fix(scripts-lint-staged): dont fail lint process if it contains only …

…severity 'warn' violations and improve output format (microsoft#30173)

scripts/lint-staged/eslint-for-package.js

@@ -1,10 +1,11 @@
 // @ts-check
 
 const path = require('path');
+
+const { eslintConstants } = require('@fluentui/scripts-monorepo');
 const { ESLint } = require('eslint');
 const fs = require('fs-extra');
 const micromatch = require('micromatch');
-const { eslintConstants } = require('@fluentui/scripts-monorepo');
 
 /**
  * Run ESLint for certain files from a particular package.
@@ -57,19 +58,30 @@ async function run() {
 
   // Lint files then fix all auto-fixable issues
   const results = await eslint.lintFiles(filteredFiles);
+  const hasSeverityError = results.some(lintResult => lintResult.errorCount > 0);
 
   await ESLint.outputFixes(results);
 
   // Format results
   const formatter = await eslint.loadFormatter();
   const resultText = formatter.format(results);
-  if (resultText) {
-    throw new Error(resultText);
+
+  if (!resultText) {
+    return;
   }
+
+  if (!hasSeverityError) {
+    // print lint output warnings
+    // - logging is handled by ./eslint.js. you'll see this output only if you directly call this script
+    console.log(resultText);
+    return;
+  }
+
+  // this error throw will be processed by parent process (./eslint.js)
+  // print lint errors ( and warnings if present )
+  throw new Error(resultText);
 }
 
 run().catch(err => {
-  // logging is handled by ./eslint.js. If you wanna directly call this script and see errors uncomment following line ↓
-  // console.error(err);
   throw new Error(err);
 });

scripts/lint-staged/eslint.js

@@ -10,6 +10,9 @@ const { rollup: lernaAliases } = require('lerna-alias');
 const { default: PQueue } = require('p-queue');
 const exec = promisify(child_process.exec);
 
+/**
+ * @see file://./eslint-for-package.js
+ */
 const eslintForPackageScript = path.join(__dirname, 'eslint-for-package.js');
 
 const files = process.argv.slice(2);
@@ -69,20 +72,26 @@ async function runEslintOnFilesGroupedPerPackage() {
   await queue.addAll(
     // eslint-disable-next-line no-shadow
     Object.entries(filesGroupedByPackage).map(([packagePath, files]) => async () => {
+      // This script handles running eslint on ONLY touched files for each package.
       const cmd = `node ${eslintForPackageScript} ${files.join(' ')}`;
 
-      // This script handles running eslint on ONLY the appropriate files for each package.
-      // See its comments for more details.
-      return exec(cmd, { cwd: packagePath }).catch((/** @type {{ stdout: string, stderr: string }} */ err) => {
-        // The subprocess should already have handled logging. Just mark that there was an error.
-        hasError = true;
-        throw new Error(err.stderr);
-      });
+      return (
+        exec(cmd, { cwd: packagePath })
+          // Log severity:error lint reports including severity:warn
+          // this will also result in killing the process
+          .catch((/** @type {{ stdout: string, stderr: string }} */ err) => {
+            hasError = true;
+            // child throws twice so to mitigate `Error: Error: ` output we remove the 1st one
+            const report = err.stderr.replace('Error: ', '');
+            console.error(report);
+          })
+      );
     }),
   );
 
   await queue
     .onEmpty()
+    // handle any internal exec errors
     .catch(error => {
       console.error(error);
       hasError = true;
@@ -94,7 +103,11 @@ async function runEslintOnFilesGroupedPerPackage() {
     });
 }
 
-runEslintOnFilesGroupedPerPackage().catch(err => {
-  console.error(err);
-  process.exit(1);
-});
+function main() {
+  runEslintOnFilesGroupedPerPackage().catch(err => {
+    console.error(err);
+    process.exit(1);
+  });
+}
+
+main();