tsserver support for a virtual filesystem

src/compiler/sys.ts

@@ -1221,7 +1221,11 @@ namespace ts {
      * patch writefile to create folder before writing the file
      */
     /*@internal*/
-    export function patchWriteFileEnsuringDirectory(sys: System) {
+    export function patchWriteFileEnsuringDirectory(sys: {
+        writeFile(path: string, data: string, writeByteOrderMark?: boolean): void;
+        directoryExists(path: string): boolean;
+        createDirectory(path: string): void;
+    }) {
         // patch writefile to create folder before writing the file
         const originalWriteFile = sys.writeFile;
         sys.writeFile = (path, data, writeBom) =>

src/harness/documentsUtil.ts

@@ -184,4 +184,4 @@ namespace documents {
             return vlq;
         }
     }
-}
+}

src/harness/fakesHosts.ts

@@ -589,4 +589,3 @@ Actual All:: ${JSON.stringify(this.diagnostics.slice().map(diagnosticToText), /*
         }
     }
 }
-

src/harness/harnessLanguageService.ts

@@ -994,6 +994,7 @@ namespace Harness.LanguageService {
             const serverHost = new SessionServerHost(clientHost);
             const opts: ts.server.SessionOptions = {
                 host: serverHost,
+                fshost: undefined, // TODO: fshost tests will want to provide this for testing language service?
                 cancellationToken: ts.server.nullCancellationToken,
                 useSingleInferredProject: false,
                 useInferredProjectPerProjectRoot: false,

src/harness/tsconfig.json

@@ -16,6 +16,7 @@
         { "path": "../jsTyping" },
         { "path": "../server" },
         { "path": "../typingsInstallerCore" },
+        { "path": "../vfs" },
         { "path": "../deprecatedCompat" },
     ],
 

src/harness/util.ts

@@ -125,4 +125,4 @@ namespace Utils {
         });
         return { resolve, reject, promise };
     }
-}
+}