AI Chronicles #7: Configurable Client

In this weekly livestream series, Ted M. Young and I build an AI-powered role-playing game using React, Spring Boot, and Nullables. And, of course, plenty of discussion about design, architecture, and effective programming practices.

Watch us live every Monday! For details, see the event page. For more episode recordings, see the episode archive.

In this episode...

We turn to parsing the response returned from the “say” API, which will be the OpenAI response to a message. To do that, we add the ability to configure the nullable HttpClient so it returns predetermined responses from our tests. We discover that using the HTTP library's Response object provides a default Content Type, which we don't want for our tests, and deal with the window vs. Global implementation of fetch().

After we get everything working, we add types to make the TypeScript type checker happy. With that done, we're ready for the next episode, where we'll return to the Spring Boot back-end and implement the “say” API endpoint.


  • Ted spoke at the Kansas City Developer Conference (0:16)
  • Lack of Java-focused conferences in the USA (1:19)
  • Conferences in the USA vs. Europe/rest of world (2:10)
  • Trying to aim talks at the right level for the audience (4:38)
  • Ted's research to prepare for the AssertJ talk (6:05)
  • AssertJ assertions for Joda Money (7:23)
  • Joda Money project vs. JSR-354 Money & Currency (8:45)
  • Programming language cultures (10:34)
  • Checked exceptions and API design (12:20)
  • Language convention vs. enforced rules (14:02)
  • Why we wrap third-party libraries and objects (17:49)
  • Primitive Obsession (20:16)
  • Exploring and learning your tools (22:51)
  • Learning design from Martin Fowler's "Refactoring" book (23:25)
  • Small changes, small steps (24:39)
  • Loss of awareness of design? (25:32)
  • Reading books in a group (29:12)
  • Refactorings and their trade-offs (30:29)
  • James talks about CTO vs. VP Engineering (31:56)
  • Reviewing where we left off in the code (34:30)
  • Sidebar: forgetting what you were doing in a project (39:27)
  • Planning and doing one thing at a time (41:01)
  • Context-switching in a heavy pull-request environment (41:48)
  • Feedback loops and eXtreme Programming (42:55)
  • Testing parsing of responses in the BackEndClient (45:43)
  • Sidebar: who holds the state? (49:06)
  • Configuring the answer for the BackEndClient (50:05)
  • Test-driving HttpClient's default response (54:45)
  • Where is that text/plain content type coming from? (1:05:18)
  • Sidebar: differencing in test output and coding in VB, and QB (1:06:10)
  • Should our stubbed fetch() return content length? (1:09:06)
  • Configuring HttpClient's response for an endpoint (1:10:48)
  • Discovered need to specify full endpoint URL, not just path (1:14:58)
  • Test failed as expected, on to implementation (1:17:37)
  • Who has fetch()? Window vs. Global vs. globalThis (1:21:26)
  • Using Optional chaining and nullish coalescing (1:29:23)
  • Troubleshooting "headers.entries" (1:30:09)
  • Specifying content-type in configured response (1:36:30)
  • Generalize to allow partially configured response (1:42:10)
  • Sidebar on readability of "advanced" syntax in code (1:48:40)
  • Allowing multiple endpoints to be configured (1:52:13)
  • Avoiding real-world values in configuration tests (1:58:42)
  • Spiking some attempts at improving code (1:59:20)
  • Adding types to make TypeScript type checker happy (2:05:10)
  • Defining own type often easier than reusing library types (2:14:24)
  • Back to the BackEndClient failing test (2:16:12)
  • Refactor test code now that it passes (2:20:36)
  • Reviewing the test refactor (2:30:45)
  • BackEndClient is done: updated the plan and integrated (2:31:32)
  • Next time we'll start with the Spring Boot back-end endpoint (2:33:10)
  • Review our work (2:34:05)
  • Downside of sociable vs. isolated tests with mocks (2:35:02)
  • The Rubber Chicken (2:38:18)

Source code

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