed
class Order(BaseModel):
    customer_name: str
    total: float
    status: str

orders = generate_from_model(Order, count=10)

# Multi-entity datasets with referential integrity
result = generate_with_relationships({
    "customers": {"context": "ecommerce_customer", "count": 5},
    "orders": {
        "context": "restaurant_order", "count": 20,
        "parent": "customers", "fk_field": "customer_email", "parent_pk": "email",
    },
})
# result["orders"][*]["customer_email"] is always a real customer email

Why testdata-ai?

• 13 built-in domains — e-commerce, banking, healthcare, HR, IoT, travel, and more
• 3 AI providers — OpenAI, Anthropic, or a local Ollama model (no API cost)
• pytest plugin — session-scoped fixtures with caching, named seeds, and xdist support, auto-loaded
• Pydantic / JSON Schema support — generate data directly from your existing models
• Faker hybrid mode — mark fields as faker:email / faker:iban to get format-guaranteed values while AI handles the semantic context
• Unique field constraints — add unique_fields=["email", "user_id"] to any context and those fields will never duplicate within a batch
• Multi-entity datasets — generate_with_relationships() generates customers → orders → shipments with guaranteed FK integrity and semantic coherence (child records make sense given parent records)

	Faker	testdata-ai
Realistic emails	[e-mail]	[e-mail]
Cultural diversity	Limited	Names from many cultures
Behavioral coherence	None	Age, location, and habits match
Edge-case variety	Manual	AI generates it automatically
Use your own Pydantic model	Not possible	generate_from_model(MyModel, count=10)
Format-safe critical fields	✅ Faker's domain	field_providers={"email": "faker:email"}
Unique values across records	Requires manual set tracking	unique_fields=["email", "user_id"]
Multi-entity FK datasets	Sequential, no semantic link	generate_with_relationships(graph) — child records contextually match parents

Why not just use Faker?

Faker is excellent for generating syntactically valid values (emails, UUIDs, phone numbers), but it lacks semantic coherence.

Example Faker output:

name="John Smith"
email="[e-mail]"
country="Japan"

testdata-ai generates consistent records:

name="Yuki Tanaka"
email="[e-mail]"
country="Japan"

---

Table of Contents

• Installation
• Configuration
• CLI
  • generate-related
• Python API
  • generate_with_relationships()
  • generate_from_model()
• Custom Contexts
• Faker Hybrid Mode
  • Unique Field Constraints
• Pytest Plugin
• Available Contexts
• Development Roadmap

---

Installation

pip install "testdata-ai[openai]"       # OpenAI only
pip install "testdata-ai[anthropic]"    # Anthropic only
pip install "testdata-ai[ollama]"       # Ollama only (no extra packages — uses stdlib)
pip install "testdata-ai[faker]"        # Faker hybrid mode (format-safe fields)
pip install "testdata-ai[all]"          # All providers + Faker

Development install (from source)

git clone https://github.com/testcraft-ai/testdata-ai.git
cd testdata-ai
python -m venv venv && source venv/bin/activate
pip install -e ".[all]"

---

Configuration

Create a .env file in the project root:

# Provider selection
AI_PROVIDER=openai          # openai | anthropic | ollama

# OpenAI
OPENAI_API_KEY=sk-proj-...
OPENAI_MODEL=gpt-4o-mini    # default; gpt-4o for higher quality
OPENAI_MAX_TOKENS=4096
OPENAI_TEMPERATURE=0.7

# Anthropic
ANTHROPIC_API_KEY=sk-ant-...
ANTHROPIC_MODEL=claude-haiku-4-5-20251001   # default
ANTHROPIC_MAX_TOKENS=4096
ANTHROPIC_TEMPERATURE=0.7

# Ollama (local, no API key required)
OLLAMA_BASE_URL=http://localhost:11434  # default
OLLAMA_MODEL=qwen2.5:14b               # default
OLLAMA_MAX_TOKENS=4096
OLLAMA_TEMPERATURE=0.7

# Locale (optional — applies to all providers)
AI_LOCALE=pl   # BCP 47 tag; overridden by --locale or locale= per call

All env vars are optional except *_API_KEY (Ollama requires no API key). Defaults: gpt-4o-mini / claude-haiku-4-5-20251001 / qwen2.5:14b, temperature 0.7, max_tokens 4096.

