add label details support to fourslash

Author: gabritto

src/harness/fourslashImpl.ts

@@ -983,6 +983,8 @@ namespace FourSlash {
                 assert.equal<boolean | undefined>(actual.isPackageJsonImport, expected.isPackageJsonImport, `At entry ${actual.name}: Expected 'isPackageJsonImport' properties to match`);
             }
 
+            assert.equal(actual.labelDetails?.description, expected.labelDetails?.description, `At entry ${actual.name}: Expected 'labelDetails.description' properties to match`);
+            assert.equal(actual.labelDetails?.detail, expected.labelDetails?.detail, `At entry ${actual.name}: Expected 'labelDetails.detail' properties to match`);
             assert.equal(actual.hasAction, expected.hasAction, `At entry ${actual.name}: Expected 'hasAction' properties to match`);
             assert.equal(actual.isRecommended, expected.isRecommended, `At entry ${actual.name}: Expected 'isRecommended' properties to match'`);
             assert.equal(actual.isSnippet, expected.isSnippet, `At entry ${actual.name}: Expected 'isSnippet' properties to match`);

src/harness/fourslashInterfaceImpl.ts

@@ -1719,10 +1719,16 @@ namespace FourSlashInterface {
         readonly text?: string;
         readonly documentation?: string;
         readonly sourceDisplay?: string;
+        readonly labelDetails?: ExpectedCompletionEntryLabelDetails;
         readonly tags?: readonly ts.JSDocTagInfo[];
         readonly sortText?: ts.Completions.SortText;
     }
 
+    export interface ExpectedCompletionEntryLabelDetails {
+        detail?: string;
+        description?: string;
+    }
+
     export type ExpectedExactCompletionsPlus = readonly ExpectedCompletionEntry[] & {
         plusFunctionName: string,
         plusArgument: readonly ExpectedCompletionEntry[]

tests/cases/fourslash/fourslash.ts

@@ -700,6 +700,12 @@ declare namespace FourSlashInterface {
         readonly documentation?: string;
         readonly tags?: ReadonlyArray<JSDocTagInfo>;
         readonly sourceDisplay?: string;
+        readonly labelDetails?: ExpectedCompletionEntryLabelDetails;
+    }
+
+    export interface ExpectedCompletionEntryLabelDetails {
+        detail?: string;
+        description?: string;
     }
 
     interface VerifySignatureHelpOptions {