Declarative fixture blueprints
Defines repeatable records through compact field rules instead of copying or manually editing production-shaped examples.
Day 039 / APIs / Test Data
Mock API Fixture Builder
/ Overview
A dependency-free Python CLI that turns a bounded JSON blueprint into deterministic synthetic API fixtures in JSON array or JSON Lines format.
Frontend work, demos and automated tests often need predictable API-shaped records. Copying production data creates privacy risk, while hand-editing fixtures is repetitive and can leave examples inconsistent between runs.
/ Provided servicesClear thinking.
Clear thinking.
Practical delivery.
Strict input boundaries
Rejects unknown keys, unsupported rule types, invalid field names and oversized record or field counts.
Two practical formats
Writes an indented JSON array for review or one compact object per line for streaming-oriented tools.
/ Solution
Mock API Fixture Builder validates a small declarative JSON blueprint and creates deterministic synthetic records using integer sequences, numbered strings, alternating booleans, cycling enums and null fields. It enforces record, field and rule boundaries, outputs JSON or JSON Lines, and never connects to an API.
/ Impact
Deterministic synthetic records
Five focused field-rule types
One to 1,000 bounded records
One to 50 validated fields
JSON array and JSON Lines output
Twelve standard-library tests included
Python standard library
Argparse, pathlib, regular expressions and JSON provide the complete dependency-free command-line workflow.
Synthetic test data
Generates integer, string, boolean, enum and null values deterministically from a local blueprint.
Unittest
Twelve tests cover every rule, deterministic ordering, input limits, unknown configuration and CLI output.