Back to Repositories

Testing SMTP Data Command Implementation in Postal Server

This test suite validates SMTP server client data handling in the Postal server project, focusing on email data processing, header management, and content validation. The tests ensure proper SMTP command sequencing and message construction.

Test Coverage Overview

The test suite provides comprehensive coverage of SMTP DATA command handling:

Command sequence validation (HELO, MAIL FROM, RCPT TO)
Error handling for missing prerequisites
Header processing and validation
Message content construction
Received header generation

Implementation Analysis

The testing approach uses RSpec’s behavior-driven development patterns to validate SMTP client functionality. It employs context-specific test cases with detailed setup and assertions to verify email processing behavior.

Uses RSpec describe and context blocks for organized test structure
Leverages let statements for test data setup
Implements before blocks for test state preparation

Technical Details

Testing infrastructure includes:

RSpec testing framework
Factory patterns for test data generation
Timecop for time-dependent testing
Mock SMTP client implementation
Custom matchers for SMTP response validation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolation of test cases
Proper setup and teardown procedures
Clear test case descriptions
Comprehensive error case coverage
Effective use of test doubles and factories

postalserver/postal

spec/lib/smtp_server/client/data_spec.rb

            
# frozen_string_literal: true

require "rails_helper"

module SMTPServer

  describe Client do
    let(:ip_address) { "1.2.3.4" }
    subject(:client) { described_class.new(ip_address) }

    describe "DATA" do
      it "returns an error if no helo" do
        expect(client.handle("DATA")).to eq "503 HELO/EHLO, MAIL FROM and RCPT TO before sending data"
      end

      it "returns an error if no mail from" do
        client.handle("HELO test.example.com")
        expect(client.handle("DATA")).to eq "503 HELO/EHLO, MAIL FROM and RCPT TO before sending data"
      end

      it "returns an error if no rcpt to" do
        client.handle("HELO test.example.com")
        client.handle("MAIL FROM: [email protected]")
        expect(client.handle("DATA")).to eq "503 HELO/EHLO, MAIL FROM and RCPT TO before sending data"
      end

      it "returns go ahead" do
        route = create(:route)
        client.handle("HELO test.example.com")
        client.handle("MAIL FROM: [email protected]")
        client.handle("RCPT TO: #{route.name}@#{route.domain.name}")
        expect(client.handle("DATA")).to eq "354 Go ahead"
      end

      it "adds a received header for itself" do
        route = create(:route)
        client.handle("HELO test.example.com")
        client.handle("MAIL FROM: [email protected]")
        client.handle("RCPT TO: #{route.name}@#{route.domain.name}")
        Timecop.freeze do
          client.handle("DATA")
          expect(client.headers["received"]).to include "from test.example.com (1.2.3.4 [1.2.3.4]) by #{Postal::Config.postal.smtp_hostname} with SMTP; #{Time.now.utc.rfc2822}"
        end
      end

      describe "subsequent commands" do
        let(:route) { create(:route) }
        before do
          client.handle("HELO test.example.com")
          client.handle("MAIL FROM: [email protected]")
          client.handle("RCPT TO: #{route.name}@#{route.domain.name}")
        end

        it "logs headers" do
          client.handle("DATA")
          client.handle("Subject: Test")
          client.handle("From: [email protected]")
          client.handle("To: [email protected]")
          client.handle("To: [email protected]")
          client.handle("X-Something: abcdef1234")
          client.handle("X-Multiline: 1234")
          client.handle("             4567")
          expect(client.headers["subject"]).to eq ["Test"]
          expect(client.headers["from"]).to eq ["[email protected]"]
          expect(client.headers["to"]).to eq ["[email protected]", "[email protected]"]
          expect(client.headers["x-something"]).to eq ["abcdef1234"]
          expect(client.headers["x-multiline"]).to eq ["1234             4567"]
        end

        it "logs content" do
          Timecop.freeze do
            client.handle("DATA")
            client.handle("Subject: Test")
            client.handle("")
            client.handle("This is some content for the message.")
            client.handle("It will keep going.")
            expect(client.instance_variable_get("@data")).to eq <<~DATA
              Received: from test.example.com (1.2.3.4 [1.2.3.4]) by #{Postal::Config.postal.smtp_hostname} with SMTP; #{Time.now.utc.rfc2822}\r
              Subject: Test\r
              \r
              This is some content for the message.\r
              It will keep going.\r
            DATA
          end
        end
      end
    end
  end

end