coverwise

Combinatorial test coverage engine via WebAssembly. Analyzes existing tests for coverage gaps, generates minimal test suites, and extends tests incrementally — no native dependencies.

Install

npm install @libraz/coverwise

Usage

Analyze existing tests

import { Coverwise } from '@libraz/coverwise';

const cw = await Coverwise.create();

const report = cw.analyzeCoverage({
  parameters: [
    { name: 'os',      values: ['Windows', 'macOS', 'Linux'] },
    { name: 'browser', values: ['Chrome', 'Firefox', 'Safari'] },
    { name: 'env',     values: ['staging', 'production'] },
  ],
  tests: myExistingTests,
});

report.coverageRatio;  // 0.72
report.uncovered;      // ["os=Linux, browser=Safari", "os=Linux, env=production", ...]

Extend with missing coverage

const result = cw.extendTests({
  parameters,
  existing: myExistingTests,
});

result.tests.length - myExistingTests.length;  // 3 tests added
result.coverage;   // 1.0
result.uncovered;  // []

Generate from scratch

import { when } from '@libraz/coverwise';

const result = cw.generate({
  parameters: [
    { name: 'os',      values: ['Windows', 'macOS', 'Linux'] },
    { name: 'browser', values: ['Chrome', 'Firefox', 'Safari'] },
    { name: 'theme',   values: ['light', 'dark'] },
  ],
  constraints: [
    when('os').eq('Windows').then(when('browser').ne('Safari')).toString(),
  ],
});

Pure TypeScript (no WASM)

import { Coverwise } from '@libraz/coverwise/pure';

const cw = await Coverwise.create(); // no WASM loading, returns immediately
const result = cw.generate({ parameters: [/* ... */] });

Browser (CDN)

<script type="module">
  import { Coverwise } from 'https://esm.sh/@libraz/coverwise';
  const cw = await Coverwise.create();
  const result = cw.generate({ parameters: [/* ... */] });
</script>

API

| Method | Description | |--------|-------------| | Coverwise.create() | Create instance (loads WASM once) | | cw.analyzeCoverage(params, tests, strength?, constraints?) | Measure t-wise coverage, list uncovered combinations (constraint-excluded tuples are removed from the universe) | | cw.extendTests(existing, input) | Add only the tests needed to close coverage gaps | | cw.generate(input) | Generate minimal covering array from scratch | | cw.estimateModel(input) | Preview model statistics |

Function-based API (init() + generate(), analyzeCoverage(), ...) is also available.

Features

• Coverage analysis — Measure any test suite's t-wise coverage and list every uncovered combination
• Incremental extension — Add only the tests needed to close coverage gaps
• Pairwise & t-wise — 2-wise through arbitrary strength
• Constraints — IF/THEN/ELSE, AND/OR/NOT, relational, IN, LIKE
• Negative testing — Auto-generate single-fault tests from invalid values
• Mixed strength — Sub-models for critical parameter groups
• Boundary values — Auto-expand integer/float ranges
• Equivalence classes — Class-level coverage tracking
• Seed tests — Build on existing tests incrementally
• Deterministic — Same input + seed = same output

Requirements

• Node.js >= 18 or modern browser with WASM support
• ESM only ("type": "module")

License

Apache License 2.0