fix(@angular/cli): error when updating Angular packages across multi-major migrations

With this change we show an error message when users try to update `@angular/` and `@nguniversal/` packages across multiple major versions.

(cherry picked from commit d60d374)

Author: alan-agius4

packages/angular/cli/commands/update-impl.ts

@@ -623,6 +623,35 @@ export class UpdateCommand extends Command<UpdateCommandSchema> {
         continue;
       }
 
+      if (node.package && /^@(?:angular|nguniversal)\//.test(node.package.name)) {
+        const { name, version } = node.package;
+        const toBeInstalledMajorVersion = +manifest.version.split('.')[0];
+        const currentMajorVersion = +version.split('.')[0];
+
+        if (toBeInstalledMajorVersion - currentMajorVersion > 1) {
+          // Only allow updating a single version at a time.
+          if (currentMajorVersion < 6) {
+            // Before version 6, the major versions were not always sequential.
+            // Example @angular/core skipped version 3, @angular/cli skipped versions 2-5.
+            this.logger.error(
+              `Updating multiple major versions of '${name}' at once is not supported. Please migrate each major version individually.\n` +
+                `For more information about the update process, see https://update.angular.io/.`,
+            );
+          } else {
+            const nextMajorVersionFromCurrent = currentMajorVersion + 1;
+
+            this.logger.error(
+              `Updating multiple major versions of '${name}' at once is not supported. Please migrate each major version individually.\n` +
+                `Run 'ng update ${name}@${nextMajorVersionFromCurrent}' in your workspace directory ` +
+                `to update to latest '${nextMajorVersionFromCurrent}.x' version of '${name}'.\n\n` +
+                `For more information about the update process, see https://update.angular.io/?v=${currentMajorVersion}.0-${nextMajorVersionFromCurrent}.0`,
+            );
+          }
+
+          return 1;
+        }
+      }
+
       packagesToUpdate.push(requestIdentifier.toString());
     }
 

tests/legacy-cli/e2e/tests/update/update-multiple-versions.ts

@@ -0,0 +1,35 @@
+import { createProjectFromAsset } from '../../utils/assets';
+import { installWorkspacePackages, setRegistry } from '../../utils/packages';
+import { ng } from '../../utils/process';
+import { isPrereleaseCli } from '../../utils/project';
+import { expectToFail } from '../../utils/utils';
+
+export default async function () {
+  try {
+    await createProjectFromAsset('8.0-project', true, true);
+    await setRegistry(false);
+    await installWorkspacePackages();
+
+    await setRegistry(true);
+    const extraArgs = ['--force'];
+    if (isPrereleaseCli()) {
+      extraArgs.push('--next');
+    }
+
+    const { message } = await expectToFail(() =>
+      ng('update', '@angular/cli', '--force', ...extraArgs),
+    );
+    if (
+      !message.includes(
+        `Updating multiple major versions of '@angular/cli' at once is not supported`,
+      )
+    ) {
+      console.error(message);
+      throw new Error(
+        `Expected error message to include "Updating multiple major versions of '@angular/cli' at once is not supported" but didn't.`,
+      );
+    }
+  } finally {
+    await setRegistry(true);
+  }
+}