Implement tests for chrome launcher.

* Refactor code bits to make testable. * Add the ability for a user to pass in module mocks to enable testing.
GoogleChrome · Jun 5, 2017 · 0fe2fa8 · 0fe2fa8
1 parent 32fcb44
commit 0fe2fa8
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Showing 2 changed files with 99 additions and 38 deletions.
diff --git a/chrome-launcher/chrome-launcher.ts b/chrome-launcher/chrome-launcher.ts
@@ -50,6 +50,8 @@ export interface LaunchedChrome {
   kill: () => Promise<{}>;
 }
 
+export interface ModuleOverrides { fs?: typeof fs, rimraf?: typeof rimraf, }
+
 export async function launch(opts: Options = {}): Promise<LaunchedChrome> {
   opts.handleSIGINT = defaults(opts.handleSIGINT, true);
 
@@ -73,17 +75,23 @@ export class Launcher {
   private pollInterval: number = 500;
   private pidFile: string;
   private startingUrl: string;
-  private userDataDir?: string;
   private outFile?: number;
   private errFile?: number;
   private chromePath?: string;
   private chromeFlags: string[];
   private requestedPort?: number;
-  chrome?: childProcess.ChildProcess;
+  private chrome?: childProcess.ChildProcess;
+  private fs: typeof fs;
+  private rimraf: typeof rimraf;
+
+  userDataDir?: string;
   port?: number;
   pid?: number;
 
-  constructor(private opts: Options = {}) {
+  constructor(private opts: Options = {}, moduleOverrides: ModuleOverrides = {}) {
+    this.fs = moduleOverrides.fs || fs;
+    this.rimraf = moduleOverrides.rimraf || rimraf;
+
     // choose the first one (default)
     this.startingUrl = defaults(this.opts.startingUrl, 'about:blank');
     this.chromeFlags = defaults(this.opts.chromeFlags, []);
@@ -108,16 +116,20 @@ export class Launcher {
     return flags;
   }
 
-  private prepare() {
+  // Wrapper function to enable easy testing.
+  makeTmpDir() {
+    return makeTmpDir();
+  }
+
+  prepare() {
     const platform = process.platform as SupportedPlatforms;
     if (!_SUPPORTED_PLATFORMS.has(platform)) {
       throw new Error(`Platform ${platform} is not supported`);
     }
 
-    this.userDataDir = this.opts.userDataDir || makeTmpDir();
-
-    this.outFile = fs.openSync(`${this.userDataDir}/chrome-out.log`, 'a');
-    this.errFile = fs.openSync(`${this.userDataDir}/chrome-err.log`, 'a');
+    this.userDataDir = this.opts.userDataDir || this.makeTmpDir();
+    this.outFile = this.fs.openSync(`${this.userDataDir}/chrome-out.log`, 'a');
+    this.errFile = this.fs.openSync(`${this.userDataDir}/chrome-err.log`, 'a');
 
     // fix for Node4
     // you can't pass a fd to fs.writeFileSync
@@ -180,7 +192,7 @@ export class Launcher {
           execPath, this.flags, {detached: true, stdio: ['ignore', this.outFile, this.errFile]});
       this.chrome = chrome;
 
-      fs.writeFileSync(this.pidFile, chrome.pid.toString());
+      this.fs.writeFileSync(this.pidFile, chrome.pid.toString());
 
       log.verbose('ChromeLauncher', `Chrome running with pid ${chrome.pid} on port ${this.port}.`);
       resolve(chrome.pid);
@@ -249,10 +261,7 @@ export class Launcher {
     return new Promise(resolve => {
       if (this.chrome) {
         this.chrome.on('close', () => {
-          // Only clean up the tmp dir if we created it.
-          if (this.opts.userDataDir === undefined) {
-            this.destroyTmp().then(resolve);
-          }
+          this.destroyTmp().then(resolve);
         });
 
         log.log('ChromeLauncher', 'Killing all Chrome Instances');
@@ -274,25 +283,24 @@ export class Launcher {
     });
   }
 
