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Testing CLI Server Command Execution and Docker Bootstrap in Kamal

This test suite validates server-side CLI commands and Docker bootstrapping functionality in Kamal, focusing on command execution and Docker installation scenarios across multiple hosts.

Test Coverage Overview

The test suite provides comprehensive coverage of server-side command execution and Docker bootstrapping processes.

Command execution testing across multiple hosts
Docker installation verification
Root vs non-root user scenarios
Multi-host command propagation

Implementation Analysis

The testing approach employs Minitest with extensive use of stubs and mocks to simulate server responses and command execution.

SSHKit backend mocking for remote command simulation
Command output validation using assertions
Systematic host iteration testing
Error handling verification

Technical Details

Framework: Minitest
Testing Tools: SSHKit for remote execution
Mocking Library: Built-in Minitest stubs
Test Environment: CLI command simulation
Configuration: YAML-based test fixtures

Best Practices Demonstrated

The test suite exemplifies robust testing practices for CLI applications, particularly in distributed environments.

Comprehensive error case coverage
Isolated test scenarios
Clear test case organization
Effective use of test fixtures
Thorough command output validation

basecamp/kamal

test/cli/server_test.rb

            
require_relative "cli_test_case"

class CliServerTest < CliTestCase
  test "running a command with exec" do
    SSHKit::Backend::Abstract.any_instance.stubs(:capture)
      .with("date", verbosity: 1)
      .returns("Today")

    hosts = "1.1.1.1".."1.1.1.4"
    run_command("exec", "date").tap do |output|
      hosts.map do |host|
        assert_match "Running 'date' on #{hosts.to_a.join(', ')}...", output
        assert_match "App Host: #{host}\nToday", output
      end
    end
  end

  test "running a command with exec multiple arguments" do
    SSHKit::Backend::Abstract.any_instance.stubs(:capture)
      .with("date -j", verbosity: 1)
      .returns("Today")

    hosts = "1.1.1.1".."1.1.1.4"
    run_command("exec", "date", "-j").tap do |output|
      hosts.map do |host|
        assert_match "Running 'date -j' on #{hosts.to_a.join(', ')}...", output
        assert_match "App Host: #{host}\nToday", output
      end
    end
  end

  test "bootstrap already installed" do
    stub_setup
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:docker, "-v", raise_on_non_zero_exit: false).returns(true).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:mkdir, "-p", ".kamal").returns("").at_least_once

    assert_equal "Acquiring the deploy lock...\nReleasing the deploy lock...", run_command("bootstrap")
  end

  test "bootstrap install as non-root user" do
    stub_setup
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:docker, "-v", raise_on_non_zero_exit: false).returns(false).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with('[ "${EUID:-$(id -u)}" -eq 0 ] || command -v sudo >/dev/null || command -v su >/dev/null', raise_on_non_zero_exit: false).returns(false).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:mkdir, "-p", ".kamal").returns("").at_least_once

    assert_raise RuntimeError, "Docker is not installed on 1.1.1.1, 1.1.1.3, 1.1.1.4, 1.1.1.2 and can't be automatically installed without having root access and the `curl` command available. Install Docker manually: https://docs.docker.com/engine/install/" do
      run_command("bootstrap")
    end
  end

  test "bootstrap install as root user" do
    stub_setup
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:docker, "-v", raise_on_non_zero_exit: false).returns(false).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with('[ "${EUID:-$(id -u)}" -eq 0 ] || command -v sudo >/dev/null || command -v su >/dev/null', raise_on_non_zero_exit: false).returns(true).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:sh, "-c", "'curl -fsSL https://get.docker.com || wget -O - https://get.docker.com || echo \"exit 1\"'", "|", :sh).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(:mkdir, "-p", ".kamal").returns("").at_least_once
    Kamal::Commands::Hook.any_instance.stubs(:hook_exists?).returns(true)
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(".kamal/hooks/pre-connect", anything).at_least_once
    SSHKit::Backend::Abstract.any_instance.expects(:execute).with(".kamal/hooks/docker-setup", anything).at_least_once

    run_command("bootstrap").tap do |output|
      ("1.1.1.1".."1.1.1.4").map do |host|
        assert_match "Missing Docker on #{host}. Installing…", output
        assert_match "Running the docker-setup hook", output
      end
    end
  end

  private
    def run_command(*command)
      stdouted { Kamal::Cli::Server.start([ *command, "-c", "test/fixtures/deploy_with_accessories.yml" ]) }
    end
end