cli: create writeFile destination if necessary (#15990)

cli/printer.js

@@ -5,6 +5,7 @@
  */
 
 import fs from 'fs';
+import path from 'path';
 
 import log from 'lighthouse-logger';
 
@@ -58,13 +59,17 @@ function writeToStdout(output) {
  */
 function writeFile(filePath, output, outputMode) {
   return new Promise((resolve, reject) => {
-    // TODO: make this mkdir to the filePath.
-    fs.writeFile(filePath, output, (err) => {
-      if (err) {
+    fs.mkdir(path.dirname(filePath), {recursive: true}, (err) => {
+      if (err && err.code !== 'EEXIST') {
         return reject(err);
       }
-      log.log('Printer', `${OutputMode[outputMode]} output written to ${filePath}`);
-      resolve();
+      fs.writeFile(filePath, output, (err) => {
+        if (err) {
+          return reject(err);
+        }
+        log.log('Printer', `${OutputMode[outputMode]} output written to ${filePath}`);
+        resolve();
+      });
     });
   });
 }

cli/test/cli/printer-test.js

@@ -6,6 +6,7 @@
 
 import assert from 'assert/strict';
 import fs from 'fs';
+import path from 'path';
 
 import {readJson} from '../../../core/test/test-utils.js';
 import * as Printer from '../../printer.js';
@@ -34,11 +35,9 @@ describe('Printer', () => {
   });
 
   it('throws for invalid paths', () => {
-    const path = '!/#@.json';
+    const path = '//#@.json';
     const report = JSON.stringify(sampleResults);
-    return Printer.write(report, 'html', path).catch(err => {
-      assert.ok(err.code === 'ENOENT');
-    });
+    return assert.rejects(Printer.write(report, 'html', path));
   });
 
   it('returns output modes', () => {
@@ -49,4 +48,20 @@ describe('Printer', () => {
       assert.strictEqual(typeof mode, 'string');
     });
   });
+
+  it('creates missing directories when writing to file', () => {
+    const dirPath = './non/existent/directory/.test-file.json';
+    const report = JSON.stringify(sampleResults);
+    const dir = path.dirname(dirPath);
+    if (fs.existsSync(dir)) {
+      fs.rmdirSync(dir, {recursive: true});
+    }
+    return Printer.write(report, 'json', dirPath).then(_ => {
+      assert.ok(fs.existsSync(dir), `Directory ${dir} should exist now`);
+      const fileContents = fs.readFileSync(dirPath, 'utf8');
+      assert.ok(/lighthouseVersion/gim.test(fileContents));
+      fs.unlinkSync(dirPath);
+      fs.rmdirSync(dir, {recursive: true});
+    });
+  });
 });