---

CLI

After installation, use the testdata-ai command (or python -m testdata_ai):

generate

Generate test data records and output as JSON, JSONL, CSV, YAML, or SQL.

testdata-ai generate --context <name> [OPTIONS]
testdata-ai generate --schema-file <path> [OPTIONS]

Option	Default	Description
--context TEXT	—	Context name (see Available Contexts). Mutually exclusive with --schema-file
--schema-file PATH	—	JSON or YAML file containing a JSON Schema definition. Mutually exclusive with --context
--count INTEGER	10	Number of records to generate
--batch-size INTEGER	10	Records per AI call. For count > batch-size, records are output progressively
-o, --output [json|jsonl|csv|yaml|sql]	json	Output format. Write to file via shell redirection: -o csv > data.csv
--table TEXT	context name	Table name for SQL output
--provider TEXT	from env	AI provider override (openai / anthropic / ollama)
--model TEXT	from env	Model name override
--max-tokens INTEGER	from env	Max tokens per AI call (auto-adjusted to batch-size by default)
--temperature FLOAT	from env	Sampling temperature 0.0–1.0
--locale TEXT	from env	Locale/language for generated values (e.g. pl, ja, de). Overrides AI_LOCALE env var
--no-validate	off	Skip schema validation
--context-file PATH	—	YAML or JSON file with custom context definitions (repeatable)
-q, --quiet	off	Suppress status messages (data only to stdout)

Examples:

# 10 e-commerce customers to stdout (JSON)
testdata-ai generate --context ecommerce_customer --count 10

# 50 SaaS trial users saved as CSV
testdata-ai generate --context saas_trial --count 50 -o csv > trials.csv

# SQL INSERT statements for direct database seeding
testdata-ai generate --context ecommerce_customer --count 100 -o sql > seed.sql

# SQL with a custom table name
testdata-ai generate --context banking_user --count 20 -o sql --table bank_accounts > accounts.sql

# 100 records in batches of 20 — JSONL lines appear after each batch
testdata-ai generate --context ecommerce_customer --count 100 --batch-size 20 -o jsonl

# Use Anthropic instead of the default provider
testdata-ai generate --context banking_user --count 5 --provider anthropic

# Use a local Ollama model
testdata-ai generate --context ecommerce_customer --count 10 --provider ollama

# Generate data in Polish
testdata-ai generate --context ecommerce_customer --count 5 --locale pl

# Generate data in Japanese, save as CSV
testdata-ai generate --context banking_user --count 10 --locale ja -o csv > data.csv

# Use a specific model with higher token budget
testdata-ai generate --context hr_employee --count 30 --model gpt-4o --max-tokens 8192

# Machine-readable output (no status messages, plain JSON)
testdata-ai generate --context iot_device --count 20 -q | jq '.[0]'

# Use as Python module (same interface)
python -m testdata_ai generate --context ecommerce_customer --count 5

# Load a custom context from a YAML file and generate data for it
testdata-ai generate --context game_character --context-file my_contexts.yaml --count 5

# Quiet: suppress all status messages including the "Loaded context(s)..." line
testdata-ai generate --context game_character --context-file my_contexts.yaml -q

# Generate from a JSON Schema file (no built-in context needed)
testdata-ai generate --schema-file product_schema.json --count 10
testdata-ai generate --schema-file order_schema.yaml --count 5 -o csv > orders.csv
testdata-ai generate --schema-file ticket_schema.json --count 20 --locale pl

Batch generation / streaming: Large counts are split into multiple AI calls of --batch-size records each. Progress is reported per batch in stderr. With -o jsonl, records are written to stdout as each batch completes — output starts immediately rather than waiting for all records. With -o yaml, each batch is appended as it arrives. With -o json, -o csv, or -o sql, all records are accumulated and written at the end.

Token auto-adjustment: When --max-tokens is not set, the CLI estimates the required token budget per batch and automatically increases it if needed, printing a yellow notice to stderr.

CSV output: Nested dicts are flattened with dot notation (e.g., location.city); lists are serialized as JSON strings.

JSONL output: One JSON object per line — records appear progressively as batches complete.

YAML output: Records are appended batch-by-batch as generation progresses.

SQL output: Emits a CREATE TABLE IF NOT EXISTS DDL statement followed by INSERT INTO statements — compatible with SQLite and most major databases. Column types are inferred per field (INTEGER, REAL, TEXT). Nested dicts are flattened with underscore separators (e.g., address_city); lists are serialized as JSON strings. The table name defaults to the context name and can be overridden with --table.

---

list-contexts

List all available contexts.

testdata-ai list-contexts [--category CATEGORY] [--context-file PATH]...

