diff --git a/src/harness/unittests/tsserverProjectSystem.ts b/src/harness/unittests/tsserverProjectSystem.ts
index 06e2beeaaa6..e594093605a 100644
--- a/src/harness/unittests/tsserverProjectSystem.ts
+++ b/src/harness/unittests/tsserverProjectSystem.ts
@@ -352,8 +352,6 @@ namespace ts.projectSystem {
         verifyDiagnostics(actual, []);
     }
 
-    const typeRootFromTsserverLocation = "/node_modules/@types";
-
     export function getTypeRootsFromLocation(currentDirectory: string) {
         currentDirectory = normalizePath(currentDirectory);
         const result: string[] = [];
@@ -401,7 +399,7 @@ namespace ts.projectSystem {
             const configFiles = flatMap(configFileLocations, location => [location + "tsconfig.json", location + "jsconfig.json"]);
             checkWatchedFiles(host, configFiles.concat(libFile.path, moduleFile.path));
             checkWatchedDirectories(host, [], /*recursive*/ false);
-            checkWatchedDirectories(host, ["/a/b/c", typeRootFromTsserverLocation], /*recursive*/ true);
+            checkWatchedDirectories(host, ["/a/b/c", ...getTypeRootsFromLocation(getDirectoryPath(appFile.path))], /*recursive*/ true);
         });
 
         it("can handle tsconfig file name with difference casing", () => {
@@ -4331,7 +4329,7 @@ namespace ts.projectSystem {
 
             function verifyCalledOnEachEntry(callback: CalledMaps, expectedKeys: Map<number>) {
                 const calledMap = calledMaps[callback];
-                assert.equal(calledMap.size, expectedKeys.size, `${callback}: incorrect size of map: Actual keys: ${arrayFrom(calledMap.keys())} Expected: ${arrayFrom(expectedKeys.keys())}`);
+                ts.TestFSWithWatch.verifyMapSize(callback, calledMap, arrayFrom(expectedKeys.keys()));
                 expectedKeys.forEach((called, name) => {
                     assert.isTrue(calledMap.has(name), `${callback} is expected to contain ${name}, actual keys: ${arrayFrom(calledMap.keys())}`);
                     assert.equal(calledMap.get(name).length, called, `${callback} is expected to be called ${called} times with ${name}. Actual entry: ${calledMap.get(name)}`);
@@ -4413,6 +4411,7 @@ namespace ts.projectSystem {
             }
             const f2Lookups = getLocationsForModuleLookup("f2");
             callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, f2Lookups, 1);
+            const typeRootLocations = getTypeRootsFromLocation(getDirectoryPath(root.path));
             const f2DirLookups = getLocationsForDirectoryLookup();
             callsTrackingHost.verifyCalledOnEachEntry(CalledMapsWithSingleArg.directoryExists, f2DirLookups);
             callsTrackingHost.verifyNoCall(CalledMapsWithSingleArg.getDirectories);
@@ -4423,7 +4422,7 @@ namespace ts.projectSystem {
             verifyImportedDiagnostics();
             const f1Lookups = f2Lookups.map(s => s.replace("f2", "f1"));
             f1Lookups.length = f1Lookups.indexOf(imported.path) + 1;
-            const f1DirLookups = ["/c/d", "/c", typeRootFromTsserverLocation];
+            const f1DirLookups = ["/c/d", "/c", ...typeRootLocations];
             vertifyF1Lookups();
 
             // setting compiler options discards module resolution cache
@@ -4475,7 +4474,7 @@ namespace ts.projectSystem {
             function getLocationsForDirectoryLookup() {
                 const result = createMap<number>();
                 // Type root
-                result.set(typeRootFromTsserverLocation, 1);
+                typeRootLocations.forEach(location => result.set(location, 1));
                 forEachAncestorDirectory(getDirectoryPath(root.path), ancestor => {
                     // To resolve modules
                     result.set(ancestor, 2);
diff --git a/src/harness/virtualFileSystemWithWatch.ts b/src/harness/virtualFileSystemWithWatch.ts
index c16f57235e4..ff782bbf7d2 100644
--- a/src/harness/virtualFileSystemWithWatch.ts
+++ b/src/harness/virtualFileSystemWithWatch.ts
@@ -95,7 +95,7 @@ namespace ts.TestFSWithWatch {
         }
     }
 
