Fix flaky jest test (elastic#58402)

* Revert "Temporarily removes kbn-optimizer cache key tests (elastic#58318)"

This reverts commit e64eff0.

* [kbn-optmizer] avoid mocking fs exports

* overwrite ciGroup script to support jest in flaky testing job

* limit jest workers to 3 so that concurrent runners have space to operate

* Revert "limit jest workers to 3 so that concurrent runners have space to operate"

This reverts commit 1a2f882.

* Revert "overwrite ciGroup script to support jest in flaky testing job"

This reverts commit 548db61.

packages/kbn-optimizer/src/optimizer/cache_keys.test.ts

@@ -0,0 +1,208 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import Path from 'path';
+
+import jestDiff from 'jest-diff';
+import { REPO_ROOT, createAbsolutePathSerializer } from '@kbn/dev-utils';
+
+import { reformatJestDiff, getOptimizerCacheKey, diffCacheKey } from './cache_keys';
+import { OptimizerConfig } from './optimizer_config';
+
+jest.mock('./get_changes.ts', () => ({
+  getChanges: async () =>
+    new Map([
+      ['/foo/bar/a', 'modified'],
+      ['/foo/bar/b', 'modified'],
+      ['/foo/bar/c', 'deleted'],
+    ]),
+}));
+
+jest.mock('./get_mtimes.ts', () => ({
+  getMtimes: async (paths: string[]) => new Map(paths.map(path => [path, 12345])),
+}));
+
+jest.mock('execa');
+
+jest.mock('fs', () => {
+  const realFs = jest.requireActual('fs');
+  return {
+    ...realFs,
+    readFile: jest.fn(realFs.readFile),
+  };
+});
+
+expect.addSnapshotSerializer(createAbsolutePathSerializer());
+
+jest.requireMock('execa').mockImplementation(async (cmd: string, args: string[], opts: object) => {
+  expect(cmd).toBe('git');
+  expect(args).toEqual([
+    'log',
+    '-n',
+    '1',
+    '--pretty=format:%H',
+    '--',
+    expect.stringContaining('kbn-optimizer'),
+  ]);
+  expect(opts).toEqual({
+    cwd: REPO_ROOT,
+  });
+
+  return {
+    stdout: '<last commit sha>',
+  };
+});
+
+describe('getOptimizerCacheKey()', () => {
+  it('uses latest commit, bootstrap cache, and changed files to create unique value', async () => {
+    jest
+      .requireMock('fs')
+      .readFile.mockImplementation(
+        (path: string, enc: string, cb: (err: null, file: string) => void) => {
+          expect(path).toBe(
+            Path.resolve(REPO_ROOT, 'packages/kbn-optimizer/target/.bootstrap-cache')
+          );
+          expect(enc).toBe('utf8');
+          cb(null, '<bootstrap cache>');
+        }
+      );
+
+    const config = OptimizerConfig.create({
+      repoRoot: REPO_ROOT,
+    });
+
+    await expect(getOptimizerCacheKey(config)).resolves.toMatchInlineSnapshot(`
+            Object {
+              "bootstrap": "<bootstrap cache>",
+              "deletedPaths": Array [
+                "/foo/bar/c",
+              ],
+              "lastCommit": "<last commit sha>",
+              "modifiedTimes": Object {
+                "/foo/bar/a": 12345,
+                "/foo/bar/b": 12345,
+              },
+              "workerConfig": Object {
+                "browserslistEnv": "dev",
+                "cache": true,
+                "dist": false,
+                "optimizerCacheKey": "♻",
+                "profileWebpack": false,
+                "repoRoot": <absolute path>,
+                "watch": false,
+              },
+            }
+          `);
+  });
+});
+
+describe('diffCacheKey()', () => {
+  it('returns undefined if values are equal', () => {
+    expect(diffCacheKey('1', '1')).toBe(undefined);
+    expect(diffCacheKey(1, 1)).toBe(undefined);
+    expect(diffCacheKey(['1', '2', { a: 'b' }], ['1', '2', { a: 'b' }])).toBe(undefined);
+    expect(
+      diffCacheKey(
+        {
+          a: '1',
+          b: '2',
+        },
+        {
+          b: '2',
+          a: '1',
+        }
+      )
+    ).toBe(undefined);
+  });
+
+  it('returns a diff if the values are different', () => {
+    expect(diffCacheKey(['1', '2', { a: 'b' }], ['1', '2', { b: 'a' }])).toMatchInlineSnapshot(`
+      "- Expected
+      + Received
+
+        Array [
+          \\"1\\",
+          \\"2\\",
+          Object {
+      -     \\"a\\": \\"b\\",
+      +     \\"b\\": \\"a\\",
+          },
+        ]"
+    `);
+    expect(
+      diffCacheKey(
+        {
+          a: '1',
+          b: '1',
+        },
+        {
+          b: '2',
+          a: '2',
+        }
+      )
+    ).toMatchInlineSnapshot(`
+      "- Expected
+      + Received
+
+        Object {
+      -   \\"a\\": \\"1\\",
+      -   \\"b\\": \\"1\\",
+      +   \\"a\\": \\"2\\",
+      +   \\"b\\": \\"2\\",
+        }"
+    `);
+  });
+});
+
+describe('reformatJestDiff()', () => {
+  it('reformats large jestDiff output to focus on the changed lines', () => {
+    const diff = jestDiff(
+      {
+        a: ['1', '1', '1', '1', '1', '1', '1', '2', '1', '1', '1', '1', '1', '1', '1', '1', '1'],
+      },
+      {
+        b: ['1', '1', '1', '1', '1', '1', '1', '1', '1', '1', '1', '1', '2', '1', '1', '1', '1'],
+      }
+    );
+
+    expect(reformatJestDiff(diff)).toMatchInlineSnapshot(`
+      "- Expected
+      + Received
+
+        Object {
+      -   \\"a\\": Array [
+      +   \\"b\\": Array [
+            \\"1\\",
+            \\"1\\",
+            ...
+            \\"1\\",
+            \\"1\\",
+      -     \\"2\\",
+            \\"1\\",
+            \\"1\\",
+            ...
+            \\"1\\",
+            \\"1\\",
+      +     \\"2\\",
+            \\"1\\",
+            \\"1\\",
+            ..."
+    `);
+  });
+});