# List all contexts
testdata-ai list-contexts

# Filter by category
testdata-ai list-contexts --category finance
testdata-ai list-contexts --category healthcare

# Include custom contexts from a file
testdata-ai list-contexts --context-file my_contexts.yaml

---

show-context

Show full details of a context: fields, sample record, and prompt hints.

testdata-ai show-context <context> [--context-file PATH]...

testdata-ai show-context ecommerce_customer
testdata-ai show-context logistics_shipment

# Show a custom context defined in a file
testdata-ai show-context game_character --context-file my_contexts.yaml

---

list-models (Ollama only)

List models available in the running Ollama instance.

testdata-ai list-models [--provider ollama]

# Requires AI_PROVIDER=ollama in .env, or pass --provider explicitly
testdata-ai list-models
testdata-ai list-models --provider ollama

If no models are found, the command prints a hint to run ollama pull <model>.

---

generate-related

Generate multiple related entity datasets with guaranteed referential integrity. Unlike running generate separately for each entity, child prompts include sample parent records so the AI produces semantically coherent data — order amounts match the parent customer's income tier, shipment addresses match the order destination, etc.

testdata-ai generate-related --graph-file <path> [OPTIONS]

Option	Default	Description
--graph-file PATH	—	YAML or JSON relationship graph file (required)
-o, --output [json|jsonl-per-entity]	json	Output format
--batch-size INTEGER	10	Records per AI call (applied to all nodes unless overridden in graph)
--provider TEXT	from env	AI provider override
--model TEXT	from env	Model name override
--max-tokens INTEGER	from env	Max tokens per AI call (auto-adjusted per node by default)
--temperature FLOAT	from env	Sampling temperature
--locale TEXT	from env	Locale/language for all generated values
--no-validate	off	Skip schema validation
-q, --quiet	off	Suppress status messages (data only to stdout)

Graph file format (relationships.yaml):

customers:
  context: ecommerce_customer
  count: 5

orders:
  context: restaurant_order
  count: 20
  parent: customers        # must be generated before orders
  fk_field: customer_email # field injected into each order record
  parent_pk: email         # field taken from parent customer records
  parent_sample_size: 3    # how many parent records shown in AI prompt (default 3)
  batch_size: 10           # records per AI call for this node (default 10)

Multi-level chains work too — just reference the right parent at each level:

customers:
  context: ecommerce_customer
  count: 3

orders:
  context: restaurant_order
  count: 9
  parent: customers
  fk_field: customer_email
  parent_pk: email

shipments:
  context: logistics_shipment
  count: 9
  parent: orders
  fk_field: reference_order_id
  parent_pk: order_id

Examples:

# Generate from a graph file, output JSON
testdata-ai generate-related --graph-file examples/ecommerce_graph.yaml

# JSONL format — one line per entity, useful for streaming / jq
testdata-ai generate-related --graph-file examples/ecommerce_graph.yaml -o jsonl-per-entity

# Pipe orders to jq
testdata-ai generate-related --graph-file examples/ecommerce_graph.yaml -q \
    | jq '.orders[] | {id: .order_id, email: .customer_email}'

# Polish locale, 5-record batches
testdata-ai generate-related --graph-file examples/ecommerce_graph.yaml \
    --locale pl --batch-size 5

Output formats:

• json (default) — {"customers": [...], "orders": [...]}
• jsonl-per-entity — one line per entity: {"entity": "customers", "records": [...]}

---

Python API

DataGenerator

from testdata_ai import DataGenerator

# Default provider from .env
gen = DataGenerator()

# Explicit provider
gen = DataGenerator(provider="anthropic")

# Local Ollama model (no API key needed)
gen = DataGenerator(provider="ollama")
gen = DataGenerator(provider="ollama", model="mistral:latest")

# Full control
gen = DataGenerator(
    provider="openai",
    model="gpt-4o",
    temperature=0.9,
    max_tokens=8192,
)

# Pass API key directly (provider required when using api_key)
gen = DataGenerator(provider="openai", api_key="sk-proj-...")

# Generate data in a specific locale
gen = DataGenerator(locale="pl")   # Polish names, addresses, etc.
gen = DataGenerator(locale="ja")   # Japanese

# Generate records
customers = gen.generate("ecommerce_customer", count=10)
patients  = gen.generate("healthcare_patient", count=5)

# Large counts — automatically split into batches of 20 AI calls each
many = gen.generate("banking_user", count=100, batch_size=20)

# Skip schema validation
records = gen.generate("banking_user", count=20, validate=False)

DataGenerator.generate() returns List[Dict[str, Any]] — a list of plain Python dicts. For count > batch_size, it automatically splits the work into multiple AI calls and combines the results.