-    function getDiffInKeys(map: Map<any>, expectedKeys: ReadonlyArray<string>) {
+    function getDiffInKeys<T>(map: Map<T>, expectedKeys: ReadonlyArray<string>) {
         if (map.size === expectedKeys.length) {
             return "";
         }
@@ -122,8 +122,12 @@ namespace ts.TestFSWithWatch {
         return `\n\nNotInActual: ${notInActual}\nDuplicates: ${duplicates}\nInActualButNotInExpected: ${inActualNotExpected}`;
     }
 
-    function checkMapKeys(caption: string, map: Map<any>, expectedKeys: ReadonlyArray<string>) {
+    export function verifyMapSize(caption: string, map: Map<any>, expectedKeys: ReadonlyArray<string>) {
         assert.equal(map.size, expectedKeys.length, `${caption}: incorrect size of map: Actual keys: ${arrayFrom(map.keys())} Expected: ${expectedKeys}${getDiffInKeys(map, expectedKeys)}`);
+    }
+
+    function checkMapKeys(caption: string, map: Map<any>, expectedKeys: ReadonlyArray<string>) {
+        verifyMapSize(caption, map, expectedKeys);
         for (const name of expectedKeys) {
             assert.isTrue(map.has(name), `${caption} is expected to contain ${name}, actual keys: ${arrayFrom(map.keys())}`);
         }
@@ -548,7 +552,7 @@ namespace ts.TestFSWithWatch {
             const folder = this.toFolder(directoryName);
 
             // base folder has to be present
-            const base = getDirectoryPath(folder.fullPath);
+            const base = getDirectoryPath(folder.path);
             const baseFolder = this.fs.get(base) as Folder;
             Debug.assert(isFolder(baseFolder));
 
@@ -560,7 +564,7 @@ namespace ts.TestFSWithWatch {
             const file = this.toFile({ path, content });
 
             // base folder has to be present
-            const base = getDirectoryPath(file.fullPath);
+            const base = getDirectoryPath(file.path);
             const folder = this.fs.get(base) as Folder;
             Debug.assert(isFolder(folder));
 
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 3bb2ed11674..713188e9da8 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -7131,7 +7131,6 @@ declare namespace ts.server {
         enableLanguageService(): void;
         disableLanguageService(): void;
         getProjectName(): string;
-        abstract getProjectRootPath(): string | undefined;
         abstract getTypeAcquisition(): TypeAcquisition;
         getExternalFiles(): SortedReadonlyArray<string>;
         getSourceFile(path: Path): SourceFile;
@@ -7184,7 +7183,6 @@ declare namespace ts.server {
         addRoot(info: ScriptInfo): void;
         removeRoot(info: ScriptInfo): void;
         isProjectWithSingleRoot(): boolean;
-        getProjectRootPath(): string;
         close(): void;
         getTypeAcquisition(): TypeAcquisition;
     }
@@ -7211,7 +7209,6 @@ declare namespace ts.server {
         enablePlugins(): void;
         private enablePlugin(pluginConfigEntry, searchPaths);
         private enableProxy(pluginModuleFactory, configEntry);
-        getProjectRootPath(): string;
         /**
          * Get the errors that dont have any file name associated
          */
@@ -7237,11 +7234,9 @@ declare namespace ts.server {
     class ExternalProject extends Project {
         externalProjectName: string;
         compileOnSaveEnabled: boolean;
-        private readonly projectFilePath;
         excludedFiles: ReadonlyArray<NormalizedPath>;
         private typeAcquisition;
         getExcludedFiles(): ReadonlyArray<NormalizedPath>;
-        getProjectRootPath(): string;
         getTypeAcquisition(): TypeAcquisition;
         setTypeAcquisition(newTypeAcquisition: TypeAcquisition): void;
     }
@@ -7519,7 +7514,7 @@ declare namespace ts.server {
         private updateNonInferredProject<T>(project, newUncheckedFiles, propertyReader, newOptions, newTypeAcquisition, compileOnSave);
         private getOrCreateInferredProjectForProjectRootPathIfEnabled(info, projectRootPath);
         private getOrCreateSingleInferredProjectIfEnabled();
-        private createInferredProject(rootDirectoryForResolution, isSingleInferredProject?, projectRootPath?);
+        private createInferredProject(currentDirectory, isSingleInferredProject?, projectRootPath?);
         getScriptInfo(uncheckedFileName: string): ScriptInfo;
         private watchClosedScriptInfo(info);
         private stopWatchingScriptInfo(info);