[Status] Organize metrics stuff into metrics_collector, tests into __test__ directories, remove mock-fs for the cgroup test (#17788)

* [Status] Organize tests into __test__ directories

* custom mock for fs in cgroups test

* work around unhandled rejection errors

* simplify fserror construct

* put fs readFile mockImpl in beforeAll for pretty

* undo hacking the code to suppress unhandled promise rejections

* test files back to sibling of the module

src/server/status/index.js

@@ -1,5 +1,5 @@
 import ServerStatus from './server_status';
-import { Metrics } from './metrics';
+import { Metrics } from './metrics_collector/metrics';
 import { registerStatusPage, registerStatusApi } from './routes';
 
 export function statusMixin(kbnServer, server, config) {

src/server/status/metrics_collector/__mocks__/_fs_stubs.js

@@ -40,3 +40,32 @@ export function cGroups(hierarchy) {
     }
   };
 }
+
+class FSError extends Error {
+  constructor(fileName, code) {
+    super('Stub File Sytem Stub Error: ' + fileName);
+    this.code = code;
+    this.stack = null;
+  }
+}
+
+let _mockFiles = Object.create({});
+
+export const setMockFiles = mockFiles => {
+  _mockFiles = Object.create({});
+  if (mockFiles) {
+    const files = Object.keys(mockFiles);
+    for(const file of files) {
+      _mockFiles[file] = mockFiles[file];
+    }
+  }
+};
+
+export const readFileMock = (fileName, callback) => {
+  if (_mockFiles.hasOwnProperty(fileName)) {
+    callback(null, _mockFiles[fileName]);
+  } else {
+    const err = new FSError(fileName, 'ENOENT');
+    callback(err, null);
+  }
+};

src/server/status/metrics_collector/cgroup.js

@@ -135,9 +135,9 @@ export function getAllStats(options = {}) {
     function rejectUnlessFileNotFound(err) {
       if (err.code === 'ENOENT') {
         resolve(null);
+      } else {
+        reject(err);
       }
-
-      reject(err);
     }
   });
 }

src/server/status/metrics_collector/cgroup.test.js

@@ -1,17 +1,25 @@
-import mockFs from 'mock-fs';
-import { cGroups as cGroupsFsStub } from './_fs_stubs';
+jest.mock('fs', () => ({
+  readFile: jest.fn()
+}));
+
+import fs from 'fs';
+import { cGroups as cGroupsFsStub, setMockFiles, readFileMock } from './__mocks__/_fs_stubs';
 import { getAllStats, readControlGroups, readCPUStat } from './cgroup';
 
 describe('Control Group', function () {
   const fsStub = cGroupsFsStub();
 
+  beforeAll(() => {
+    fs.readFile.mockImplementation(readFileMock);
+  });
+
   afterEach(() => {
-    mockFs.restore();
+    setMockFiles();
   });
 
   describe('readControlGroups', () => {
     it('parses the file', async () => {
-      mockFs({ '/proc/self/cgroup': fsStub.cGroupContents });
+      setMockFiles({ '/proc/self/cgroup': fsStub.cGroupContents });
       const cGroup = await readControlGroups();
 
       expect(cGroup).toEqual({
@@ -34,7 +42,7 @@ describe('Control Group', function () {
 
   describe('readCPUStat', () => {
     it('parses the file', async () => {
-      mockFs({ '/sys/fs/cgroup/cpu/fakeGroup/cpu.stat': fsStub.cpuStatContents });
+      setMockFiles({ '/sys/fs/cgroup/cpu/fakeGroup/cpu.stat': fsStub.cpuStatContents });
       const cpuStat = await readCPUStat('fakeGroup');
 
       expect(cpuStat).toEqual({
@@ -45,7 +53,7 @@ describe('Control Group', function () {
     });
 
     it('returns default stats for missing file', async () => {
-      mockFs();
+      setMockFiles();
       const cpuStat = await readCPUStat('fakeGroup');
 
       expect(cpuStat).toEqual({
@@ -58,7 +66,7 @@ describe('Control Group', function () {
 
   describe('getAllStats', () => {
     it('can override the cpu group path', async () => {
-      mockFs({
+      setMockFiles({
         '/proc/self/cgroup': fsStub.cGroupContents,
         [`${fsStub.cpuAcctDir}/cpuacct.usage`]: '357753491408',
         '/sys/fs/cgroup/cpu/docker/cpu.cfs_period_us': '100000',
@@ -87,7 +95,7 @@ describe('Control Group', function () {
     });
 
     it('handles an undefined control group', async () => {
-      mockFs({
+      setMockFiles({
         '/proc/self/cgroup': '',
         [`${fsStub.cpuAcctDir}/cpuacct.usage`]: '357753491408',
         [`${fsStub.cpuDir}/cpu.stat`]: fsStub.cpuStatContents,
@@ -101,7 +109,7 @@ describe('Control Group', function () {
     });
 
     it('can override the cpuacct group path', async () => {
-      mockFs({
+      setMockFiles({
         '/proc/self/cgroup': fsStub.cGroupContents,
         '/sys/fs/cgroup/cpuacct/docker/cpuacct.usage': '357753491408',
         [`${fsStub.cpuDir}/cpu.cfs_period_us`]: '100000',
@@ -130,7 +138,7 @@ describe('Control Group', function () {
     });
 
     it('extracts control group stats', async () => {
-      mockFs(fsStub.files);
+      setMockFiles(fsStub.files);
       const stats = await getAllStats();
 
       expect(stats).toEqual({
@@ -152,13 +160,13 @@ describe('Control Group', function () {
     });
 
     it('returns null when all files are missing', async () => {
-      mockFs({});
+      setMockFiles();
       const stats = await getAllStats();
       expect(stats).toBeNull();
     });
 
     it('returns null if CPU accounting files are missing', async () => {
-      mockFs({
+      setMockFiles({
         '/proc/self/cgroup': fsStub.cGroupContents,
         [`${fsStub.cpuDir}/cpu.stat`]: fsStub.cpuStatContents
       });
@@ -168,7 +176,7 @@ describe('Control Group', function () {
     });
 
     it('returns -1 stat values if cpuStat file is missing', async () => {
-      mockFs({
+      setMockFiles({
         '/proc/self/cgroup': fsStub.cGroupContents,
         [`${fsStub.cpuAcctDir}/cpuacct.usage`]: '357753491408',
         [`${fsStub.cpuDir}/cpu.cfs_period_us`]: '100000',

src/server/status/metrics_collector/metrics.js

@@ -1,5 +1,5 @@
 import { get, isObject, merge } from 'lodash';
-import { keysToSnakeCaseShallow } from '../../utils/case_conversion';
+import { keysToSnakeCaseShallow } from '../../../utils/case_conversion';
 import { getAllStats as cGroupStats } from './cgroup';
 
 export class Metrics {

src/server/status/metrics_collector/metrics.test.js

@@ -1,8 +1,7 @@
 import _ from 'lodash';
 import sinon from 'sinon';
 import mockFs from 'mock-fs';
-import { cGroups as cGroupsFsStub } from './_fs_stubs';
-
+import { cGroups as cGroupsFsStub } from './__mocks__/_fs_stubs';
 import { Metrics } from './metrics';
 
 describe('Metrics', function () {