diff --git a/packages/cli/test/snapshot-matcher.js b/packages/cli/test/snapshot-matcher.js
index cfa4d567b700..65167eb1960c 100644
--- a/packages/cli/test/snapshot-matcher.js
+++ b/packages/cli/test/snapshot-matcher.js
@@ -14,6 +14,7 @@ This is an initial experimental version. In the (near) future, we should
 move this file to a standalone package so that all Mocha users can use it.
 */
 
+const chalk = require('chalk');
 const assert = require('assert');
 const path = require('path');
 
@@ -43,6 +44,7 @@ module.exports = {
  */
 function initializeSnapshots(snapshotDir) {
   let currentTest;
+  let snapshotErrors = false;
 
   beforeEach(function setupSnapshots() {
     // eslint-disable-next-line no-invalid-this
@@ -51,17 +53,34 @@ function initializeSnapshots(snapshotDir) {
   });
 
   if (!process.env.UPDATE_SNAPSHOTS) {
+    process.on('exit', function printSnapshotHelp() {
+      if (!snapshotErrors) return;
+      console.log(
+        chalk.red(`
+Some of the snapshot-based tests have failed. Please carefully inspect
+the differences to prevent possible regressions. If the changes are
+intentional, run the tests again with \`UPDATE_SNAPSHOTS=1\` environment
+variable to update snapshots.
+        `),
+      );
+    });
     return function expectToMatchSnapshot(actual) {
-      matchSnapshot(snapshotDir, currentTest, actual);
+      try {
+        matchSnapshot(snapshotDir, currentTest, actual);
+      } catch (err) {
+        snapshotErrors = true;
+        throw err;
+      }
     };
   }
 
   const snapshots = Object.create(null);
-  after(function updateSnapshots() {
-    for (const f in snapshots) {
+  after(async function updateSnapshots() {
+    const tasks = Object.entries(snapshots).map(([f, data]) => {
       const snapshotFile = buildSnapshotFilePath(snapshotDir, f);
-      writeSnapshotData(snapshotFile, snapshots[f]);
-    }
+      return writeSnapshotData(snapshotFile, data);
+    });
+    await Promise.all(tasks);
   });
 
   return function expectToRecordSnapshot(actual) {
@@ -83,7 +102,7 @@ function matchSnapshot(snapshotDir, currentTest, actualValue) {
   if (!(key in snapshotData)) {
     throw new Error(
       `No snapshot found for ${JSON.stringify(key)}.\n` +
-        'Run the tests with UPDATE_SNAPSHOTS=1 in the environment ' +
+        'Run the tests with `UPDATE_SNAPSHOTS=1` environment variable ' +
         'to create and update snapshot files.',
     );
   }
@@ -153,7 +172,7 @@ function loadSnapshotData(snapshotFile) {
     if (err.code === 'MODULE_NOT_FOUND') {
       throw new Error(
         `Snapshot file ${snapshotFile} was not found.\n` +
-          'Run the tests with UPDATE_SNAPSHOTS=1 in the environment ' +
+          'Run the tests with `UPDATE_SNAPSHOTS=1` environment variable ' +
           'to create and update snapshot files.',
       );
     }
@@ -182,7 +201,7 @@ function writeSnapshotData(snapshotFile, snapshots) {
 
   const content = header + entries.join('\n');
   mkdirp.sync(path.dirname(snapshotFile));
-  writeFileAtomic.sync(snapshotFile, content, {encoding: 'utf-8'});
+  return writeFileAtomic(snapshotFile, content, {encoding: 'utf-8'});
 }
 
 function buildSnapshotCode(key, value) {