ci: Integrate prettier formatting (#376)

So far, the code formatting was not checked by the CI. Now it is. To do
so, this commit introduces a new `format-check` npm command. I did not
use the `eslint-prettier` plugin because the guidance on
https://prettier.io/docs/en/integrating-with-linters.html recommends
against doing so.

Author: vogelsgesang

.bazelci/presubmit.yml

@@ -18,10 +18,6 @@ tasks:
       - npm ci
       - npm run compile
       - npm run check-lint
-      # TODO(allevato): Add a prettier check to verify that *.ts files don't
-      # differ from their prettier output. We need `prettier-tslint` so that
-      # prettier will obey our tslint config, but it doesn't support
-      # Typescript 3 yet.
-      # (https://github.com/azz/prettier-tslint/issues/18)
+      - npm run format-check
     build_targets:
       - "//:dummy_target_for_ci"

.prettierignore

@@ -1 +1,2 @@
 *.json
+src/protos/protos.js

eslint.config.js

@@ -182,5 +182,6 @@ module.exports = tseslint.config(
     rules: {
       // Re-enable as soon as we are using ES modules for this config file.
       "@typescript-eslint/no-var-requires": "off",
-    }
-  });
+    },
+  },
+);

package-lock.json

@@ -444,6 +444,8 @@
     "scripts": {
         "check-lint": "eslint .",
         "compile": "./scripts/build.sh",
+        "format-check": "prettier --check .",
+        "format-fix": "prettier --write .",
         "vscode:prepublish": "./scripts/build.sh",
         "watch": "./scripts/build.sh -watch"
     },
@@ -454,6 +456,7 @@
         "eslint": "^8.57.0",
         "eslint-config-prettier": "^9.1.0",
         "eslint-plugin-jsdoc": "^48.2.2",
+        "prettier": "^3.2.5",
         "typescript": "^5.4.4",
         "typescript-eslint": "^7.5.0"
     },
@@ -465,4 +468,4 @@
         "vscode-uri": "^3.0.2",
         "which": "^4.0.0"
     }
-}
+}

package.json

@@ -90,7 +90,8 @@ function getAbsoluteLabel(
 }
 
 export class BazelCompletionItemProvider
-  implements vscode.CompletionItemProvider {
+  implements vscode.CompletionItemProvider
+{
   private targets: string[] = [];
 
   /**