Use string literal type for script kind names

Author: zhengbli

src/harness/harnessLanguageService.ts

@@ -496,7 +496,7 @@ namespace Harness.LanguageService {
             this.client = client;
         }
 
-        openFile(fileName: string, content?: string, scriptKindName?: string): void {
+        openFile(fileName: string, content?: string, scriptKindName?: "TS" | "JS" | "TSX" | "JSX"): void {
             super.openFile(fileName, content, scriptKindName);
             this.client.openFile(fileName, content, scriptKindName);
         }

src/server/client.ts

@@ -120,7 +120,7 @@ namespace ts.server {
             return response;
         }
 
-        openFile(fileName: string, content?: string, scriptKindName?: string): void {
+        openFile(fileName: string, content?: string, scriptKindName?: "TS" | "JS" | "TSX"  | "JSX"): void {
             var args: protocol.OpenRequestArgs = { file: fileName, fileContent: content, scriptKindName };
             this.processRequest(CommandNames.Open, args);
         }

src/server/protocol.d.ts

@@ -520,9 +520,9 @@ declare namespace ts.server.protocol {
         fileContent?: string;
         /**
          * Used to specify the script kind of the file explicitly. It could be one of the following:
-         *      ".ts", ".js", ".tsx", ".jsx"
+         *      "TS", "JS", "TSX", "JSX"
          */
-        scriptKindName?: string;
+        scriptKindName?: "TS" | "JS" | "TSX" | "JSX";
     }
 
     /**

src/server/session.ts

@@ -969,16 +969,16 @@ namespace ts.server {
                 const openArgs = <protocol.OpenRequestArgs>request.arguments;
                 let scriptKind: ScriptKind;
                 switch (openArgs.scriptKindName) {
-                    case ".ts":
+                    case "TS":
                         scriptKind = ScriptKind.TS;
                         break;
-                    case ".js":
+                    case "JS":
                         scriptKind = ScriptKind.JS;
                         break;
-                    case ".tsx":
+                    case "TSX":
                         scriptKind = ScriptKind.TSX;
                         break;
-                    case ".jsx":
+                    case "JSX":
                         scriptKind = ScriptKind.JSX;
                         break;
                 }

tests/cases/fourslash/server/openFileWithSyntaxKind.ts

@@ -14,6 +14,6 @@
 //// var t;
 //// t.
 
-goTo.file("test.ts", /*content*/ undefined, ".js");
+goTo.file("test.ts", /*content*/ undefined, "JS");
 goTo.eof();
 verify.completionListContains("toExponential");