build: add visual regression testing

add image and dom snapshot comparison for storybook components

image snapshot comparison can been flaky and produce many
false-positives. a higher threshold has been used to mitigate this
although it may not identify all regressions. DOM snapshots
supplement images to increase the likelihood of capturing
regressions.

.github/workflows/playwright.yml

@@ -0,0 +1,27 @@
+name: Playwright Tests
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+jobs:
+  test:
+    timeout-minutes: 60
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-node@v3
+      with:
+        node-version: 18
+    - name: Install dependencies
+      run: yarn
+    - name: Install Playwright Browsers
+      run: yarn playwright install --with-deps
+    - name: Run Storybook tests
+      run: yarn test-storybook:ci
+    - uses: actions/upload-artifact@v3
+      if: always()
+      with:
+        name: playwright-report
+        path: playwright-report/
+        retention-days: 30

.storybook/test-runner.ts

@@ -0,0 +1,29 @@
+import type { TestRunnerConfig } from "@storybook/test-runner";
+import { toMatchImageSnapshot } from 'jest-image-snapshot';
+
+const customSnapshotsDir = `${process.cwd()}/__snapshots__`;
+
+
+const config: TestRunnerConfig = {
+    setup() {
+        expect.extend({ toMatchImageSnapshot });
+    },
+    async postRender(page, context) {
+        // DOM Snapshot
+        const elementHandler = await page.$('#storybook-root');
+        if (elementHandler) {
+            const innerHTML = await elementHandler.innerHTML();
+            expect(innerHTML).toMatchSnapshot();
+        }
+        // Image Snapshop
+        const image = await page.screenshot();
+        expect(image).toMatchImageSnapshot({
+            customSnapshotsDir,
+            customSnapshotIdentifier: context.id,
+            failureThresholdType: 'percent',
+            failureThreshold: 0.002,
+        });
+    },
+};
+
+export default config;

package.json

@@ -9,7 +9,9 @@
     "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
     "check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",
     "storybook": "storybook dev -p 6006",
-    "build-storybook": "storybook build"
+    "build-storybook": "storybook build",
+    "test-storybook": "test-storybook",
+    "test-storybook:ci": "concurrently -k -s first -n \"SB,TEST\" -c \"magenta,blue\" \"yarn build-storybook --quiet && npx http-server storybook-static --port 6006 --silent\" \"wait-on tcp:6006 && yarn test-storybook --maxWorkers=2\""
   },
   "devDependencies": {
     "@storybook/addon-a11y": "^7.4.5",
@@ -19,12 +21,16 @@
     "@storybook/blocks": "^7.4.5",
     "@storybook/svelte": "^7.4.5",
     "@storybook/sveltekit": "^7.4.5",
+    "@storybook/test-runner": "^0.13.0",
     "@storybook/testing-library": "^0.2.1",
     "@sveltejs/adapter-auto": "^2.0.0",
     "@sveltejs/adapter-node": "^1.2.3",
     "@sveltejs/kit": "^1.5.0",
     "@tailwindcss/typography": "^0.5.10",
+    "@types/jest-image-snapshot": "^6.2.1",
+    "@types/node": "^20.8.2",
     "autoprefixer": "^10.4.16",
+    "jest-image-snapshot": "^6.2.0",
     "postcss": "^8.4.30",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",

src/lib/components/__snapshots__/Navbar.stories.ts.snap

@@ -0,0 +1,76 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Navbar Default smoke-test 1`] = `
+<div class="navbar bg-neutral">
+  <div class="flex-1">
+    <h4>
+      <span class="primary">
+        git
+      </span>
+      <span class>
+        together
+      </span>
+      <span class>
+        .xyz
+      </span>
+    </h4>
+  </div>
+  <div class="flex-none gap-4">
+    <div class="btn btn-primary normal-case">
+      Sign up
+    </div>
+    <button class="btn btn-outline normal-case">
+      Login
+    </button>
+  </div>
+</div>
+`;
+
+exports[`Navbar NIP07Exists smoke-test 1`] = `
+<div class="navbar bg-neutral">
+  <div class="flex-1">
+    <h4>
+      <span class="primary">
+        git
+      </span>
+      <span class>
+        together
+      </span>
+      <span class>
+        .xyz
+      </span>
+    </h4>
+  </div>
+  <div class="flex-none gap-4">
+    <button class="btn btn-outline normal-case">
+      Login
+    </button>
+  </div>
+</div>
+`;
+
+exports[`Navbar NoNIP07 smoke-test 1`] = `
+<div class="navbar bg-neutral">
+  <div class="flex-1">
+    <h4>
+      <span class="primary">
+        git
+      </span>
+      <span class>
+        together
+      </span>
+      <span class>
+        .xyz
+      </span>
+    </h4>
+  </div>
+  <div class="flex-none gap-4">
+    <div class="btn btn-primary normal-case">
+      Sign up
+    </div>
+    <button class="btn btn-outline normal-case">
+      Login
+    </button>
+  </div>
+</div>
+`;