The role of slicing in test-driven development

TL;DR

This paper introduces a theoretical framework for TDD emphasizing the importance of slicing, contracts, and their interrelations, supported by an industry-controlled experiment to explore TDD's foundational mechanisms.

Contribution

It proposes a novel theoretical model linking TDD, slicing, and contracts, and empirically investigates these connections through a controlled industry experiment.

Findings

TDD cycles correspond to vertical slices of user stories.

Contracts serve as implicit slicing criteria in TDD.

Code during TDD acts as a sliced specification using contracts.

Abstract

Test-driven development (TDD) is a widely used agile practice. However, very little is known with certainty about TDD's underlying foundations, i.e., the way TDD works. In this paper, we propose a theoretical framework for TDD, with the following characteristics: 1) Each TDD cycle represents a vertical slice of a (probably also small) user story, 2) vertical slices are captured using contracts, implicit in the developers' minds, and 3) the code created during a TDD cycle is a sliced-based specification of a code oracle, using the contracts as slicing pre/post-conditions. We have checked the connections among TDD, contracts, and slices using a controlled experiment conducted in the industry.