fix(cli): wizard addArrayProp should not add double comma

Author: johnjenkins

packages/cli/src/_test_/config-editor.spec.ts

@@ -272,6 +272,20 @@ export const config: Config = {
       expect(result).toContain('sass()');
     });
 
+    it('does not introduce a double comma when the last property already has a trailing comma', async () => {
+      mockConfig(`export const config: Config = {
+  namespace: 'MyLib',
+  outputTargets: [{ type: 'loader-bundle' }],
+};
+`);
+      const editor = await openStencilConfig(CONFIG_PATH);
+      editor.addPlugin('sass()');
+      await editor.save();
+
+      const result = savedText();
+      expect(result).not.toContain(',,');
+    });
+
     it('supports plugin with options', async () => {
       mockConfig(`export const config: Config = {
   namespace: 'MyLib',

packages/cli/src/wizard/config-editor.ts

@@ -156,8 +156,9 @@ export async function openStencilConfig(configPath: string): Promise<StencilConf
     if (lastProp) {
       let insertPos = lastProp.getEnd();
       const trailingComma = text.slice(insertPos).match(/^\s*,/);
+      const separator = trailingComma ? '' : ',';
       if (trailingComma) insertPos += trailingComma[0].length;
-      text = `${text.slice(0, insertPos)},\n${propIndent}${newProp}${text.slice(insertPos)}`;
+      text = `${text.slice(0, insertPos)}${separator}\n${propIndent}${newProp}${text.slice(insertPos)}`;
     } else {
       // Empty config object
       const insertPos = configObj.getEnd() - 1; // before }