Raises:

• ValueError — unknown context, invalid JSON from AI, or bad arguments
• testdata_ai.contexts.ValidationError — one or more records missing required fields (when validate=True)

---

generate() convenience function

For one-off use without instantiating the class:

from testdata_ai import generate

customers = generate("ecommerce_customer", count=20)

# Generate in a specific locale
polish_customers = generate("ecommerce_customer", count=20, locale="pl")

# Large counts split automatically into 20-record batches
many = generate("ecommerce_customer", count=100, batch_size=20)

Configuration (provider, model, etc.) is read from environment variables. For explicit control use DataGenerator directly.

---

generate_batched() — streaming / incremental output

When you want to process or display records as they arrive rather than waiting for the full result:

from testdata_ai.generator import generate_batched

# Process records in batches of 10 as each batch completes
for batch in generate_batched("ecommerce_customer", count=50, batch_size=10):
    print(f"Got {len(batch)} records")
    save_to_db(batch)       # commit each batch immediately
    send_to_pipeline(batch) # or stream to a downstream system

# Or use DataGenerator directly for repeated use
gen = DataGenerator(provider="anthropic")
for batch in gen.generate_batched("banking_user", count=100, batch_size=20):
    process(batch)

generate_batched() / DataGenerator.generate_batched() yield List[Dict[str, Any]] — one batch per iteration.

---

generate_with_relationships() — Multi-entity datasets

Generate multiple related entity datasets in a single call. The graph is executed in dependency order (topological sort), and child prompts include sample parent records so the AI produces contextually consistent data — not just FK injection after the fact.

from testdata_ai import DataGenerator

gen = DataGenerator()

result = gen.generate_with_relationships({
    "customers": {
        "context": "ecommerce_customer",
        "count": 5,
    },
    "orders": {
        "context": "restaurant_order",
        "count": 20,
        "parent": "customers",
        "fk_field": "customer_email",   # field to inject into each order
        "parent_pk": "email",           # field from parent used as FK value
        "parent_sample_size": 3,        # parent records shown in AI prompt
        "batch_size": 10,               # records per AI call (default 10)
    },
})

# result["customers"] → List[Dict] — 5 customers
# result["orders"]    → List[Dict] — 20 orders, each with customer_email set to a real customer email

# FK integrity is always guaranteed (safety-net injection after AI generation)
customer_emails = {c["email"] for c in result["customers"]}
assert all(o["customer_email"] in customer_emails for o in result["orders"])

Three-level chain — customers → orders → shipments:

result = gen.generate_with_relationships({
    "customers": {"context": "ecommerce_customer", "count": 3},
    "orders": {
        "context": "restaurant_order", "count": 9,
        "parent": "customers", "fk_field": "customer_email", "parent_pk": "email",
    },
    "shipments": {
        "context": "logistics_shipment", "count": 9,
        "parent": "orders", "fk_field": "reference_order_id", "parent_pk": "order_id",
    },
})

Locale support:

# All entities generated in Polish
gen = DataGenerator(locale="pl")
result = gen.generate_with_relationships({...})

Module-level convenience function:

from testdata_ai import generate_with_relationships

result = generate_with_relationships(
    {
        "customers": {"context": "ecommerce_customer", "count": 2},
        "orders": {
            "context": "restaurant_order", "count": 6,
            "parent": "customers", "fk_field": "customer_email", "parent_pk": "email",
        },
    },
    validate=True,
    locale="ja",
)

Graph node fields:

Field	Required	Default	Description
context	yes	—	Registered context identifier
count	yes	—	Number of records to generate
parent	no	—	Parent node name (makes this a child node)
fk_field	when parent set	—	Field to inject into each child record
parent_pk	when parent set	—	Field from parent records used as FK value
parent_sample_size	no	3	Parent records embedded in child AI prompt
batch_size	no	10	Records per AI call for this node

Raises:

• ValueError — missing required fields, unknown parent reference, or cycle in graph
• testdata_ai.contexts.ValidationError — records missing required fields (when validate=True)

Graph YAML files — save any graph dict as YAML and use it with the CLI:

testdata-ai generate-related --graph-file relationships.yaml

See examples/ecommerce_graph.yaml and examples/relationships.py for full examples.

---

generate_from_model() — Schema from Pydantic / JSON Schema

If you already have Pydantic models, pass them directly — no need to write a ContextSchema by hand. The field names, types, descriptions, and constraints are extracted automatically and used to guide the AI.

from pydantic import BaseModel, Field
from testdata_ai import generate_from_model

class Customer(BaseModel):
    name: str
    email: str = Field(description="Valid email address")
    age: int = Field(ge=18, le=99, description="Age in years")
    is_active: bool

data = generate_from_model(Customer, count=10)
# [{"name": "Aisha Patel", "email": "aisha@...", "age": 34, "is_active": True}, ...]

