Ruby Best Practices

Testing and Code Coverage

• Write tests for all new code. No code changes should be accepted without corresponding test coverage. Prefer writing tests first using Test Driven Development (TDD).
• Mock all external API calls in tests. Never allow tests to make real network requests.
• Improve coverage when modifying existing code, especially for files with low coverage (e.g., data_fetcher.rb, github_client.rb, html_generator.rb).
• Always run the coverage report (bundle exec rake coverage) to verify the impact of your changes.
• Place test files in the test/ directory, use a _test.rb suffix, and require test_helper at the top.
• Follow the test_method_name pattern for test methods.
• Use Mocha’s mock and stubs for external dependencies.
• Use setup and teardown for test preparation and cleanup.
• Store fixtures in test/fixtures/.
• Add an empty line before each assertion method to comply with RuboCop’s Minitest/EmptyLineBeforeAssertionMethods rule and improve readability.
• Limit test methods to no more than 5 assertions. Split tests as needed and ensure each has independent setup.

Method Design and Complexity

• Each method should have a single, clear responsibility. If a method’s purpose requires “and” to describe, split it.
• Keep methods under 20 lines (excluding comments). Cyclomatic complexity should be under 7; perceived complexity under 8. Extract helper methods as needed.
• Use descriptive method names. Break lines longer than 100 characters using line continuation with \.
• Use guard clauses and early returns for edge cases.
• Extract validation, data transformation, and complex conditionals into dedicated, well-named helper methods.
• Always test newly extracted methods. If helpers are private, consider testable delegation in test environments.

Ruby Style and RuboCop Compliance

• Use 2 spaces for indentation, never tabs.
• Keep lines under 100 characters.
• Use spaces around operators, after commas, colons, and semicolons. No trailing whitespace at line ends or on blank lines.
• End each file with a newline.
• Use snake_case for variables, methods, and file names; CamelCase for classes/modules; SCREAMING_SNAKE_CASE for constants.
• Use single quotes for non-interpolated strings, double quotes for interpolated or special-character strings.
• Add # frozen_string_literal: true at the top of every file.
• Prefer early returns for error and edge cases.
• Use visibility modifiers (private, protected) to encapsulate implementation details.
• Group related methods together within classes/modules.
• Add comments for complex or non-obvious code. Document public methods, parameters, and return values.
• Rescue only specific exceptions, not Exception or bare rescue. Use descriptive messages for exceptions and log them appropriately.

Common RuboCop Offenses and Fixes

• Watch for and remove trailing whitespace, especially on blank

Sources