fixCannotFindModule: Special handling for node core modules like "fs" (microsoft#23807)

* fixCannotFindModule: Special handling for node core modules like "fs"

* Hardcode @types/node

Author: Andy

src/services/codefixes/fixCannotFindModule.ts

@@ -1,18 +1,22 @@
 /* @internal */
 namespace ts.codefix {
     const fixId = "fixCannotFindModule";
-    const errorCodes = [Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type.code];
+    const errorCodeCannotFindModule = Diagnostics.Cannot_find_module_0.code;
+    const errorCodes = [
+        errorCodeCannotFindModule,
+        Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type.code,
+    ];
     registerCodeFix({
         errorCodes,
         getCodeActions: context => {
             const { host, sourceFile, span: { start } } = context;
-            const packageName = getTypesPackageNameToInstall(host, sourceFile, start);
+            const packageName = getTypesPackageNameToInstall(host, sourceFile, start, context.errorCode);
             return packageName === undefined ? []
                 : [createCodeFixAction(fixId, /*changes*/ [], [Diagnostics.Install_0, packageName], fixId, Diagnostics.Install_all_missing_types_packages, getCommand(sourceFile.fileName, packageName))];
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (_, diag, commands) => {
-            const pkg = getTypesPackageNameToInstall(context.host, diag.file, diag.start);
+            const pkg = getTypesPackageNameToInstall(context.host, diag.file, diag.start, diag.code);
             if (pkg) {
                 commands.push(getCommand(diag.file.fileName, pkg));
             }
@@ -23,9 +27,11 @@ namespace ts.codefix {
         return { type: "install package", file: fileName, packageName };
     }
 
-    function getTypesPackageNameToInstall(host: LanguageServiceHost, sourceFile: SourceFile, pos: number): string | undefined {
+    function getTypesPackageNameToInstall(host: LanguageServiceHost, sourceFile: SourceFile, pos: number, diagCode: number): string | undefined {
         const moduleName = cast(getTokenAtPosition(sourceFile, pos, /*includeJsDocComment*/ false), isStringLiteral).text;
         const { packageName } = getPackageName(moduleName);
-        return host.isKnownTypesPackageName(packageName) ? getTypesPackageName(packageName) : undefined;
+        return diagCode === errorCodeCannotFindModule
+            ? (JsTyping.nodeCoreModules.has(packageName) ? "@types/node" : undefined)
+            : (host.isKnownTypesPackageName(packageName) ? getTypesPackageName(packageName) : undefined);
     }
 }

src/services/jsTyping.ts

@@ -39,7 +39,8 @@ namespace ts.JsTyping {
         "crypto", "stream", "util", "assert", "tty", "domain",
         "constants", "process", "v8", "timers", "console"];
 
-    const nodeCoreModules = arrayToSet(nodeCoreModuleList);
+    /* @internal */
+    export const nodeCoreModules = arrayToSet(nodeCoreModuleList);
 
     /**
      * A map of loose file names to library names that we are confident require typings

tests/cases/fourslash/codeFixCannotFindModule_nodeCoreModules.ts

@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts' />
+
+// @noImplicitAny: true
+
+// @Filename: /a.ts
+////import fs = require("fs");
+////fs;
+
+verify.codeFixAvailable([{
+    description: "Install '@types/node'",
+    commands: [{
+        type: "install package",
+        file: "/a.ts",
+        packageName: "@types/node",
+    }],
+}]);