Pills

Short, standalone explanations of concepts that come up across the articles — read once, link to forever.

• Decoupling

  Reducing how much one part of a system needs to know about another, so each can change without dragging the other along with it.

• Dependency direction

  Which way an arrow points in a dependency diagram: toward the stable abstraction, not toward whichever concrete detail happens to be called.

• End-to-end test

  A test that drives a request through the real system the way a client would, over HTTP, through the real handler, into the real database, and asserts on the response.

• Seam

  A point in the code where you can change behavior without editing the code at that point, usually by passing in something different.

• Test fixtures

  Known, pre-loaded data a test runs against, so its assertions can rely on a predictable starting state instead of whatever happens to be in the database.