# Test Assertion Density Calculator MCP for AI Agents MCP

> Test Assertion Density Calculator finds hollow JavaScript and TypeScript tests. It calculates the ratio of assertions to test blocks so you can spot empty scaffolding that inflates your coverage metrics without actually verifying any logic.

## Overview
- **Category:** developer-tools
- **Price:** Free
- **Endpoint:** https://edge.vinkius.com/undefined/mcp
- **Tags:** javascript, typescript, testing, metrics, coverage

## Description

The Test Assertion Density Calculator identifies empty or ineffective test scaffolding in your JavaScript and TypeScript suites. You have likely seen coverage reports that look perfect, yet your actual tests are just a collection of empty blocks that provide no real protection. This tool changes how you audit your code by measuring the density of real assertions within your test files. Instead of relying on line coverage alone, you can see exactly where your testing is shallow. You can pull this into your workflow via Vinkius to instantly spot where you have empty blocks or where your metrics are falling below industry standards. It turns a manual, tedious code review process into an automated check that ensures every test block is actually doing work.

## Tools

### assess_density_health
Evaluates the overall quality of a test file by comparing its density against industry standards. It helps you identify if your testing strength is dropping.

### calculate_test_metrics
Counts the number of tests and assertions to find the exact density ratio in a file. This provides a clear metric for test effectiveness.

### find_empty_tests
Scans your code to pinpoint the specific lines where tests exist without any assertions. It isolates ineffective code segments instantly.

## Prompt Examples

**Prompt:** 
```
Check this file for any tests that don't have assertions.
```

**Response:** 
```
I scanned the file and found one empty test at line 14 in `auth_service.test.ts`.
```

**Prompt:** 
```
What is the assertion density in my user controller test?
```

**Response:** 
```
The ratio is **0.5**. This means you have two test blocks but only one assertion recorded.
```

**Prompt:** 
```
Is my current test suite healthy based on industry standards?
```

**Response:** 
```
Your density is **1.2**, which falls within the standard range for TypeScript suites.
```

## Capabilities

### Spot hollow tests
Finds specific segments of code that represent ineffective, assertion-less tests.

### Audit test quality
Compares your current density against industry standards to check for low-quality files.

### Quantify test strength
Calculates the exact ratio of assertions to test blocks within a specific file.

## Use Cases

### Cleaning up legacy suites
A developer finds a massive TypeScript file with high coverage but zero real tests and uses the MCP to find the gaps.

### PR verification
An engineer asks their agent to check if a new PR introduces empty test blocks before merging code.

### Refactoring safety
After a major refactor, you verify that your assertion density hasn't dropped across the entire suite.

## Benefits

- Identify empty scaffolding using find_empty_tests to see where tests lack assertions.
- Verify test strength by using calculate_test_metrics to see the real ratio of assertions per block.
- Benchmark your suite with assess_density_health to compare density against industry standards.
- Reduce false confidence in coverage reports that show high execution but low validation.
- Automate code audits by letting your agent scan directories for low-density files.

## How It Works

The bottom line is you stop trusting hollow coverage numbers.

1. Connect your preferred AI client to the MCP through Vinkius.
2. Point your agent toward a JavaScript or TypeScript test file.
3. Receive a detailed breakdown of assertion density and any empty test locations.

## Frequently Asked Questions

**How can I find empty tests in my JavaScript project with Test Assertion Density Calculator?**
The tool scans your files and points to specific lines where assertions are missing. This helps you clean up hollow test blocks instantly.

**Can Test Assertion Density Calculator help with TypeScript coverage?**
Yes, it is specifically designed to analyze density in JavaScript and TypeScript suites to ensure real validation is happening.

**Does Test Assertion Density Calculator work with existing coverage reports?**
It provides a different metric than standard coverage. It looks at the ratio of assertions to blocks rather than just line execution.

**How do I know if my test density is too low using Test Assertion Density Calculator?**
You can use the health assessment feature to compare your current metrics against established industry standards.

**Can I use Test Assertion Density Calculator to automate PR reviews?**
Yes, you can ask your agent to scan new files for empty tests as part of your automated review process.

**How does the tool identify empty tests?**
The tool uses deterministic regex to find test blocks (`it`, `test`, `dscribe`) and checks if they contain any assertion keywords like `expect`, `assert`, or `should`.

**What is a good assertion density?**
A density of 2.0 or higher is considered robust, while anything below 0.5 indicates a high probability of ineffective test structures.

**Can I use this with Vitest or Jest?**
Yes, as long as your test files use standard keywords like `it`, `test`, `expect`, or `assert`, the tool will accurately calculate metrics.