Refactor tests so its easy to edit and reason about them

src/harness/virtualFileSystemWithWatch.ts

@@ -196,8 +196,8 @@ interface Array<T> {}`
         }
     }
 
-    export function checkWatchedFiles(host: TestServerHost, expectedFiles: string[]) {
-        checkMapKeys("watchedFiles", host.watchedFiles, expectedFiles);
+    export function checkWatchedFiles(host: TestServerHost, expectedFiles: string[], additionalInfo?: string) {
+        checkMapKeys(`watchedFiles:: ${additionalInfo || ""}::`, host.watchedFiles, expectedFiles);
     }
 
     export function checkWatchedFilesDetailed(host: TestServerHost, expectedFiles: ReadonlyMap<number>): void;

src/testRunner/unittests/tsserver/helpers.ts

@@ -488,8 +488,8 @@ namespace ts.projectSystem {
         checkArray("Open files", arrayFrom(projectService.openFiles.keys(), path => projectService.getScriptInfoForPath(path as Path)!.fileName), expectedFiles.map(file => file.path));
     }
 
-    export function checkScriptInfos(projectService: server.ProjectService, expectedFiles: ReadonlyArray<string>) {
-        checkArray("ScriptInfos files", arrayFrom(projectService.filenameToScriptInfo.values(), info => info.fileName), expectedFiles);
+    export function checkScriptInfos(projectService: server.ProjectService, expectedFiles: ReadonlyArray<string>, additionInfo?: string) {
+        checkArray(`ScriptInfos files: ${additionInfo || ""}`, arrayFrom(projectService.filenameToScriptInfo.values(), info => info.fileName), expectedFiles);
     }
 
     export function protocolLocationFromSubstring(str: string, substring: string): protocol.Location {