Nested models work too:

class Address(BaseModel):
    street: str
    city: str
    country: str

class Order(BaseModel):
    order_id: str
    customer_name: str
    total: float
    shipping_address: Address

data = generate_from_model(Order, count=5)

Raw JSON Schema dict — no Pydantic needed:

schema = {
    "title": "Product",
    "properties": {
        "sku":      {"type": "string"},
        "name":     {"type": "string", "description": "Display name"},
        "price":    {"type": "number", "minimum": 0},
        "category": {"enum": ["electronics", "clothing", "food"]},
        "in_stock": {"type": "boolean"},
    },
}
data = generate_from_model(schema, count=5)

All the usual options apply:

# Locale
data = generate_from_model(Customer, count=5, locale="pl")

# Skip validation (useful for models with many optional fields)
data = generate_from_model(Customer, count=10, validate=False)

# Via DataGenerator (reuse across multiple models)
gen = DataGenerator(provider="anthropic")
customers = gen.generate_from_model(Customer, count=5)
orders    = gen.generate_from_model(Order, count=3)

Inspect the derived schema without calling the AI:

from testdata_ai.schema_adapter import model_to_context_schema

cs = model_to_context_schema(Customer)
print(cs.description)    # "Auto-generated from Customer schema"
print(cs.fields)         # ['name', 'email', 'age', 'is_active']
print(cs.sample)         # {'name': 'example_name', 'email': '[e-mail]', ...}
print(cs.prompt_hints)   # ['email: Valid email address', 'age: Age in years', 'age: min=18, max=99']

Supported schema features: $ref / $defs, anyOf / oneOf (null-safe), enum, const, string format (email, date, date-time, uri), numeric minimum / maximum, minLength / maxLength, nested objects and arrays, Pydantic v1 (.schema()) and v2 (.model_json_schema()). No new dependencies — Pydantic is detected by duck-typing.

---

list_contexts() / get_context_schema()

from testdata_ai import list_contexts, get_context_schema

# All context names
names = list_contexts()

# Filter by category
finance_contexts = list_contexts(category="finance")

# Inspect a schema
schema = get_context_schema("ecommerce_customer")
print(schema.fields)       # ['name', 'email', 'age', ...]
print(schema.description)  # 'e-commerce customer profiles'
print(schema.category)     # 'ecommerce'
print(schema.sample)       # full sample dict
print(schema.prompt_hints) # list of generation hints

---

Sample output

{
  "name": "Aisha Patel",
  "email": "[e-mail]",
  "age": 28,
  "location": {
    "city": "Mumbai",
    "country": "India",
    "timezone": "Asia/Kolkata"
  },
  "shopping_behavior": {
    "frequency": "weekly",
    "avg_order_value": "$45-80",
    "preferred_categories": ["electronics", "books"],
    "device": "mobile",
    "payment_method": "upi"
  },
  "joined_date": "2023-04-15",
  "loyalty_tier": "silver"
}

---

Custom Contexts

The 13 built-in contexts cover common domains, but you can define your own for any data shape your project needs.

File-based (YAML or JSON)

Create a YAML file where each top-level key is a context name:

# my_contexts.yaml
game_character:
  description: "RPG game character profiles"
  category: "gaming"
  sample:
    character_id: "CHAR-0042"
    name: "Theron Blackwood"
    class: "Ranger"
    level: 15
    gold: 340
  prompt_hints:
    - "Fantasy names from diverse real-world cultures"
    - "Classes: Warrior, Mage, Ranger, Rogue, Cleric, Paladin, Druid, Bard"
    - "Level range 1-20; gold 10-5000 depending on level"

Load it with --context-file on any CLI command:

testdata-ai generate --context game_character --context-file my_contexts.yaml --count 5
testdata-ai list-contexts --context-file my_contexts.yaml
testdata-ai show-context game_character --context-file my_contexts.yaml

The flag is repeatable — pass multiple files to load several context collections at once.

JSON files are also supported (same structure, .json extension).

Programmatic (register_context)

Register contexts at runtime from Python — useful in conftest.py or application setup:

from testdata_ai import register_context, ContextSchema

# Using ContextSchema
register_context("game_npc", ContextSchema(
    description="RPG non-player character profiles",
    category="gaming",
    sample={
        "npc_id": "NPC-0011",
        "name": "Mira Dawnwhisper",
        "role": "innkeeper",
        "disposition": "friendly",
        "gold": 80,
    },
    prompt_hints=[
        "Fantasy names from diverse real-world cultures",
        "Roles: innkeeper, blacksmith, guard, merchant, quest-giver",
        "Gold: 10-500 depending on role",
    ],
))

# Using a plain dict (no import of ContextSchema needed)
register_context("game_item", {
    "description": "RPG inventory items",
    "category": "gaming",
    "sample": {"item_id": "ITM-099", "name": "Elven Cloak", "rarity": "rare", "value_gold": 250},
    "prompt_hints": ["Rarities: common, uncommon, rare, epic, legendary"],
})

Both approaches register the context globally for the current process — DataGenerator and the pytest plugin pick it up immediately.

