Everything builds and tests pass

Except for the new test I added.

src/server/editorServices.ts

@@ -3693,33 +3693,33 @@ namespace ts.server {
             // ugggggggggg have to copy over all that stuff to here
             // (though I probably need to create a vfs project anyway, so why not)
             
-            const fs = new vfs.FileSystem(/*ignoreCase*/ true, {
-                files: {
-                    [builtFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "built/local"), resolver),
-                    [testLibFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "tests/lib"), resolver),
-                    [projectsFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "tests/projects"), resolver),
-                    [srcFolder]: {}
-                },
-                cwd: srcFolder,
-                meta: { defaultLibLocation: builtFolder }
-            })
-            if (!this.fs)
-                this.fs = fs
-            if (createdFiles) {
-                for (const document of Array.from(createdFiles)) {
-                    fs.mkdirpSync(vpath.dirname(document.file));
-                    fs.writeFileSync(document.file, document.text, "utf8");
-                    fs.filemeta(document.file).set("document", document);
-                    // Add symlinks
-                    const symlink = document.meta.get("symlink");
-                    if (symlink) {
-                        for (const link of symlink.split(",").map(link => link.trim())) {
-                            fs.mkdirpSync(vpath.dirname(link));
-                            fs.symlinkSync(vpath.resolve(fs.cwd(), document.file), link);
-                        }
-                    }
-                }
-            }
+            // const fs = new vfs.FileSystem(/*ignoreCase*/ true, {
+            //     files: {
+            //         [builtFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "built/local"), resolver),
+            //         [testLibFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "tests/lib"), resolver),
+            //         [projectsFolder]: new Mount(vpath.resolve(host.getWorkspaceRoot(), "tests/projects"), resolver),
+            //         [srcFolder]: {}
+            //     },
+            //     cwd: srcFolder,
+            //     meta: { defaultLibLocation: builtFolder }
+            // })
+            // if (!this.fs)
+            //     this.fs = fs
+            // if (createdFiles) {
+            //     for (const document of Array.from(createdFiles)) {
+            //         fs.mkdirpSync(vpath.dirname(document.file));
+            //         fs.writeFileSync(document.file, document.text, "utf8");
+            //         fs.filemeta(document.file).set("document", document);
+            //         // Add symlinks
+            //         const symlink = document.meta.get("symlink");
+            //         if (symlink) {
+            //             for (const link of symlink.split(",").map(link => link.trim())) {
+            //                 fs.mkdirpSync(vpath.dirname(link));
+            //                 fs.symlinkSync(vpath.resolve(fs.cwd(), document.file), link);
+            //             }
+            //         }
+            //     }
+            // }
 
             // 1. set some internal tsserver state for mocked FS (if it hasn't already been set, this might not be the first message)
             //   - change this.host at least

src/testRunner/tsconfig.json

@@ -22,6 +22,7 @@
         { "path": "../server", "prepend": true },
         { "path": "../webServer", "prepend": true },
         { "path": "../typingsInstallerCore", "prepend": true },
+        { "path": "../vfs", "prepend": true },
         { "path": "../harness", "prepend": true },
         { "path": "../loggedIO", "prepend": true }
     ],

src/vfs/vfsUtil.ts

@@ -1598,23 +1598,4 @@ namespace vfs {
         }
         return text;
     }
-
-    export function iteratePatch(patch: FileSet | undefined): IterableIterator<[string, string]> | null {
-        // eslint-disable-next-line no-null/no-null
-        return patch ? Harness.Compiler.iterateOutputs(iteratePatchWorker("", patch)) : null;
-    }
-
-    function* iteratePatchWorker(dirname: string, container: FileSet): IterableIterator<documents.TextDocument> {
-        for (const name of Object.keys(container)) {
-            const entry = normalizeFileSetEntry(container[name]);
-            const file = dirname ? vpath.combine(dirname, name) : name;
-            if (entry instanceof Directory) {
-                yield* ts.arrayFrom(iteratePatchWorker(file, entry.files));
-            }
-            else if (entry instanceof File) {
-                const content = typeof entry.data === "string" ? entry.data : entry.data.toString("utf8");
-                yield new documents.TextDocument(file, content);
-            }
-        }
-    }
 }

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -6970,6 +6970,7 @@ declare namespace ts.server.protocol {
         OpenExternalProjects = "openExternalProjects",
         CloseExternalProject = "closeExternalProject",
         UpdateOpen = "updateOpen",
+        UpdateFileSystem = "updateFileSystem",
         GetOutliningSpans = "getOutliningSpans",
         TodoComments = "todoComments",
         Indentation = "indentation",
@@ -8216,6 +8217,7 @@ declare namespace ts.server.protocol {
     }
     /**
      * Request to synchronize list of open files with the client
+     * TODO: Lots of unit tests refer to this too, a good starting point for UpdateFileSystemRequest
      */
     interface UpdateOpenRequest extends Request {
         command: CommandTypes.UpdateOpen;
@@ -8230,7 +8232,7 @@ declare namespace ts.server.protocol {
          */
         openFiles?: OpenRequestArgs[];
         /**
-         * List of open files files that were changes
+         * List of open files files that were changed
          */
         changedFiles?: FileCodeEdits[];
         /**
@@ -8238,6 +8240,33 @@ declare namespace ts.server.protocol {
          */
         closedFiles?: string[];
     }
+    interface UpdateFileSystemRequest extends Request {
+        command: CommandTypes.UpdateFileSystem;
+        arguments: UpdateFileSystemRequestArgs;
+    }
+    interface UpdateFileSystemRequestArgs {
+        /** For now, only 'memfs', initially for exclusive in-memory operation, but it could be other in-memory names later */
+        fileSystem: string;
+        /** For now, a list of newly created or newly available files. Probably need to ADD mocked file watchers */
+        created: FileSystemRequestArgs[];
+        /** Just-deleted files. Also needs to trigger and then remove file watchers (I think) */
+        deleted: string[];
+        /** Needs to replace what file watchers would normally listen to */
+        updated: FileSystemRequestArgs[];
+    }
+    interface FileSystemRequestArgs extends FileRequestArgs {
+        /**
+         * Used to replace the content that would be on disk.
+         * Then the known content will be used upon opening instead of the disk copy
+         */
+        fileContent?: string;
+        /**
+         * Used to specify the script kind of the file explicitly. It could be one of the following:
+         *      "TS", "JS", "TSX", "JSX"
+         * TODO: Not 100% sure this is needed.
+         */
+        scriptKindName?: ScriptKindName;
+    }
     /**
      * External projects have a typeAcquisition option so they need to be added separately to compiler options for inferred projects.
      */