Allow test harness to force-enable additional features

packages/tailwindcss-language-server/src/projects.ts

@@ -469,6 +469,13 @@ export async function createProjectService(
       log(`supported features: ${JSON.stringify(features)}`)
       state.features = features
 
+      if (params.initializationOptions?.testMode) {
+        state.features = [
+          ...state.features,
+          ...(params.initializationOptions.additionalFeatures ?? []),
+        ]
+      }
+
       if (!features.includes('css-at-theme')) {
         tailwindcss = tailwindcss.default ?? tailwindcss
       }
@@ -695,6 +702,14 @@ export async function createProjectService(
         state.v4Fallback = true
         state.jit = true
         state.features = features
+
+        if (params.initializationOptions?.testMode) {
+          state.features = [
+            ...state.features,
+            ...(params.initializationOptions.additionalFeatures ?? []),
+          ]
+        }
+
         state.modules = {
           tailwindcss: { version: tailwindcssVersion, module: tailwindcss },
           postcss: { version: null, module: null },

packages/tailwindcss-language-server/tests/utils/client.ts

@@ -47,6 +47,7 @@ import { clearLanguageBoundariesCache } from '@tailwindcss/language-service/src/
 import { DefaultMap } from '../../src/util/default-map'
 import { connect, ConnectOptions } from './connection'
 import type { DeepPartial } from '@tailwindcss/language-service/src/types'
+import type { Feature } from '@tailwindcss/language-service/src/features'
 
 export interface DocumentDescriptor {
   /**
@@ -170,6 +171,14 @@ export interface ClientOptions extends ConnectOptions {
    * Settings to provide the server immediately when it starts
    */
   settings?: DeepPartial<Settings>
+
+  /**
+   * Additional features to force-enable
+   *
+   * These should normally be enabled by the server based on the project
+   * and the Tailwind CSS version it detects
+   */
+  features?: Feature[]
 }
 
 export interface Client extends ClientWorkspace {
@@ -394,6 +403,7 @@ export async function createClient(opts: ClientOptions): Promise<Client> {
     workspaceFolders,
     initializationOptions: {
       testMode: true,
+      additionalFeatures: opts.features,
       ...opts.options,
     },
   })