[Cases] Total users returned by suggested users API (#161329)

Connected to #146945

## Summary

| Description  | Limit | Done? | Documented?
| ------------- | ---- | :---: | ---- |
| Total number of users returned by suggest users API | 10 |
✅ | No (internal) |

### Checklist

Delete any items that are not applicable to this PR.

- [x]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

x-pack/plugins/cases/common/api/cases/user_profile.test.ts

@@ -5,6 +5,8 @@
  * 2.0.
  */
 
+import { PathReporter } from 'io-ts/lib/PathReporter';
+import { MAX_SUGGESTED_PROFILES } from '../../constants';
 import { SuggestUserProfilesRequestRt, CaseUserProfileRt } from './user_profiles';
 
 describe('userProfile', () => {
@@ -44,6 +46,21 @@ describe('userProfile', () => {
       });
     });
 
+    it('missing size parameter works correctly', () => {
+      const query = SuggestUserProfilesRequestRt.decode({
+        name: 'di maria',
+        owners: ['benfica'],
+      });
+
+      expect(query).toStrictEqual({
+        _tag: 'Right',
+        right: {
+          name: 'di maria',
+          owners: ['benfica'],
+        },
+      });
+    });
+
     it('removes foo:bar attributes from request', () => {
       const query = SuggestUserProfilesRequestRt.decode({ ...defaultRequest, foo: 'bar' });
 
@@ -56,6 +73,24 @@ describe('userProfile', () => {
         },
       });
     });
+
+    it(`does not accept size param bigger than ${MAX_SUGGESTED_PROFILES}`, () => {
+      const query = SuggestUserProfilesRequestRt.decode({
+        ...defaultRequest,
+        size: MAX_SUGGESTED_PROFILES + 1,
+      });
+
+      expect(PathReporter.report(query)).toContain('The size field cannot be more than 10.');
+    });
+
+    it('does not accept size param lower than 1', () => {
+      const query = SuggestUserProfilesRequestRt.decode({
+        ...defaultRequest,
+        size: 0,
+      });
+
+      expect(PathReporter.report(query)).toContain('The size field cannot be less than 1.');
+    });
   });
 
   describe('CaseUserProfileRt', () => {

x-pack/plugins/cases/common/api/cases/user_profiles.ts

@@ -6,13 +6,19 @@
  */
 
 import * as rt from 'io-ts';
+import { MAX_SUGGESTED_PROFILES } from '../../constants';
+import { limitedNumberSchema } from '../../schema';
 
 export const SuggestUserProfilesRequestRt = rt.intersection([
   rt.strict({
     name: rt.string,
     owners: rt.array(rt.string),
   }),
-  rt.exact(rt.partial({ size: rt.number })),
+  rt.exact(
+    rt.partial({
+      size: limitedNumberSchema({ fieldName: 'size', min: 1, max: MAX_SUGGESTED_PROFILES }),
+    })
+  ),
 ]);
 
 export type SuggestUserProfilesRequest = rt.TypeOf<typeof SuggestUserProfilesRequestRt>;

x-pack/plugins/cases/common/constants/index.ts

@@ -124,6 +124,7 @@ export const MAX_COMMENT_LENGTH = 30000 as const;
 export const MAX_LENGTH_PER_TAG = 256 as const;
 export const MAX_TAGS_PER_CASE = 200 as const;
 export const MAX_DELETE_IDS_LENGTH = 100 as const;
+export const MAX_SUGGESTED_PROFILES = 10 as const;
 export const MAX_CASES_TO_UPDATE = 100 as const;
 
 /**

x-pack/plugins/cases/common/schema/index.test.ts

@@ -7,7 +7,13 @@
 
 import { PathReporter } from 'io-ts/lib/PathReporter';
 