Loading from Python

from testdata_ai import load_contexts_from_file

names = load_contexts_from_file("my_contexts.yaml")  # returns ['game_character']

Schema rules

Field	Required	Notes
description	yes	Non-empty string
sample	yes	Non-empty dict; keys become the required field names
prompt_hints	yes	List of strings (empty list is allowed but reduces output quality)
category	no	Defaults to "custom"
field_providers	no	Dict mapping field name → "faker:method_name". Requires pip install testdata-ai[faker]
unique_fields	no	List of field names (must be a subset of field_providers keys) that will be unique within a batch

Name rules: context names must start with a letter or underscore and contain only letters, digits, and underscores (snake_case recommended).

Warnings: register_context and load_contexts_from_file emit a UserWarning when prompt_hints is empty or when the sample contains nested dicts/lists (nested types are not validated at runtime).

Overwriting: pass overwrite=True to replace an existing context (including built-ins). A warning is emitted when a built-in is shadowed.

Atomicity: if a file contains multiple contexts and one fails validation, none of them are registered.

---

Faker Hybrid Mode

AI excels at semantic coherence — names, locations, and behaviors that feel like real people. Faker excels at format correctness — emails that pass regex checks, IBANs with valid checksums, UUIDs that are actually valid.

Faker hybrid mode combines both: AI generates the full record, then Faker overwrites specific fields with guaranteed-valid values.

pip install "testdata-ai[faker]"

Add field_providers to any ContextSchema:

from testdata_ai import register_context, ContextSchema, DataGenerator

register_context("banking_pl", ContextSchema(
    description="Polish retail banking customer",
    sample={
        "name": "Jan Kowalski",
        "email": "[e-mail]",
        "iban": "PL61109010140000071219812874",
        "phone": "[phone]",
        "balance": 4250.00,
    },
    prompt_hints=["Realistic Polish names", "Balance 500–50000 PLN"],
    field_providers={
        "email": "faker:email",
        "iban":  "faker:iban",
        "phone": "faker:phone_number",
    },
))

gen = DataGenerator(locale="pl_PL")
records = gen.generate("banking_pl", count=10)
# → AI generates name + balance (semantically coherent)
# → Faker generates email + iban + phone (format guaranteed)

Works with generate_from_model too:

from testdata_ai import generate_from_model

data = generate_from_model(
    Customer,
    count=10,
    field_providers={"email": "faker:email", "phone": "faker:phone_number"},
)

How it works:

1. AI generates the complete record (all fields, semantically coherent)
2. Faker overwrites only the listed fields with format-guaranteed values
3. Schema validation runs on the final combined record

Faker locale follows DataGenerator.locale — DataGenerator(locale="pl_PL") gives Polish phone numbers and emails automatically.

Common providers:

Spec	Example output
faker:email	[e-mail]
faker:phone_number	[phone]
faker:iban	PL61 1090 1014 0000 0712 1981 2874
faker:uuid4	550e8400-e29b-41d4-a716-446655440000
faker:url	https://example.com/path
faker:ipv4	192.168.1.42
faker:date	2024-03-15
faker:postcode	00-001
faker:company	Kowalski & Synowie Sp. z o.o.

Full list: faker.readthedocs.io → Providers

---

Unique Field Constraints

unique_fields works with any field backed by a Faker method — emails, UUIDs, usernames, phone numbers, IBANs, IP addresses, and more. Add it to any ContextSchema to guarantee no duplicates within a generated batch:

register_context("saas_user", ContextSchema(
    description="SaaS trial user",
    sample={
        "name": "Alice Chen",
        "email": "[e-mail]",
        "company": "Acme Inc",
        "plan": "trial",
    },
    prompt_hints=["Diverse professional names", "Plans: trial / starter / pro / enterprise"],
    field_providers={
        "email": "faker:email",
    },
    unique_fields=["email"],   # no duplicate emails in the batch
))

gen = DataGenerator()
records = gen.generate("saas_user", count=100)
emails = [r["email"] for r in records]
assert len(emails) == len(set(emails))  # always passes

