Rspec Service Testing

RSpec Service Testing Specialist

Specialized in writing comprehensive specs for service objects and business logic.

When to Use This Skill

• Testing service object business logic
• Testing multi-step workflows
• Testing transaction behavior and rollbacks
• Testing error handling in services
• Testing Result object patterns
• Creating service specs before implementation (TDD)

Core Principles

• Test First: Write service specs before implementing logic
• Comprehensive: Test success, failure, and edge cases
• Isolation: Mock external dependencies
• Transaction Testing: Verify rollback behavior
• Result Objects: Test structured return values

Service Spec Structure

# spec/services/order_processing_service_spec.rb
require 'rails_helper'

RSpec.describe OrderProcessingService do
    describe '#call' do
        let(:order) { create(:order) }
        let(:service) { described_class.new(order) }

        context 'with valid order' do
            # Success scenarios
        end

        context 'with invalid order' do
            # Failure scenarios
        end

        context 'when external service fails' do
            # Error handling tests
        end
    end
end

Testing Service Success

describe '#call' do
    let(:user) { create(:user) }
    let(:order) { create(:order, user: user) }
    let(:service) { described_class.new(order) }

    context 'with valid order' do
        before do
            create_list(:order_item, 2, order: order)
        end

        it 'returns success result' do
            result = service.call

            expect(result).to be_success
            expect(result.data).to eq(order)
        end

        it 'updates order status' do
            expect {
                service.call
            }.to change { order.reload.status }.from('pending').to('confirmed')
        end

        it 'charges payment' do
            expect(PaymentGateway).to receive(:charge).with(order)
            service.call
        end

        it 'updates inventory' do
            product = order.products.first
            expect {
                service.call
            }.to change { product.reload.stock }.by(-1)
        end

        it 'sends confirmation email' do
            expect {
                service.call
            }.to have_enqueued_job(OrderConfirmationJob).with(order.id)
        end

        it 'creates transaction log' do
            expect {
                service.call
            }.to change(TransactionLog, :count).by(1)
        end
    end
end

Testing Service Failure

context 'with invalid order' do
    let(:order) { create(:order, :empty) }

    it 'returns failure result' do
        result = service.call

        expect(result).to be_failure
        expect(result.error).to be_present
    end

    it 'does not change order status' do
        expect {
            service.call
        }.not_to change { order.reload.status }
    end

    it 'does not charge payment' do
        expect(PaymentGateway).not_to receive(:charge)
        service.call
    end

    it 'returns descriptive error message' do
        result = service.call

        expect(result.error).to include('Order must have items')
    end
end

Testing Error Handling

context 'when payment fails' do
    before do
        create_list(:order_item, 2, order: order)
        allow(PaymentGateway).to receive(:charge).and_raise(PaymentError, 'Insufficient funds')
    end

    it 'returns failure result' do
        result = service.call

        expect(result).to be_failure
        expect(result.error_type).to eq(:payment_failed)
    end

    it 'logs error' do
        expect(Rails.logger).to receive(:error).with(/PaymentError/)
        service.call
    end

    it 'does not update order status' do
        expect {
            service.call
        }.not_to change { order.reload.status }
    end
end

Testing Transaction Rollback

describe 'transaction rollback' do
    before do
        create_list(:order_item, 2, order: order)
        allow(PaymentGateway).to receive(:charge).and_raise(PaymentError)
    end

    it 'rolls back all changes on error' do
        initial_status = order.status
        initial_stock = order.products.first.stock

        service.call

        expect(order.reload.status).to eq(initial_status)
        expect(order.products.first.reload.stock).to eq(initial_stock)
    end

    it 'does not create transaction log on rollback' do
        expect {
            service.call
        }.not_to change(TransactionLog, :count)
    end
end

Testing Service with Options

describe 'service options' do
    it 'uses custom payment method' do
        service = described_class.new(order, payment_method: 'credit_card')

        expect(PaymentGateway).to receive(:charge).with(order, method: 'credit_card')
        service.call
    end

    it 'skips email when skip_email option is true' do
        service = described_class.new(order, skip_email: true)

        expect {
            service.call
        }.not_to have_enqueued_job(OrderConfirmationJob)
    end
end

Testing Multiple Scenarios

describe 'payment processing' do
    context 'when amount is under limit' do
        let(:order) { create(:order, total: 100) }

        it 'processes without additional verification' do
            expect(PaymentGateway).not_to receive(:verify)
            service.call
        end
    end

    context 'when amount exceeds limit' do
        let(:order) { create(:order, total: 10000) }

        it 'requires additional verification' do
            expect(PaymentGateway).to receive(:verify).with(order)
            service.call
        end
    end
end

Testing Form Objects

# spec/forms/user_registration_form_spec.rb
RSpec.describe UserRegistrationForm do
    describe '#save' do
        let(:valid_params) do
            {
                email: 'test@example.com',
                password: 'password123',
                password_confirmation: 'password123',
                terms_accepted: '1'
            }
        end

        let(:form) { described_class.new(valid_params) }

        context 'with valid parameters' do
            it 'creates a user' do
                expect {
                    form.save
                }.to change(User, :count).by(1)
            end

            it 'creates user profile' do
                expect {
                    form.save
                }.to change(UserProfile, :count).by(1)
            end

            it 'sends welcome email' do
                expect {
                    form.save
                }.to have_enqueued_job(WelcomeEmailJob)
            end

            it 'returns created user' do
                user = form.save
                expect(user).to be_a(User)
                expect(user).to be_persisted
            end
        end

        context 'with invalid parameters' do
            let(:invalid_form) { described_class.new(email: 'invalid') }

            it 'does not create user' do
                expect {
                    invalid_form.save
                }.not_to change(User, :count)
            end

            it 'returns false' do
                expect(invalid_form.save).to be false
            end

            it 'adds validation errors' do
                invalid_form.save
                expect(invalid_form.errors[:email]).to be_present
            end
        end
    end

    describe 'validations' do
        it { should validate_presence_of(:email) }
        it { should validate_presence_of(:password) }
        it { should validate_acceptance_of(:terms_accepted) }
    end
end

Tools to Use

• Write: Create service spec files
• Edit: Update service specs
• Bash: Run service specs
• Read: Read service implementation

Bash Commands

# Run all service specs
bundle exec rspec spec/services

# Run specific service spec
bundle exec rspec spec/services/order_processing_service_spec.rb

Workflow

1. Understand Business Logic: Clarify service requirements
2. Write Failing Tests: Create specs for all scenarios
3. Run Tests: Confirm tests fail
4. Commit Tests: Commit test code
5. Implementation: Use rails-service-objects skill
6. Verify: Run tests and ensure they pass

Related Skills

• rails-service-objects: For service implementation
• rails-transactions: For transaction logic
• rails-error-handling: For error handling
• rspec-model-testing: For testing underlying models

RSpec Fundamentals

See RSpec Testing Fundamentals

FactoryBot Guide

See FactoryBot Guide

TDD Workflow

Follow TDD Workflow

Key Reminders

• Test both success and failure paths
• Test transaction rollback behavior
• Mock external dependencies (payment, email, APIs)
• Test Result object structure
• Verify side effects (emails, logs, updates)
• Test edge cases and error conditions
• Keep tests independent
• Use descriptive context names