[TypeSpec Validation] Ensure "compile" and "format" rules fail if process returns error (#25458)

- Fixes #25453

Author: ckairen

eng/tools/TypeSpecValidation/src/rules/compile.ts

@@ -13,23 +13,25 @@ export class CompileRule implements Rule {
     let errorOutput: string | undefined;
 
     if (await checkFileExists(path.join(folder, "main.tsp"))) {
-      let [std, err] = await runCmd(`npx --no tsp compile . --warn-as-error`, folder);
-      stdOutput += std;
-      if (err == null) {
+      let [err, stdout, stderr] = await runCmd(`npx --no tsp compile . --warn-as-error`, folder);
+      if (err) {
         success = false;
-        errorOutput += err;
+        errorOutput += err.message;
       }
+      stdOutput += stdout;
+      errorOutput += stderr;
     }
     if (await checkFileExists(path.join(folder, "client.tsp"))) {
-      let [std, err] = await runCmd(
+      let [err, stdout, stderr] = await runCmd(
         `npx --no tsp compile client.tsp --no-emit --warn-as-error`,
         folder
       );
-      stdOutput += std;
-      if (err == null) {
+      if (err) {
         success = false;
-        errorOutput += err;
+        errorOutput += err.message;
       }
+      stdOutput += stdout;
+      errorOutput += stderr;
     }
 
     return {

eng/tools/TypeSpecValidation/src/rules/format.ts

@@ -8,9 +8,11 @@ export class FormatRule implements Rule {
 
   async execute(folder: string): Promise<RuleResult> {
     // Format parent folder to include shared files
-    let [stdOutput, errorOutput] = await runCmd(`npx tsp format ../**/*.tsp`, folder);
 
-    let success = errorOutput == null ? false : true;
+    let [err, stdOutput, errorOutput] = await runCmd(`npx tsp format ../**/*.tsp`, folder);
+    // Failing on both err and errorOutput because of known bug in tsp format where it returns 0 on failed formatting
+    // https://github.com/microsoft/typespec/issues/2323
+    let success = !err && !errorOutput;
     return {
       success: success,
       stdOutput: stdOutput,

eng/tools/TypeSpecValidation/src/rules/npm-prefix.ts

@@ -8,7 +8,7 @@ export class NpmPrefixRule implements Rule {
 
   async execute(folder: string): Promise<RuleResult> {
     let expected_npm_prefix = process.cwd();
-    const actual_npm_prefix = (await runCmd(`npm prefix`, folder))[0].trim();
+    const actual_npm_prefix = (await runCmd(`npm prefix`, folder))[1].trim();
 
     let success = true;
     let stdOutput =

eng/tools/TypeSpecValidation/src/utils.ts

@@ -12,7 +12,7 @@ export async function runCmd(cmd: string, cwd: string) {
     )
   )) as any;
 
-  return [stdout, stderr + err?.message] as string[];
+  return [err, stdout, stderr];
 }
 
 export async function checkFileExists(file: string) {