Multiple unique fields at once:

register_context("order", ContextSchema(
    ...,
    field_providers={
        "order_id": "faker:uuid4",
        "customer_email": "faker:email",
    },
    unique_fields=["order_id", "customer_email"],
))

Works with generate_from_model too:

records = generate_from_model(
    UserSchema,
    count=50,
    field_providers={"user_id": "faker:uuid4", "email": "faker:email"},
    unique_fields=["user_id", "email"],
)

And in YAML context files:

employee_unique:
  description: "HR employee with unique email"
  sample:
    name: "Fatima Al-Rashid"
    email: "[e-mail]"
    department: "Engineering"
    salary: 125000
  prompt_hints:
    - "Diverse names from different cultures"
    - "Salary 50k–250k depending on seniority"
  field_providers:
    email: "faker:email"
  unique_fields:
    - email

Rules:

• unique_fields must be a subset of field_providers keys — validated at schema construction time with a clear error
• Works with any Faker method that has sufficient cardinality: faker:email, faker:uuid4, faker:user_name, faker:phone_number, faker:iban, faker:ipv4, faker:company, etc.
• Avoid low-cardinality methods (e.g. faker:boolean has only 2 values) — Faker raises UniquenessException if it exhausts all possible distinct values
• Uniqueness is guaranteed within a single generate() call (one batch). Across multiple generate_batched() iterations, each batch is internally unique but values can repeat between batches

---

Pytest Plugin

The plugin ships with the package and is auto-loaded via the pytest11 entry point — no import or conftest setup needed.

Marker fixture: testdata

Function-scoped. Use with @pytest.mark.testdata to generate any context at any count. count defaults to 1 if omitted.

import pytest

@pytest.mark.testdata(context="ecommerce_customer", count=5)
def test_checkout_flow(testdata):
    assert len(testdata) == 5
    assert all("email" in row for row in testdata)

@pytest.mark.testdata(context="banking_user", count=1)
def test_single_bank_user(testdata):
    user = testdata[0]
    assert 300 <= user["credit_score"] <= 850

# Generate data in a specific locale
@pytest.mark.testdata(context="ecommerce_customer", count=3, locale="pl")
def test_polish_customers(testdata):
    assert len(testdata) == 3

Auto-generated context fixtures

For every context, the plugin auto-generates two session-scoped fixtures:

Fixture name	Returns	Example
<context>	Single dict (1 record)	ecommerce_customer
<context>s	List of 10 dicts	ecommerce_customers

def test_single(ecommerce_customer):
    assert "email" in ecommerce_customer

def test_list(ecommerce_customers):
    assert len(ecommerce_customers) == 10

def test_patient(healthcare_patient):
    assert "blood_type" in healthcare_patient

def test_employees(hr_employees):
    assert all("salary" in e for e in hr_employees)

Caching and seeds

The plugin caches AI responses to avoid redundant API calls within and across test runs. Cache files live in .testdata_ai_cache/. Add .testdata_ai_cache/ and .testdata_ai.log to your .gitignore.

Seed = a named cache snapshot. Use --testdata-seed to name and reuse a cache:

# First run: generate data and save under "smoke-seed"
pytest --testdata-seed smoke-seed

# Subsequent runs: reuse the cached data (no AI calls)
pytest --testdata-seed smoke-seed

# Reuse the most recently used named seed
pytest --testdata-last-seed

Without --testdata-seed, a temporary seed is created per run and deleted automatically when the session ends.

Seed and cache management

These options perform an admin action and exit without running tests:

# List all available seeds
pytest --testdata-list-seeds

# Show what's cached in the current (or a specific) seed
pytest --testdata-show-cache
pytest --testdata-show-cache smoke-seed

# Delete a specific seed
pytest --testdata-delete-seed smoke-seed

# Delete the last used seed
pytest --testdata-delete-last

# Clear all seeds and reset the last-seeds queue
pytest --testdata-clear-cache

pytest-xdist support

When running with pytest-xdist, each worker will make its own AI calls unless you specify a shared named seed:

# Recommended: share one cache across all workers
pytest -n 4 --testdata-seed my-seed

Without --testdata-seed, a warning is printed per worker.

Manual fixture pattern

If you prefer explicit control in conftest.py:

# conftest.py
import pytest
from testdata_ai import DataGenerator

@pytest.fixture(scope="session")
def test_customers():
    gen = DataGenerator()
    return gen.generate("ecommerce_customer", count=10)

# test_checkout.py
def test_checkout_flow(test_customers):
    customer = test_customers[0]
    assert customer["email"]
    assert customer["age"] >= 18

Logging

The plugin writes structured logs to .testdata_ai.log (rotating, max 5 MB × 3 backups) and to stderr. Log entries include seed name and xdist worker ID.