-import { limitedArraySchema, limitedStringSchema, NonEmptyString, paginationSchema } from '.';
+import {
+  limitedArraySchema,
+  limitedNumberSchema,
+  limitedStringSchema,
+  NonEmptyString,
+  paginationSchema,
+} from '.';
 import { MAX_DOCS_PER_PAGE } from '../constants';
 
 describe('schema', () => {
@@ -281,4 +287,36 @@ describe('schema', () => {
           `);
     });
   });
+
+  describe('limitedNumberSchema', () => {
+    it('works correctly the number is between min and max', () => {
+      expect(
+        PathReporter.report(limitedNumberSchema({ fieldName: 'foo', min: 0, max: 2 }).decode(1))
+      ).toMatchInlineSnapshot(`
+        Array [
+          "No errors!",
+        ]
+      `);
+    });
+
+    it('fails when given a number that is lower than the minimum', () => {
+      expect(
+        PathReporter.report(limitedNumberSchema({ fieldName: 'foo', min: 1, max: 2 }).decode(0))
+      ).toMatchInlineSnapshot(`
+        Array [
+          "The foo field cannot be less than 1.",
+        ]
+      `);
+    });
+
+    it('fails when given number that is higher than the maximum', () => {
+      expect(
+        PathReporter.report(limitedNumberSchema({ fieldName: 'foo', min: 1, max: 2 }).decode(3))
+      ).toMatchInlineSnapshot(`
+        Array [
+          "The foo field cannot be more than 2.",
+        ]
+      `);
+    });
+  });
 });

x-pack/plugins/cases/common/schema/index.ts

@@ -134,3 +134,22 @@ export const paginationSchema = ({ maxPerPage }: { maxPerPage: number }) =>
     rt.identity,
     undefined
   );
+
+export const limitedNumberSchema = ({ fieldName, min, max }: LimitedSchemaType) =>
+  new rt.Type<number, number, unknown>(
+    'LimitedNumber',
+    rt.number.is,
+    (input, context) =>
+      either.chain(rt.number.validate(input, context), (s) => {
+        if (s < min) {
+          return rt.failure(input, context, `The ${fieldName} field cannot be less than ${min}.`);
+        }
+
+        if (s > max) {
+          return rt.failure(input, context, `The ${fieldName} field cannot be more than ${max}.`);
+        }
+
+        return rt.success(s);
+      }),
+    rt.identity
+  );

x-pack/plugins/cases/server/services/user_profiles/index.test.ts

@@ -0,0 +1,33 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { MAX_SUGGESTED_PROFILES } from '../../../common/constants';
+import { loggingSystemMock } from '@kbn/core/server/mocks';
+import { UserProfileService } from '.';
+
+describe('suggest', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('throws with invalid size field', async () => {
+    const mockLogger = loggingSystemMock.createLogger();
+    const userProfileService = new UserProfileService(mockLogger);
+    await expect(
+      // @ts-ignore: irrelevant missing parameters
+      userProfileService.suggest({
+        body: {
+          name: 'antonio',
+          owners: [],
+          size: MAX_SUGGESTED_PROFILES + 1,
+        },
+      })
+    ).rejects.toThrow(
+      `Failed to retrieve suggested user profiles in service: Error: The size field cannot be more than ${MAX_SUGGESTED_PROFILES}.`
+    );
+  });
+});

x-pack/test/api_integration/apis/cases/suggest_user_profiles.ts

@@ -6,7 +6,7 @@
  */
 
 import expect from '@kbn/expect';
-import { APP_ID as CASES_APP_ID } from '@kbn/cases-plugin/common/constants';
+import { APP_ID as CASES_APP_ID, MAX_SUGGESTED_PROFILES } from '@kbn/cases-plugin/common/constants';
 import { APP_ID as SECURITY_SOLUTION_APP_ID } from '@kbn/security-solution-plugin/common/constants';
 import { observabilityFeatureId as OBSERVABILITY_APP_ID } from '@kbn/observability-plugin/common';
 import { FtrProviderContext } from '../../ftr_provider_context';
@@ -76,5 +76,20 @@ export default ({ getService }: FtrProviderContext): void => {
         });
       });
     }
+
+    describe('errors', () => {
+      it('400s when size parameter is not valid', async () => {
+        await suggestUserProfiles({
+          supertest: supertestWithoutAuth,
+          req: {
+            name: casesAllUser.username,
+            owners: [CASES_APP_ID],
+            size: MAX_SUGGESTED_PROFILES + 1,
+          },
+          auth: { user: casesAllUser, space: null },
+          expectedHttpCode: 400,
+        });
+      });
+    });
   });
 };