Add option to remove trailing comma

This option is available in prettier so implementing it is trivial.
Needs the 'estree' prettier plugin, which is responsible for formatting
JSON. As a result, this might increase the size of the language server.

eg. in the following, when 'yaml.format.trailingComma` is set to `false`, the last comma should be removed:

```yaml
{
  key: 'value',
  food: 'raisins',
  airport: 'YYZ',
  lightened_bulb: 'illuminating',
}
```

See redhat-developer/vscode-yaml#1112

Signed-off-by: David Thompson <davthomp@redhat.com>

Author: datho7561

package.json

@@ -28,7 +28,7 @@
   "dependencies": {
     "ajv": "^8.11.0",
     "lodash": "4.17.21",
-    "prettier": "^3.0.0",
+    "prettier": "^3.5.0",
     "request-light": "^0.5.7",
     "vscode-json-languageservice": "4.1.8",
     "vscode-languageserver": "^9.0.0",

src/languageserver/handlers/settingsHandlers.ts

@@ -107,6 +107,10 @@ export class SettingsHandler {
           this.yamlSettings.yamlFormatterSettings.bracketSpacing = settings.yaml.format.bracketSpacing;
         }
 
+        if (settings.yaml.format.trailingComma !== undefined) {
+          this.yamlSettings.yamlFormatterSettings.trailingComma = settings.yaml.format.trailingComma;
+        }
+
         if (settings.yaml.format.enable !== undefined) {
           this.yamlSettings.yamlFormatterSettings.enable = settings.yaml.format.enable;
         }

src/languageservice/services/yamlFormatter.ts

@@ -7,7 +7,8 @@
 import { Range, Position, TextEdit, FormattingOptions } from 'vscode-languageserver-types';
 import { CustomFormatterOptions, LanguageSettings } from '../yamlLanguageService';
 import { Options } from 'prettier';
-import * as parser from 'prettier/plugins/yaml';
+import * as yamlPlugin from 'prettier/plugins/yaml';
+import * as estreePlugin from 'prettier/plugins/estree';
 import { format } from 'prettier/standalone';
 import { TextDocument } from 'vscode-languageserver-textdocument';
 
@@ -33,7 +34,7 @@ export class YAMLFormatter {
 
       const prettierOptions: Options = {
         parser: 'yaml',
-        plugins: [parser],
+        plugins: [yamlPlugin, estreePlugin],
 
         // --- FormattingOptions ---
         tabWidth: (options.tabWidth as number) || options.tabSize,
@@ -44,6 +45,7 @@ export class YAMLFormatter {
         // 'preserve' is the default for Options.proseWrap. See also server.ts
         proseWrap: 'always' === options.proseWrap ? 'always' : 'never' === options.proseWrap ? 'never' : 'preserve',
         printWidth: options.printWidth,
+        trailingComma: options.trailingComma === false ? 'none' : 'all',
       };
 
       const formatted = await format(text, prettierOptions);

src/languageservice/yamlLanguageService.ts

@@ -151,6 +151,7 @@ export interface SchemaConfiguration {
 export interface CustomFormatterOptions {
   singleQuote?: boolean;
   bracketSpacing?: boolean;
+  trailingComma?: boolean;
   proseWrap?: string;
   printWidth?: number;
   enable?: boolean;

src/yamlSettings.ts

@@ -69,6 +69,7 @@ export class SettingsState {
     bracketSpacing: true,
     proseWrap: 'preserve',
     printWidth: 80,
+    trailingComma: true,
     enable: true,
   } as CustomFormatterOptions;
   yamlShouldHover = true;

test/formatter.test.ts

@@ -5,9 +5,10 @@
 import { setupLanguageService, setupTextDocument } from './utils/testHelper';
 import { ServiceSetup } from './utils/serviceSetup';
 import * as assert from 'assert';
-import { TextEdit } from 'vscode-languageserver-types';
+import { FormattingOptions, TextEdit } from 'vscode-languageserver-types';
 import { SettingsState, TextDocumentTestManager } from '../src/yamlSettings';
 import { LanguageHandlers } from '../src/languageserver/handlers/languageHandlers';
+import { CustomFormatterOptions } from '../src';
 
 describe('Formatter Tests', () => {
   let languageHandler: LanguageHandlers;
@@ -60,6 +61,42 @@ describe('Formatter Tests', () => {
         assert.equal(edits[0].newText, 'comments: >\n  test test test\n  test test test\n  test test test\n  test test test\n');
       });
 
+      it('Formatting handles trailing commas (enabled)', async () => {
+        const content = `{
+  key: 'value',
+  food: 'raisins',
+  airport: 'YYZ',
+  lightened_bulb: 'illuminating',
+}
+`;
+        const edits = await parseSetup(content, { singleQuote: true });
+        assert.equal(edits[0].newText, content);
+      });
+
+      it('Formatting handles trailing commas (disabled)', async () => {
+        const content = `{
+  key: 'value',
+  food: 'raisins',
+  airport: 'YYZ',
+  lightened_bulb: 'illuminating',
+}
+`;
+        const edits = await parseSetup(content, {
+          singleQuote: true,
+          trailingComma: false,
+        });
+        assert.equal(
+          edits[0].newText,
+          `{
+  key: 'value',
+  food: 'raisins',
+  airport: 'YYZ',
+  lightened_bulb: 'illuminating'
+}
+`
+        );
+      });
+
       it('Formatting uses tabSize', async () => {
         const content = `map:
   k1: v1

yarn.lock

@@ -2675,10 +2675,10 @@ prettier-linter-helpers@^1.0.0:
   dependencies:
     fast-diff "^1.1.2"
 
-prettier@^3.0.0:
-  version "3.3.1"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.3.1.tgz#e68935518dd90bb7ec4821ba970e68f8de16e1ac"
-  integrity sha512-7CAwy5dRsxs8PHXT3twixW9/OEll8MLE0VRPCJyl7CkS6VHGPSlsVaWTiASPTyGyYRyApxlaWTzwUxVNrhcwDg==
+prettier@^3.5.0:
+  version "3.5.3"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.5.3.tgz#4fc2ce0d657e7a02e602549f053b239cb7dfe1b5"
+  integrity sha512-QQtaxnoDJeAkDvDKWCLiwIXkTgRhwYDEQCghU9Z6q03iyek/rxRh/2lC3HB7P8sWT2xC/y5JDctPLBIGzHKbhw==
 
 process-on-spawn@^1.0.0:
   version "1.0.0"