# Supabase pgTAP Database Testing Guide

> Comprehensive tutorial on implementing robust database testing in Supabase using the pgTAP framework for PostgreSQL unit testing.

This in-depth guide covers database testing strategies using pgTAP within Supabase projects, including practical examples, best practices, and CI/CD integration for reliable PostgreSQL database testing.

## Article Content

### Core Testing Concepts
- **pgTAP Framework**: PostgreSQL unit testing framework explanation and benefits
- **Database-Level Testing**: Why testing at the database layer is crucial for data integrity
- **Supabase Integration**: How to implement pgTAP testing within Supabase projects

### Practical Testing Examples

#### Function Testing
Testing user creation functions with input validation, verifying function existence and return values, and error handling for edge cases.

```sql
-- Example: Testing a user creation function
BEGIN;
SELECT plan(3);

-- Test function exists
SELECT has_function('create_user', ARRAY['text', 'text', 'text']);

-- Test function returns expected result
SELECT results_eq(
  'SELECT create_user(''john@example.com'', ''John'', ''Doe'')',
  'SELECT 1',
  'create_user should return 1 on success'
);

-- Test function handles invalid input
SELECT throws_ok(
  'SELECT create_user('''', ''John'', ''Doe'')',
  'Invalid email address',
  'create_user should throw error for empty email'
);

SELECT * FROM finish();
ROLLBACK;
```

#### Table Structure Testing
Validating table schemas, column definitions, primary key and unique constraints, and proper table relationships.

```sql
-- Example: Testing table structure and constraints
BEGIN;
SELECT plan(6);

-- Test table exists
SELECT has_table('users');

-- Test required columns exist
SELECT has_column('users', 'id');
SELECT has_column('users', 'email');
SELECT has_column('users', 'created_at');

-- Test if the table has a primary key constraint
SELECT has_pk('users');

-- Test unique constraint on email
SELECT has_unique('users', ARRAY['email']);

SELECT * FROM finish();
ROLLBACK;
```

#### Trigger Testing
Testing database triggers and their functions, validating automated timestamp updates and trigger behavior.

```sql
-- Example: Testing triggers
BEGIN;
SELECT plan(2);

-- Test trigger exists
SELECT trigger_is('users', 'update_updated_at', 'users', 'update_updated_at()');

-- Test trigger function
SELECT has_function('update_updated_at');

SELECT * FROM finish();
ROLLBACK;
```

### Testing Best Practices
- **Test Isolation**: Using transactions to maintain clean test environments
- **Test Organization**: Structuring tests for maintainability and readability
- **Naming Conventions**: Clear, descriptive test naming patterns
- **Coverage Strategy**: Comprehensive testing of database functionality
- **Performance Considerations**: Efficient test execution and resource usage

## CI/CD Integration

### GitHub Actions Workflow
Complete example of automated database testing using Supabase CLI in GitHub Actions, including test execution and deployment strategies.

```yaml
# .github/workflows/test-database.yml
name: Database Tests and Production Deployment

on:
  push:
    branches:
      - main
  workflow_dispatch:

jobs:
  test:
    name: Run Database Tests
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: supabase/setup-cli@v1
        with:
          version: latest
      - run: supabase db start
      - run: supabase test db
```

### Troubleshooting
- Common permission issues and solutions
- Transaction management in test environments
- Debugging test failures and false positives

## Target Audience

- **Database Developers**: Working with PostgreSQL and Supabase
- **QA Engineers**: Implementing database testing strategies
- **DevOps Teams**: Setting up automated testing pipelines
- **Full-Stack Developers**: Ensuring database reliability in applications

## Key Benefits

- **Data Integrity**: Catch database issues before production
- **Regression Prevention**: Automated detection of breaking changes
- **Documentation**: Tests serve as living documentation of database behavior
- **Confidence**: Deploy database changes with greater assurance

## Related Resources

- [Official pgTAP Documentation](https://pgtap.org/): Complete framework reference
- [HeapSoft Main Site](https://heapsoft.ch): Our database and Supabase expertise
- [Supabase MCP Server Guide](https://heapsoft.ch/blog/supabase-mcp-server): Related Supabase tooling
- [Type-Safe Database Schemas](https://heapsoft.ch/blog/building-type-safe-database-schemas): Complementary database best practices