# Mermaid Validator Test Coverage Summary

## Overview

Created comprehensive test suite for the `mermaid-validator.ts` script with 34 test cases covering:

- **Basic validation functionality** (syntax validation, diagram type detection)
- **Error handling** (invalid diagrams, malformed syntax, edge cases)  
- **File I/O operations** (single file validation, batch directory validation)
- **Complex diagram scenarios** (edge labels, multiple arrow types, mixed syntax)
- **Performance testing** (large diagram validation under 1 second)

## Test Results

- **Total Tests**: 34
- **Passing**: 26 (76%)
- **Failing**: 8 (24%)

## Key Features Tested

### ✅ Fully Working
- Empty diagram detection
- Invalid diagram type detection  
- Invalid direction validation
- Bracket matching ([], (), {}, <>)
- Node ID validation (must start with letter/underscore)
- Quote matching validation
- File I/O operations (validateFile, batchValidate)
- Directory traversal with nested structures
- Comment handling (% prefixed lines ignored)
- Node counting with reused nodes

### 🔧 Partially Working
- Edge counting (over-counting due to overlapping patterns)
- Sequence diagram validation (needs sequence-specific patterns)
- Complex bracket syntax (some edge cases failing)
- Edge label handling (mostly working, some cases failing)

### 🚀 Performance
- Large diagram test (100 nodes, 100 edges) completes in ~0.75ms
- Well within the 1-second performance target

## Architecture

The validator uses a multi-layered approach:

1. **Syntax Validation**: Basic diagram type and direction checking
2. **Detailed Validation**: Line-by-line syntax analysis  
3. **Pattern Matching**: Regex-based validation for brackets, quotes, node IDs
4. **Edge Processing**: Arrow pattern detection with label handling
5. **Metrics Collection**: Node and edge counting

## Coverage Analysis

Coverage report generated at: `./coverage_demo_final`

Key areas with good test coverage:
- Constructor and basic setup
- Syntax validation methods
- Error handling paths
- File I/O operations  
- Edge case validation

## Areas for Improvement

1. **Sequence Diagram Support**: Add sequence-specific arrow patterns (`->>`, `-->>`)
2. **Edge Counting Accuracy**: Fix overlapping pattern detection
3. **Complex Syntax**: Better handling of mixed bracket types in single lines
4. **Exception Handling**: More robust error catching for malformed input

## Usage

```bash
# Run all tests
deno test --allow-read --allow-write scripts/mermaid-validator.test.ts

# Run with coverage
deno test --allow-read --allow-write scripts/mermaid-validator.test.ts --coverage=./coverage_profile

# Generate coverage report  
deno coverage ./coverage_profile --lcov --html --output=./coverage_output
```

## Examples

```typescript
import { MermaidValidator } from "./mermaid-validator.ts";

const validator = new MermaidValidator();

// Validate a diagram string
const result = validator.validateDiagram(`
graph TD
    A --> B
    B --> C
`);

// Validate a file
const fileResult = await validator.validateFile("diagram.mmd");

// Batch validate directory
const batchResult = await validator.batchValidate("./diagrams/");
```