Overrides

Published 0.5.0 uses non-empty attributes objects with string, finite number, boolean, or null values. Matching is exact and type-sensitive; strings, numbers, and booleans are not coerced. Set context-specific overrides that take precedence over percentage rollout and the global flag value:

// Enable for a specific tenant
await this.flags.setOverride('MY_FLAG', {
  attributes: { tenantId: 'tenant-1' },
  enabled: true,
});

// Disable for a specific user
await this.flags.setOverride('MY_FLAG', {
  attributes: { userId: 'user-42' },
  enabled: false,
});

// Enable only in staging
await this.flags.setOverride('MY_FLAG', {
  attributes: { environment: 'staging' },
  enabled: true,
});

// Combine dimensions
await this.flags.setOverride('MY_FLAG', {
  attributes: {
    tenantId: 'tenant-1',
    userId: 'user-42',
    environment: 'production',
  },
  enabled: true,
  priority: 10,
});

Top-level explicit userId, tenantId, and environment are merged into the resolved attributes and take precedence over same-named nested attributes. Explicit tenant IDs work without the optional tenancy package. If multiple overrides match, the evaluator selects more attributes, higher priority, earlier createdAt, then lower id. See rollout precedence.

Remove an Override v0.2.0

await this.flags.removeOverride('MY_FLAG', {
  attributes: { tenantId: 'tenant-1' },
});

The operation is idempotent — removing a non-existent override does not throw.

Find a Flag by Key v0.2.0

const flag = await this.flags.findByKey('MY_FLAG');
// Returns the full flag with overrides, or throws NotFoundException

Testing

Import TestFeatureFlagModule from the /testing subpath to stub flag values in tests without a database connection:

import { INestApplication } from '@nestjs/common';
import { Test } from '@nestjs/testing';
import request from 'supertest';
import { TestFeatureFlagModule } from '@nestarc/feature-flag/testing';
import { DashboardController } from './dashboard.controller';

// DashboardController is the guarded controller from the installation guide.
describe('DashboardController', () => {
  let app: INestApplication;

  beforeEach(async () => {
    const module = await Test.createTestingModule({
      imports: [
        TestFeatureFlagModule.register({
          NEW_DASHBOARD: true,
          PREMIUM_FEATURE: false,
        }),
      ],
      controllers: [DashboardController],
    }).compile();

    app = module.createNestApplication();
    await app.init();
  });

  afterEach(() => app.close());

  it('should allow access when flag is enabled', () => {
    return request(app.getHttpServer())
      .get('/dashboard')
      .expect(200);
  });
});

TestFeatureFlagModule.register() provides a global mock of FeatureFlagService where isEnabled(key) returns the boolean you specified (defaulting to false for unregistered keys) and evaluateAll() returns the full map.

The test module is a service stub: it does not run real override matching, rollout hashing, persistence, or events. Use the real service in an integration test to verify those behaviors.