---

Available Contexts

Context	Category	Key Fields
ecommerce_customer	ecommerce	name, email, age, location, shopping_behavior, joined_date, loyalty_tier
banking_user	finance	name, email, age, account_type, balance, monthly_income, credit_score, branch, account_opened
saas_trial	saas	name, email, company, role, plan, signup_date, trial_expires, usage_stats
healthcare_patient	healthcare	patient_id, name, date_of_birth, gender, blood_type, primary_diagnosis, medications, allergies, insurance_provider, last_visit, attending_physician
education_student	education	student_id, name, email, age, major, minor, year, gpa, enrollment_status, courses, advisor
b2b_lead	b2b	lead_id, contact_name, email, phone, company, industry, company_size, job_title, lead_source, lead_score, deal_value, stage, notes
hr_employee	hr	employee_id, name, email, department, job_title, hire_date, salary, employment_type, manager, location, performance_rating
real_estate_listing	real_estate	listing_id, address, property_type, bedrooms, bathrooms, sqft, year_built, list_price, status, days_on_market, agent, features
iot_device	iot	device_id, device_type, manufacturer, firmware_version, location, status, battery_level, last_reading, alert_threshold, installed_date
social_media_profile	social_media	username, display_name, bio, followers, following, posts, verified, joined, category, engagement_rate, top_hashtags
travel_booking	travel	booking_id, passenger_name, email, trip_type, origin, destination, departure_date, return_date, cabin_class, total_price, currency, travelers, status, add_ons
restaurant_order	food	order_id, customer_name, restaurant, cuisine, items, subtotal, delivery_fee, tip, total, payment_method, order_type, status, ordered_at
logistics_shipment	logistics	tracking_number, carrier, origin, destination, ship_date, estimated_delivery, actual_delivery, weight_kg, dimensions_cm, contents, status, last_checkpoint

Run testdata-ai list-contexts to see all contexts, or testdata-ai show-context <name> for full field details and a sample record.

---

Development Roadmap

Done:

• OpenAI + Anthropic + Ollama provider-agnostic architecture
• 13 built-in contexts across 13 categories
• Schema validation with missing-field reporting
• CLI (generate, list-contexts, show-context, list-models) with JSON, JSONL, CSV, YAML, and SQL output
• Auto token estimation and adjustment
• Spinner with elapsed time (animated on TTY, static on non-TTY)
• python -m testdata_ai support
• Pytest plugin: marker fixture, auto-context fixtures, seed/cache system
• Seed cache management CLI options (list, show, delete, clear)
• TEMP seed auto-cleanup after session
• pytest-xdist support with shared named seeds
• Rotating log file (.testdata_ai.log)
• Batch generation / streaming — generate_batched(), --batch-size, progressive JSONL/YAML output
• Custom contexts — register_context(), load_contexts_from_file(), --context-file CLI option
• PyPI publish — pip install testdata-ai · py.typed marker for fully typed public API
• Locale / language support — --locale pl / DataGenerator(locale="ja") / AI_LOCALE env var; pytest plugin marker support
• Schema-from-model — generate_from_model(MyPydanticModel) / generate_from_model(json_schema_dict) / --schema-file CLI option
• Faker hybrid mode — field_providers={"email": "faker:email"} in ContextSchema; optional testdata-ai[faker] extra; locale-aware
• Unique field constraints — unique_fields=["email", "user_id"] in ContextSchema; uses Faker's uniqueness proxy; per-batch guarantee
• SQL output format — -o sql with CREATE TABLE IF NOT EXISTS + INSERT INTO; type inference; --table override
• Relationship generation — generate_with_relationships() / generate-related CLI; graph YAML files; semantic coherence (parent records in child prompt); guaranteed FK integrity; topological sort; batch generation

Next:

• /docs folder — installation, quickstart, CLI reference, API reference, custom contexts, pytest integration
• Async API — async def generate() / generate_batched() for high-throughput pipelines
• pandas output — DataGenerator.to_dataframe() convenience method
• More providers — Google Gemini, Mistral, Cohere

---

Contributing

Contributions welcome — see CONTRIBUTING.md for the full guide. See CHANGELOG.md for version history.

• Found a bug? Open a bug report
• Have an idea? Open a feature request
• Want to code? Fork, branch, and open a PR

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Related

• qa-ai-prompts — 100+ battle-tested AI prompts for QA engineers. Copy, paste, customize — get results in seconds.

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License

MIT License — see LICENSE

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Built by TestCraft AI