05/01: add solution

Author: kettanaito

.gitignore

@@ -12,6 +12,7 @@ data.db
 **/*.tsbuildinfo
 __screenshots__
 *.sqlite
+test-profiles
 
 # in a real app you'd want to not commit the .env
 # file as well, but since this is for a workshop

exercises/02.environment/01.solution.custom-environment/README.mdx

@@ -1 +1,7 @@
 # Custom test environment
+
+## Questions to answer
+
+- When do I need custom environment over global test setup (`globalSetup`)? What's the practical difference?
+  - `globalSetup` runs _once_ for the whole test run. Test environment runs for each worker.
+  - `globalSetup` runs on the _main thread_, outside of the test workers. This means you cannot modify `globalThis` from the global setup because it doesn't share the thread with the test worker. You can do that with `setupFiles` because of when they run.

exercises/02.environment/01.solution.custom-environment/emv.ts

@@ -0,0 +1,23 @@
+import { Environment, builtinEnvironments } from 'vitest/environments'
+
+export default <Environment>{
+	name: 'custom-env',
+	transformMode: 'ssr',
+	async setup(global, options) {
+		const { teardown } = await builtinEnvironments.node.setup(global, options)
+
+		return {
+			teardown,
+		}
+	},
+}
+
+/**
+
+1. Polyfill something unavailable in the main environment.
+
+2. Perform a test suite-wide side effect necessary for the tests to run.
+
+3. Testing code that's not meant to run in Node/browser (e.g. edge, Cloudflare Workers, etc).
+
+*/

exercises/02.environment/02.solution.applying-environments/README.mdx

@@ -1 +1,3 @@
 # Applying environments
+
+- https://vitest.dev/config/#environmentmatchglobs

exercises/05.performance/01.solution.profiling-slow-tests/README.mdx

@@ -1 +1,14 @@
 # Profiling slow tests
+
+## Step 0. Know your test runner
+
+Know the steps that Vitest takes to run your test. Any step may introduce performance degradation. Know the main thread (where Vite and `globalSetup` runs), the forks (where test environment and `setupFiles` run), test transformation, test collection, and tests themselves.
+
+## Step 1. Use aggregated test metrics:
+
+```
+Duration  2.19s (transform 16ms, setup 0ms, collect 10ms, tests 2.00s, environment 0ms, prepare 46ms)
+//                                                        ^^^^^^^^^^^
+```
+
+This is a good overlook at which areas of your test take how much time. Understanding what each area does sets up your map for future debugging.

exercises/05.performance/01.solution.profiling-slow-tests/package.json

@@ -4,10 +4,12 @@
   "scripts": {
     "dev": "vite",
     "test": "vitest",
+    "test:profile": "vitest-profiler npm test",
     "build": "vite build"
   },
   "devDependencies": {
     "vite": "^6.0.7",
-    "vitest": "^3.0.5"
+    "vitest": "^3.0.5",
+    "vitest-profiler": "^0.1.7"
   }
 }