remove projects that were no present in the input list in openExternalProjects

src/harness/unittests/tsserverProjectSystem.ts

@@ -727,6 +727,66 @@ namespace ts.projectSystem {
             checkNumberOfInferredProjects(projectService, 1);
         });
 
+        it("remove not-listed external projects", () => {
+            const f1 = {
+                path: "/a/app.ts",
+                content: "let x = 1"
+            };
+            const f2 = {
+                path: "/b/app.ts",
+                content: "let x = 1"
+            };
+            const f3 = {
+                path: "/c/app.ts",
+                content: "let x = 1"
+            };
+            const makeProject = (f:  FileOrFolder) => ({ projectFileName: f.path + ".csproj", rootFiles: [toExternalFile(f.path)], options: {} });
+            const p1 = makeProject(f1);
+            const p2 = makeProject(f2);
+            const p3 = makeProject(f3);
+
+            const host = createServerHost([f1, f2, f3]);
+            const session = createSession(host);
+
+            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
+                seq: 1,
+                type: "request",
+                command: "openExternalProjects",
+                arguments: { projects: [p1, p2] }
+            });
+
+            const projectService = session.getProjectService();
+            checkNumberOfProjects(projectService, { externalProjects: 2 });
+            assert.equal(projectService.externalProjects[0].getProjectName(), p1.projectFileName);
+            assert.equal(projectService.externalProjects[1].getProjectName(), p2.projectFileName);
+
+            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
+                seq: 2,
+                type: "request",
+                command: "openExternalProjects",
+                arguments: { projects: [p1, p3] }
+            });
+            checkNumberOfProjects(projectService, { externalProjects: 2 });
+            assert.equal(projectService.externalProjects[0].getProjectName(), p1.projectFileName);
+            assert.equal(projectService.externalProjects[1].getProjectName(), p3.projectFileName);
+
+            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
+                seq: 3,
+                type: "request",
+                command: "openExternalProjects",
+                arguments: { projects: [] }
+            });
+            checkNumberOfProjects(projectService, { externalProjects: 0 });
+
+            session.executeCommand(<protocol.OpenExternalProjectsRequest>{
+                seq: 3,
+                type: "request",
+                command: "openExternalProjects",
+                arguments: { projects: [p2] }
+            });
+            assert.equal(projectService.externalProjects[0].getProjectName(), p2.projectFileName);
+        });
+
         it("handle recreated files correctly", () => {
             const configFile: FileOrFolder = {
                 path: "/a/b/tsconfig.json",

src/server/editorServices.ts

@@ -1327,7 +1327,28 @@ namespace ts.server {
             }
         }
 
-        openExternalProject(proj: protocol.ExternalProject): void {
+        openExternalProjects(projects: protocol.ExternalProject[]): void {
+            // record project list before the update
+            const projectsToClose =  arrayToMap(this.externalProjects, p => p.getProjectName(), _ => true);
+            for (const externalProjectName in this.externalProjectToConfiguredProjectMap) {
+                projectsToClose[externalProjectName] = true;
+            }
+
+            for (const externalProject of projects) {
+                this.openExternalProject(externalProject, /*suppressRefreshOfInferredProjects*/ true);
+                // delete project that is present in input list
+                delete projectsToClose[externalProject.projectFileName];
+            }
+
+            // close projects that were missing in the input list
+            for (const externalProjectName in projectsToClose) {
+                this.closeExternalProject(externalProjectName, /*suppressRefresh*/ true)
+            }
+
+            this.refreshInferredProjects();
+        }
+
+        openExternalProject(proj: protocol.ExternalProject, suppressRefreshOfInferredProjects = false): void {
             // typingOptions has been deprecated and is only supported for backward compatibility
             // purposes. It should be removed in future releases - use typeAcquisition instead.
             if (proj.typingOptions && !proj.typeAcquisition) {
@@ -1420,7 +1441,9 @@ namespace ts.server {
                 delete this.externalProjectToConfiguredProjectMap[proj.projectFileName];
                 this.createAndAddExternalProject(proj.projectFileName, rootFiles, proj.options, proj.typeAcquisition);
             }
-            this.refreshInferredProjects();
+            if (!suppressRefreshOfInferredProjects) {
+                this.refreshInferredProjects();
+            }
         }
     }
 }

src/server/session.ts

@@ -1365,14 +1365,12 @@ namespace ts.server {
 
         private handlers = createMap<(request: protocol.Request) => { response?: any, responseRequired?: boolean }>({
             [CommandNames.OpenExternalProject]: (request: protocol.OpenExternalProjectRequest) => {
-                this.projectService.openExternalProject(request.arguments);
+                this.projectService.openExternalProject(request.arguments, /*suppressRefreshOfInferredProjects*/ false);
                 // TODO: report errors
                 return this.requiredResponse(true);
             },
             [CommandNames.OpenExternalProjects]: (request: protocol.OpenExternalProjectsRequest) => {
-                for (const proj of request.arguments.projects) {
-                    this.projectService.openExternalProject(proj);
-                }
+                this.projectService.openExternalProjects(request.arguments.projects);
                 // TODO: report errors
                 return this.requiredResponse(true);
             },