[TypeSpec Validation] Improve error for incorrect argument

eng/tools/typespec-validation/src/index.ts

@@ -21,6 +21,14 @@ export async function main() {
   const folder = parsedArgs.positionals[0];
   const absolutePath = host.normalizePath(folder);
 
+  if (!(await host.checkFileExists(absolutePath))) {
+    console.log(`Folder ${absolutePath} does not exist`);
+    process.exit(1);
+  }
+  if (!(await host.isDirectory(absolutePath))) {
+    console.log(`Please run TypeSpec Validation on a directory path`);
+    process.exit(1);
+  }
   console.log("Running TypeSpecValidation on folder: ", absolutePath);
 
   const rules = [

eng/tools/typespec-validation/src/tsv-host.ts

@@ -1,5 +1,6 @@
 export interface TsvHost {
   checkFileExists(file: string): Promise<boolean>;
+  isDirectory(path: string): Promise<boolean>;
   gitOperation(folder: string): IGitOperation;
   readTspConfig(folder: string): Promise<string>;
   runCmd(cmd: string, cwd: string): Promise<[Error | null, string, string]>;

eng/tools/typespec-validation/src/tsv-runner-host.ts

@@ -3,13 +3,17 @@ import { readFile } from "fs/promises";
 import { IGitOperation, TsvHost } from "./tsv-host.js";
 import { globby } from "globby";
 import { simpleGit } from "simple-git";
-import { checkFileExists, normalizePath, runCmd } from "./utils.js";
+import { checkFileExists, isDirectory, normalizePath, runCmd } from "./utils.js";
 
 export class TsvRunnerHost implements TsvHost {
   checkFileExists(file: string): Promise<boolean> {
     return checkFileExists(file);
   }
 
+  isDirectory(path: string) {
+    return isDirectory(path);
+  }
+
   gitOperation(folder: string): IGitOperation {
     return simpleGit(folder);
   }

eng/tools/typespec-validation/src/utils.ts

@@ -1,4 +1,4 @@
-import { access } from "fs/promises";
+import { access, stat } from "fs/promises";
 import { exec } from "child_process";
 import defaultPath, { PlatformPath } from "path";
 
@@ -22,6 +22,10 @@ export async function checkFileExists(file: string) {
     .catch(() => false);
 }
 
+export async function isDirectory(path: string) {
+  return (await stat(path)).isDirectory();
+}
+
 export function normalizePath(folder: string, path: PlatformPath = defaultPath) {
   return path
     .resolve(folder)

eng/tools/typespec-validation/test/tsv-test-host.ts

@@ -44,6 +44,10 @@ export class TsvTestHost implements TsvHost {
     return true;
   }
 
+  async isDirectory(_path: string): Promise<boolean> {
+    return true;
+  }
+
   normalizePath(folder: string): string {
     return normalizePath(folder, this.path);
   }