请问TLD TWD TFD 三者是什么意思

[Changefish]

看一篇论文 摘要是描述：
Researchers have typically studied the effects of Test-First Development
(TFD), compared to Test-Last Development (TLD), across groups or projects, and
for relatively short durations. We defined Test-With Development (TWD) as more
general than the fine-grained step of TFD, but also in contrast to the large-grained
phase of TLD. With our definition, we performed a multiple comparative study to
explore and describe TWD product changes, and the effects of those changes on two
attributes related to team speed and two attributes related to product quality, within
six long-term open-source projects. Our results indicate that when developers exer-cised some of their changes with automated tests, on average they made significantly
larger changes over time while significantly reducing their product’s complexity.
And, when they exercised all of their changes with tests, on average they made
significantly smaller changes over time. We interpret these results to indicate that
practicing TWD supports faster simplification of a product. Therefore, we conclude
that teams that need to reduce their product’s complexity can benefit from practicing
TWD.

没太明白TWD是什么意思？同时结论：We defined Test-With Development (TWD) as more
general than the fine-grained step of TFD, but also in contrast to the large-grained
phase of TLD.是什么意思？
谢谢！