chore: configure chromatic snapshot tests (#896)

Resolves: #444

Summary:

This commit installs and configures a GH action for chromatic. Chromatic
is used for snapshot testing build-over-build.

Details:

* chore: install chromatic

* chore: add chromatic package.json script

Suggested by the docs for convenience so that we can run chromatic like:

```console
yarn run chromatic ...
```

* chore: gitignore storybook builds

* ci: configure chromatic

This action configures chromatic to run in CI on pushes to all branches.
By running this in CI, we get the following:

- snapshot (build-over-build)
- checks in our CI

The snapshots and build-over-build behavior are per branch; this way we
can work on a feature branch without worrying about changes being made
to mainline independently.

* chore: remove manual storybook build from CI

This is now the responsibility of Chromatic

.github/workflows/chromatic.yaml

@@ -0,0 +1,51 @@
+# Note: Chromatic is a separate workflow for coder.yaml as suggested by the
+# chromatic docs. Explicitly, Chromatic works best on 'push' instead of other
+# event types (like pull request), keep in mind that it works build-over-build
+# by storing snapshots.
+#
+# SEE: https://www.chromatic.com/docs/ci
+name: "Chromatic"
+
+# Chromatic works best with push events, not pull_request or other event types.
+on: push
+
+jobs:
+  chromatic-deployment:
+    # REMARK: this is only used to build storybook and deploy it to Chromatic.
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          # Required by Chromatic for build-over-build history, otherwise we
+          # only get 1 commit on shallow checkout.
+          fetch-depth: 0
+
+      - name: Install dependencies
+        run: cd site && yarn
+
+      # This step is not meant for mainline because any detected changes to
+      # storybook snapshots will require manual approval/review in order for
+      # the check to pass. This is desired in PRs, but not in mainline.
+      - name: Publish to Chromatic (non-mainline)
+        if: github.ref != 'refs/heads/main'
+        uses: chromaui/action@v1
+        with:
+          buildScriptName: "storybook:build"
+          projectToken: ${{ secrets.CHROMATIC_PROJECT_TOKEN }}
+          workingDir: "./site"
+
+      # This is a separate step for mainline only that auto accepts and changes
+      # instead of holding CI up. Since we squash/merge, this is defensive to
+      # avoid the same changeset from requiring review once squashed into
+      # main. Chromatic is supposed to be able to detect that we use squash
+      # commits, but it's good to be defensive in case, otherwise CI remains
+      # infinitely "in progress" in mainline unless we re-review each build.
+      - name: Publish to Chromatic (mainline)
+        if: github.ref == 'refs/heads/main'
+        uses: chromaui/action@v1
+        with:
+          autoAcceptChanges: true
+          buildScriptName: "storybook:build"
+          projectToken: ${{ secrets.CHROMATIC_PROJECT_TOKEN }}
+          workingDir: "./site"

.github/workflows/coder.yaml

@@ -387,10 +387,6 @@ jobs:
         run: yarn build
         working-directory: site
 
-      - name: Build Storybook
-        run: yarn storybook:build
-        working-directory: site
-
       - run: yarn test:coverage
         working-directory: site
 

.gitignore

@@ -25,6 +25,7 @@ site/test-results/
 site/yarn-error.log
 coverage/
 site/**/*.typegen.ts
+site/build-storybook.log
 
 # Build
 dist/

site/package.json

@@ -7,6 +7,7 @@
     "postinstall": "yarn typegen",
     "build": "NODE_ENV=production webpack build --config=webpack.prod.ts",
     "build:analyze": "NODE_ENV=production webpack --profile --progress --json --config=webpack.prod.ts > out/stats.json && webpack-bundle-analyzer out/stats.json out",
+    "chromatic": "chromatic",
     "dev": "webpack-dev-server --config=webpack.dev.ts",
     "format:check": "prettier --check '**/*.{css,html,js,json,jsx,md,ts,tsx,yaml,yml}'",
     "format:write": "prettier --write '**/*.{css,html,js,json,jsx,md,ts,tsx,yaml,yml}'",
@@ -59,6 +60,7 @@
     "@typescript-eslint/eslint-plugin": "5.17.0",
     "@typescript-eslint/parser": "5.17.0",
     "@xstate/cli": "0.1.5",
+    "chromatic": "6.5.3",
     "copy-webpack-plugin": "10.2.4",
     "css-loader": "6.7.1",
     "css-minimizer-webpack-plugin": "3.4.1",

site/yarn.lock

@@ -5484,6 +5484,11 @@ chownr@^2.0.0:
   resolved "https://registry.yarnpkg.com/chownr/-/chownr-2.0.0.tgz#15bfbe53d2eab4cf70f18a8cd68ebe5b3cb1dece"
   integrity sha512-bIomtDF5KGpdogkLd9VspvFzk9KfpyyGlS8YFVZl7TGPBHL5snIOnxeshwVgPteQ9b4Eydl+pVbIyE1DcvCWgQ==
 
+chromatic@6.5.3:
+  version "6.5.3"
+  resolved "https://registry.yarnpkg.com/chromatic/-/chromatic-6.5.3.tgz#dd96e6df6d2ed9d0c79277dc18b06a089080ce62"
+  integrity sha512-6Wy2lsNaojY5wTvobE3WV5VrQ5oP7B8kal6zWGrxu9g7Qbenb2cTcQ5SYgQY7tzT0Ed0zeHVyQm4TMmKz+XfXA==
+
 chrome-trace-event@^1.0.2:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/chrome-trace-event/-/chrome-trace-event-1.0.3.tgz#1015eced4741e15d06664a957dbbf50d041e26ac"