The compiler also doesn’t know anything about how to handle external dependencies, such as third-party JAR files in Java. Often the best we can do without a build system is to download the dependency from the internet, stick it in a lib folder on the hard drive, and configure the compiler to read libraries from that directory. Over time, it’s easy to forget what libraries we put in there, where th... [更多...]

能够立即有效地浏览整个代码库意味着很容易找到相关的库来重用和好的例子来复制。 Most of the time, developers won’t notice when indices are out of date. They only care about a small subset of code, and even for that they generally won’t know whether there is more recent code. However, for the cases in which they wrote or reviewed the corresponding change, being out of sync can cause a lot of confusion. It tends not to matter whether the ... [更多...]

In all of this thinking, we’re assigning special significance to the trunk branch. But of course, “trunk” in your VCS is only the technology default, and an organization can choose different policies on top of that. Perhaps the default branch has been abandoned and all work actually happens on some custom development branch—other than needing to provide a branch name in more operations, there’s no... [更多...]

Our discussion of deprecation begins from the fundamental premise that code is a liability, not an asset. After all, if code were an asset, why should we even bother spending time trying to turn down and remove obsolete systems? Code has costs, some of which are borne in the process of creating a system, but many other costs are borne as a system is maintained across its lifetime. These ongoing co... [更多...]

Unit tests are limited by the imagination of the engineer writing them. That is, they can only test for anticipated behaviors and inputs. However, issues that users find with a product are mostly unanticipated (otherwise it would be unlikely that they would make it to end users as issues). This fact suggests that different test techniques are needed to test for unanticipated behaviors.（单元测试受到编写它们的... [更多...]

Writing testable code requires an upfront investment. It is especially critical early in the lifetime of a codebase because the later testability is taken into account, the more difficult it is to apply to a codebase. Code written without testing in mind typically needs to be refactored or rewritten before you can add appropriate tests.（编写可测试代码需要前期投入。在代码库生命周期的早期，这一点尤其重要，因为越晚考虑可测试性，就越难应用到代码库中。在没有考虑... [更多...]

At Google, we’ve found that engineers sometimes need to be persuaded that testing via public APIs is better than testing against implementation details. The reluctance is understandable because it’s often much easier to write tests focused on the piece of code you just wrote rather than figuring out how that code affects the system as a whole. Nevertheless, we have found it valuable to encourage s... [更多...]

Unlike the QA processes of yore, in which rooms of dedicated software testers pored over new versions of a system, exercising every possible behavior, the engineers who build systems today play an active and integral role in writing and running automated tests for their own code. Even in companies where QA is a prominent organization, developer-written tests are commonplace. At the speed and scale... [更多...]

Instead, before you begin writing, you should (formally or informally) identify the audience(s) your documents need to satisfy. A design document might need to persuade decision makers. A tutorial might need to provide very explicit instructions to someone utterly unfamiliar with your codebase. An API might need to provide complete and accurate reference information for any users of that API, be t... [更多...]

Google’s culture, like that of a lot of software companies, is based on giving engineers wide latitude in how they do their jobs. There is a recognition that strict processes tend not to work well for a dynamic company needing to respond quickly to new technologies, and that bureaucratic rules tend not to work well with creative professionals. Code review, however, is a mandate, one of the few bla... [更多...]