feat(@schematics/angular): default interface for guard

Currently, if the user hits `<Enter>` before selecting an interface to implement, the CLI generates a broken guard that implements no interface. With this commit, the CLI generates a `CanActivate` guard by default.

Author: cexbrayat

packages/schematics/angular/guard/index.ts

@@ -8,7 +8,6 @@
 import { strings } from '@angular-devkit/core';
 import {
   Rule,
-  SchematicsException,
   Tree,
   apply,
   applyTemplates,
@@ -37,13 +36,14 @@ export default function (options: GuardOptions): Rule {
 
     let implementations = '';
     let implementationImports = '';
-    if (options.implements.length > 0) {
-      implementations = options.implements.join(', ');
-      implementationImports = `${implementations}, `;
-      // As long as we aren't in IE... ;)
-      if (options.implements.includes('CanLoad')) {
-        implementationImports = `${implementationImports}Route, UrlSegment, `;
-      }
+    if (options.implements.length === 0) {
+      options.implements.push('CanActivate');
+    }
+    implementations = options.implements.join(', ');
+    implementationImports = `${implementations}, `;
+    // As long as we aren't in IE... ;)
+    if (options.implements.includes('CanLoad')) {
+      implementationImports = `${implementationImports}Route, UrlSegment, `;
     }
 
     const parsedPath = parseName(options.path, options.name);

packages/schematics/angular/guard/index_spec.ts

@@ -105,4 +105,17 @@ describe('Guard Schematic', () => {
       expect(fileString).toContain(functionName);
     });
   });
+
+  it('should use CanActivate if no implements value', async () => {
+    const options = { ...defaultOptions, implements: []};
+    const tree = await schematicRunner.runSchematicAsync('guard', options, appTree)
+      .toPromise();
+    const fileString = tree.readContent('/projects/bar/src/app/foo.guard.ts');
+    expect(fileString).toContain('CanActivate');
+    expect(fileString).toContain('canActivate');
+    expect(fileString).not.toContain('CanActivateChild');
+    expect(fileString).not.toContain('canActivateChild');
+    expect(fileString).not.toContain('CanLoad');
+    expect(fileString).not.toContain('canLoad');
+  });
 });