Add test case to verify correct resolution file is picked when current resolution file is not removed but higher precedence file is created

Author: sheetalkamat

src/compiler/program.ts

@@ -825,7 +825,7 @@ namespace ts {
                 const moduleName = moduleNames[i];
                 // If we want to reuse resolutions more aggressively, we can refine this to check for whether the
                 // text of the corresponding modulenames has changed.
-                if (file === oldSourceFile) {
+                if (file === oldSourceFile && !hasInvalidatedResolution(oldSourceFile.path)) {
                     const oldResolvedModule = oldSourceFile && oldSourceFile.resolvedModules.get(moduleName);
                     if (oldResolvedModule) {
                         if (isTraceEnabled(options, host)) {
@@ -846,7 +846,7 @@ namespace ts {
                         trace(host, Diagnostics.Module_0_was_resolved_as_locally_declared_ambient_module_in_file_1, moduleName, containingFile);
                     }
                 }
-                else if (!hasInvalidatedResolution(oldProgramState.file.path)) {
+                else {
                     resolvesToAmbientModuleInNonModifiedFile = moduleNameResolvesToAmbientModuleInNonModifiedFile(moduleName, oldProgramState);
                 }
 

src/harness/unittests/tsserverProjectSystem.ts

@@ -2306,6 +2306,59 @@ namespace ts.projectSystem {
             });
             assert.isFalse(hasErrorMsg);
         });
+
+        it("Changed module resolution reflected when specifying files list", () => {
+            const file1: FileOrFolder = {
+                path: "/a/b/file1.ts",
+                content: 'import classc from "file2"'
+            };
+            const file2a: FileOrFolder = {
+                path: "/a/file2.ts",
+                content: "export classc { method2a() { return 10; } }"
+            };
+            const file2: FileOrFolder = {
+                path: "/a/b/file2.ts",
+                content: "export classc { method2() { return 10; } }"
+            };
+            const configFile: FileOrFolder = {
+                path: "/a/b/tsconfig.json",
+                content: JSON.stringify({ files: [file1.path], compilerOptions: { module: "amd" } })
+            };
+            const files = [file1, file2a, configFile, libFile];
+            const host = createServerHost(files);
+            const projectService = createProjectService(host);
+            projectService.openClientFile(file1.path);
+            checkNumberOfProjects(projectService, { configuredProjects: 1 });
+            const project = projectService.configuredProjects.get(configFile.path);
+            assert.isDefined(project);
+            checkProjectActualFiles(project, map(files, file => file.path));
+            checkWatchedFiles(host, mapDefined(files, file => file === file1 ? undefined : file.path));
+            checkWatchedDirectories(host, [], /*recursive*/ false);
+            const watchedRecursiveDirectories = getTypeRootsFromLocation("/a/b");
+            watchedRecursiveDirectories.push("/a/b");
+            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
+
+            files.push(file2);
+            host.reloadFS(files);
+            host.runQueuedTimeoutCallbacks();
+            watchedRecursiveDirectories.pop();
+            checkNumberOfProjects(projectService, { configuredProjects: 1 });
+            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
+            checkProjectActualFiles(project, mapDefined(files, file => file === file2a ? undefined : file.path));
+            checkWatchedFiles(host, mapDefined(files, file => file === file1 ? undefined : file.path));
+            checkWatchedDirectories(host, [], /*recursive*/ false);
+            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
+
+            // On next file open the files file2a should be closed and not watched any more
+            projectService.openClientFile(file2.path);
+            checkNumberOfProjects(projectService, { configuredProjects: 1 });
+            assert.strictEqual(projectService.configuredProjects.get(configFile.path), project);
+            checkProjectActualFiles(project, mapDefined(files, file => file === file2a ? undefined : file.path));
+            checkWatchedFiles(host, [libFile.path, configFile.path]);
+            checkWatchedDirectories(host, [], /*recursive*/ false);
+            checkWatchedDirectories(host, watchedRecursiveDirectories, /*recursive*/ true);
+
+        });
     });
 
     describe("Proper errors", () => {

src/harness/virtualFileSystemWithWatch.ts

@@ -130,9 +130,9 @@ namespace ts.TestFSWithWatch {
     }
 
     export function checkFileNames(caption: string, actualFileNames: string[], expectedFileNames: string[]) {
-        assert.equal(actualFileNames.length, expectedFileNames.length, `${caption}: incorrect actual number of files, expected ${JSON.stringify(expectedFileNames)}, got ${actualFileNames}`);
+        assert.equal(actualFileNames.length, expectedFileNames.length, `${caption}: incorrect actual number of files, expected ${expectedFileNames}, got ${actualFileNames}`);
         for (const f of expectedFileNames) {
-            assert.isTrue(contains(actualFileNames, f), `${caption}: expected to find ${f} in ${JSON.stringify(actualFileNames)}`);
+            assert.isTrue(contains(actualFileNames, f), `${caption}: expected to find ${f} in ${actualFileNames}`);
         }
     }