Testing tools

LesliTesting configures a set of tools around standard Minitest. The project still owns its test cases, assertions, fixtures, and Rails test environment.

Minitest reporter

The custom reporter replaces the default Minitest reporter and prints:

• A status line for each test unless quiet mode is enabled
• PASS, SKIP, FAIL, or ERROR labels
• Test class and method names
• Assertion counts
• Execution time for tests taking more than one second
• Totals for tests, passes, failures, errors, skips, assertions, success rate, and duration
• Formatted locations and assertion details for failures

Assertion counts are color-coded to make tests with very few assertions easy to spot. This is guidance in the terminal output; it does not change whether a test passes.

Set QUIET=true to suppress per-test lines while keeping the final summary and failure information:

QUIET=true bundle exec rake

Coverage

Coverage is disabled during ordinary test runs. Set COVERAGE to true, 1, or yes to start SimpleCov:

COVERAGE=true bundle exec rake

When coverage is enabled, requiring lesli_testing starts Ruby's line coverage before the LesliTesting implementation, Rails, or the project under test is loaded. The subsequent LesliTesting.app, LesliTesting.engine, or LesliTesting.gem call applies the selected SimpleCov profile, formatters, and minimum threshold.

Every coverage run produces:

The minimum line-coverage threshold defaults to 90 percent. Configure it for a suite with coverage_min_coverage:

LesliTesting.gem(
  "MyGem",
  coverage_min_coverage: 85
)

The coverage process exits unsuccessfully when the result is below the configured threshold.

Use coverage_missing_len to limit the length of missing-line details in the console formatter:

LesliTesting.engine(
  "MyEngine",
  coverage_missing_len: 40
)

Set it to 0 to remove the limit.

Environment variables

Values are case-insensitive and surrounding whitespace is ignored. Only true, 1, and yes enable these options. Unset variables and values such as false, 0, and no leave them disabled.

COVERAGE is evaluated when lesli_testing is required, so it must be set before the Ruby process starts. QUIET changes reporter output only; it does not change assertions, summaries, coverage, or exit codes.

Process exit codes

Other boot, dependency, signal, or operating-system failures may use other non-zero codes. See Load order and process behavior for the complete lifecycle.

Shared Rails test classes

The shared classes are registered through ActiveSupport load hooks. They are created when rails/test_help loads their corresponding Rails classes, regardless of whether LesliTesting was configured before or after the Rails application booted. Engine suites should still run through bundle exec rails test or bundle exec rake app:test.

IntegrationTester

LesliTesting::IntegrationTester inherits from ActionDispatch::IntegrationTest and includes response helpers:

class AccountsControllerTest < LesliTesting::IntegrationTester
  test "returns JSON" do
    get accounts_url, as: :json

    assert_successful_json_response
    assert_kind_of Array, response_json
  end
end

Available helpers:

ModelTester

LesliTesting::ModelTester inherits from ActiveSupport::TestCase and includes ActiveSupport::Testing::TimeHelpers:

class SubscriptionTest < LesliTesting::ModelTester
  test "expires tomorrow" do
    travel_to Time.zone.local(2026, 9, 26, 12) do
      assert_equal Date.new(2026, 9, 27), Subscription.expires_tomorrow
    end
  end
end

ViewTester

LesliTesting::ViewTester inherits from ActionView::TestCase. When available, subclasses receive Lesli::HtmlHelper and Lesli::SystemHelper:

class NavigationHelperTest < LesliTesting::ViewTester
  test "renders navigation" do
    assert_includes render_navigation, "Dashboard"
  end
end

Engine fixtures and migrations

For the engine profile, LesliTesting waits for Rails to load and then resolves the owner from the name passed to LesliTesting.engine. With a conventional engine layout it automatically registers:

• the owner's test/fixtures and test/fixtures/files directories;
• shared fixtures from Lesli;
• the dummy application's, owner engine's, and shared Lesli migration directories;
• all fixtures on ActiveSupport::TestCase and their paths on integration tests.

The migration Railtie runs only when Rails.env.test?. The engine name is the default target; use engine: when the reporter name and engine constant differ:

LesliTesting.engine("My engine tests", engine: "MyEngine")

Lesli is always the shared base for Rails application and engine profiles. Additional values passed through shared: are appended without removing it. LesliTesting maps these fixture sets to their namespaced models:

Fixture paths and classes are applied through Rails load hooks. Migration paths are added during the dummy application's test boot and again when Active Record becomes available; both operations preserve and de-duplicate existing paths. This allows coverage to start before Rails without losing test data configuration.

Custom owners, paths, shared engines, fixture sets, model mappings, and migration paths can be supplied through the fixtures: and migrations: options. See Testing Rails engines for the complete configuration.