fix(@angular-devkit/core): show allowed enum values when validation on enum fails

(cherry picked from commit 600d266)

Author: alan-agius4

packages/angular_devkit/core/src/json/schema/registry.ts

@@ -63,8 +63,16 @@ export class SchemaValidationException extends BaseException {
 
     const messages = errors.map((err) => {
       let message = `Data path ${JSON.stringify(err.instancePath)} ${err.message}`;
-      if (err.keyword === 'additionalProperties') {
-        message += `(${err.params.additionalProperty})`;
+      switch (err.keyword) {
+        case 'additionalProperties':
+          message += `(${err.params.additionalProperty})`;
+          break;
+
+        case 'enum':
+          message += `. Allowed values are: ${(err.params.allowedValues as string[] | undefined)
+            ?.map((v) => `"${v}"`)
+            .join(', ')}`;
+          break;
       }
 
       return message + '.';

packages/angular_devkit/core/src/json/schema/registry_spec.ts

@@ -9,7 +9,7 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { map, mergeMap } from 'rxjs/operators';
 import { SchemaFormat } from './interface';
-import { CoreSchemaRegistry } from './registry';
+import { CoreSchemaRegistry, SchemaValidationException } from './registry';
 import { addUndefinedDefaults } from './transforms';
 
 describe('CoreSchemaRegistry', () => {
@@ -138,6 +138,31 @@ describe('CoreSchemaRegistry', () => {
       .then(done, done.fail);
   });
 
+  it('fails on invalid enum value', (done) => {
+    const registry = new CoreSchemaRegistry();
+    registry.addPostTransform(addUndefinedDefaults);
+    const data = { packageManager: 'foo' };
+
+    registry
+      .compile({
+        properties: {
+          packageManager: { type: 'string', enum: ['npm', 'yarn', 'pnpm', 'cnpm'] },
+        },
+        additionalProperties: false,
+      })
+      .pipe(
+        mergeMap((validator) => validator(data)),
+        map((result) => {
+          expect(result.success).toBe(false);
+          expect(new SchemaValidationException(result.errors).message).toContain(
+            `Data path "/packageManager" must be equal to one of the allowed values. Allowed values are: "npm", "yarn", "pnpm", "cnpm".`,
+          );
+        }),
+      )
+      .toPromise()
+      .then(done, done.fail);
+  });
+
   it('fails on invalid additionalProperties async', (done) => {
     const registry = new CoreSchemaRegistry();
     registry.addPostTransform(addUndefinedDefaults);