Misc. good test thoughts

content/notes/good-tests/index.md

@@ -14,19 +14,15 @@ _(Notes for a Viget article I'm putting together)_
     * But ideally you're testing the full integration of UI + API
 * Unit tests
   * Put complex logic into easily testable objects/functions
+  * This is where [TDD][1] can come into play
   * Avoid over-stubbing/mocking -- what are you even testing
+    * It is OK to go down the stack in your unit tests
 * Integration tests
   * You need proper end-to-end testing
   * Set up your data (fresh per test)
   * Visit a page
   * Interact with it
   * Make assertions about the results
-* Third-party/network calls
-  * VCR is … OK but can become a maintenance problem
-  * Block access to the web
-  * Create stub objects to stand in for network calls
-  * Use [JSON Schema][1] to ensure stub stays in sync
-  * This will lead to more reliable tests and also more robust code
 * Coverage
   * We shoot for 100% in SimpleCov (So all the Ruby is tested)
   * Some consider this too high or too burdensome -- I don't
@@ -34,12 +30,24 @@ _(Notes for a Viget article I'm putting together)_
     * If it's, say, 94%, and you add 100 lines, six of those can be untested -- hope they're perfect!
     * In other words, at less than 100% coverage, you don't know if your new feature is fully covered or not
   * Occasionally you have to ignore some code -- e.g. something that only runs in production
+* Third-party/network calls
+  * Major libraries often have mock services (e.g. [stripe-mock][2])
+  * VCR is … OK but can become a maintenance problem
+    * Block access to the web
+  * A better approach
+    * Move your integration code into a module
+    * Create a second stub module with the same API
+    * Use [JSON Schema][3] to ensure stub stays in sync (i.e. both the real client and the stub client validate against the schema)
+    * This will lead to more reliable tests and also more robust code
 * Flaky tests are bad
   * They eat up a lot of development time (esp. as build times increase)
   * Try to stay on top of them and squash them as they arise
   * Some frameworks have `retry` options/libraries that can help (bandage not cure)
   * In general, though, flaky tests suck and generally indicate lack of quality with either your code or your tools
+    * So write better code or pick better tools
 
-[1]: https://json-schema.org/
+[3]: https://json-schema.org/
+[1]: https://en.wikipedia.org/wiki/Test-driven_development
+[2]: https://github.com/stripe/stripe-mock
 
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