sonar_get_coverage_gaps

Analyze code coverage gaps for a specific file. Returns uncovered code blocks optimized for LLM-assisted test generation.

Description

Identifies untested code blocks in a file, including lines with no coverage and lines with partial branch coverage. Designed to help AI assistants generate targeted test cases.

Parameters

Parameter	Type	Required	Default	Description
componentKey	string	Yes	-	SonarQube file key (e.g., project:src/file.ts)
minGapSize	number	No	1	Minimum consecutive uncovered lines
includePartialBranch	boolean	No	true	Include partial branch coverage

Finding Component Keys

Component keys follow the format: {projectKey}:{filePath}

Example: my-project-a1b2c3d4:src/services/UserService.ts

You can find them in:

• sonar_scan_project results
• sonar_get_project_metrics output
• SonarQube web UI

Usage

Basic Usage

Show me untested code in UserService.ts

Tool call:

{
  "componentKey": "my-project:src/services/UserService.ts"
}

Larger Gaps Only

Show me significant coverage gaps (5+ lines)

Tool call:

{
  "componentKey": "my-project:src/services/UserService.ts",
  "minGapSize": 5
}

Lines Only (No Branch)

Show me completely untested lines

Tool call:

{
  "componentKey": "my-project:src/services/UserService.ts",
  "includePartialBranch": false
}

Response Format

COVERAGE GAP ANALYSIS
━━━━━━━━━━━━━━━━━━━━━

File: src/services/UserService.ts
Coverage: 67.3%
Uncovered Lines: 45
Partially Covered: 12

📍 GAP 1: Lines 45-67 (Error Handling)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Coverage: 0%
Type: UNCOVERED_BLOCK

Code:
──────────────────────────────────────────────────────
  45 │ async processPayment(amount: number) {
  46 │   try {
  47 │     const result = await this.gateway.charge(amount);
  48 │     return result;
  49 │   } catch (error) {
  50 │     if (error instanceof InsufficientFundsError) {
  51 │       this.notifyUser('insufficient_funds');
  52 │       throw new PaymentError('INSUFFICIENT_FUNDS');
  53 │     }
  54 │     if (error instanceof NetworkError) {
  55 │       await this.retryQueue.add(amount);
  56 │       throw new PaymentError('NETWORK_ERROR');
  57 │     }
  58 │     throw error;
  59 │   }
  60 │ }
──────────────────────────────────────────────────────

Suggested Tests:
• Test successful payment flow
• Test InsufficientFundsError handling
• Test NetworkError with retry queue
• Test unknown error propagation

📍 GAP 2: Lines 89-102 (refund method)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Coverage: 0%
Type: UNCOVERED_BLOCK

Code:
──────────────────────────────────────────────────────
  89 │ async refund(transactionId: string) {
  90 │   const transaction = await this.findTransaction(transactionId);
  91 │   if (!transaction) {
  92 │     throw new NotFoundError('Transaction not found');
  93 │   }
  94 │   if (transaction.refunded) {
  95 │     throw new ValidationError('Already refunded');
  96 │   }
  97 │   return this.gateway.refund(transaction);
  98 │ }
──────────────────────────────────────────────────────

Suggested Tests:
• Test successful refund
• Test transaction not found
• Test already refunded error

📍 PARTIAL BRANCH: Line 34
━━━━━━━━━━━━━━━━━━━━━━━━━━

Branches Covered: 1/3
Type: PARTIAL_BRANCH

Code:
──────────────────────────────────────────────────────
  34 │ if (user.role === 'admin' || user.role === 'manager' || user.premium) {
──────────────────────────────────────────────────────

Missing Coverage:
• Branch: user.role === 'manager'
• Branch: user.premium

SUMMARY:
  3 coverage gaps found
  Estimated tests needed: 10-12
  Potential coverage increase: +25%

Gap Types

Type	Description
UNCOVERED_BLOCK	Multiple consecutive uncovered lines
UNCOVERED_LINE	Single uncovered line
PARTIAL_BRANCH	Some branches not executed

Examples

Example 1: Find Untested Error Paths

Prompt:

What error handling code isn't tested?

Tool Call:

{
  "componentKey": "my-project:src/api/handlers.ts",
  "minGapSize": 3
}

Example 2: Generate Tests for Gaps

Prompt:

Show me coverage gaps in PaymentService so I can write tests

Tool Call:

{
  "componentKey": "my-project:src/services/PaymentService.ts"
}

Example 3: Branch Coverage Focus

Prompt:

Which conditional branches aren't fully tested?

Tool Call:

{
  "componentKey": "my-project:src/utils/validators.ts",
  "includePartialBranch": true,
  "minGapSize": 1
}

Best Practices

1. Focus on critical paths - Test business logic first
2. Cover error handling - Error paths often lack tests
3. Complete branch coverage - Partial branches hide bugs
4. Use AI assistance - Let AI generate test skeletons

Common Issues

"Component not found"

Cause: Invalid component key format.

Solution: Check project key and file path match exactly.

"No coverage data"

Cause: No coverage report uploaded to SonarQube.

Solution: Configure coverage reporting in your build.

Related Tools

• sonar_get_project_metrics - Overall coverage
• sonar_scan_project - Get file keys
• sonar_get_issue_details - Related issues