-  private destroyTmp() {
+  destroyTmp() {
     return new Promise(resolve => {
-      if (!this.userDataDir) {
+      // Only clean up the tmp dir if we created it.
+      if (this.userDataDir === undefined || this.opts.userDataDir !== undefined) {
         return resolve();
       }
 
-      log.verbose('ChromeLauncher', `Removing ${this.userDataDir}`);
-
       if (this.outFile) {
-        fs.closeSync(this.outFile);
+        this.fs.closeSync(this.outFile);
         delete this.outFile;
       }
 
       if (this.errFile) {
-        fs.closeSync(this.errFile);
+        this.fs.closeSync(this.errFile);
         delete this.errFile;
       }
 
-      rimraf(this.userDataDir, () => resolve());
+      this.rimraf(this.userDataDir, () => resolve());
     });
   }
 };
diff --git a/chrome-launcher/test/chrome-launcher-test.ts b/chrome-launcher/test/chrome-launcher-test.ts
@@ -18,32 +18,85 @@
 
 import {Launcher} from '../chrome-launcher';
 
+import * as assert from 'assert';
+
 const log = require('../../lighthouse-core/lib/log');
-const assert = require('assert');
+const fsMock = {
+  openSync: () => {},
+  closeSync: () => {}
+};
 
 describe('Launcher', () => {
-  it('doesn\'t fail when killed twice', () => {
+  it('accepts and uses a custom path', async () => {
+    log.setLevel('error');
+    let callCount = 0;
+    const rimrafMock = (_: string, done: () => void) => {
+      callCount++;
+      done();
+    };
+
+    const chromeInstance =
+        new Launcher({userDataDir: 'some_path'}, {fs: fsMock as any, rimraf: rimrafMock as any});
+
+    chromeInstance.prepare();
+
+    await chromeInstance.destroyTmp();
+    assert.strictEqual(callCount, 0);
+  });
+
+  it('cleans up the tmp dir after closing', async () => {
+    log.setLevel('error');
+    let callCount = 0;
+    const rimrafMock = (_: string, done: () => void) => {
+      callCount++;
+      done();
+    };
+
+    const chromeInstance = new Launcher({}, {fs: fsMock as any, rimraf: rimrafMock as any});
+
+    chromeInstance.prepare();
+    await chromeInstance.destroyTmp();
+    assert.strictEqual(callCount, 1);
+  });
+
+  it('does not delete created directory when custom path passed', () => {
+    log.setLevel('error');
+
+    const chromeInstance = new Launcher({userDataDir: 'some_path'}, {fs: fsMock as any});
+
+    chromeInstance.prepare();
+    assert.equal(chromeInstance.userDataDir, 'some_path');
+  });
+
+  it('defaults to genering a tmp dir when no data dir is passed', () => {
+    log.setLevel('error');
+    const chromeInstance = new Launcher({}, {fs: fsMock as any});
+    const originalMakeTmp = chromeInstance.makeTmpDir;
+    chromeInstance.makeTmpDir = () => 'tmp_dir'
+    chromeInstance.prepare()
+    assert.equal(chromeInstance.userDataDir, 'tmp_dir');
+
+    // Restore the original fn.
+    chromeInstance.makeTmpDir = originalMakeTmp;
+  });
+
+  it('doesn\'t fail when killed twice', async () => {
     log.setLevel('error');
     const chromeInstance = new Launcher();
-    return chromeInstance.launch().then(() => {
-      log.setLevel();
-      return Promise.all([chromeInstance.kill(), chromeInstance.kill()]);
-    });
+    await chromeInstance.launch();
+    log.setLevel();
+    await chromeInstance.kill();
+    await chromeInstance.kill();
   });
 
-  it('doesn\'t launch multiple chrome processes', () => {
+  it('doesn\'t launch multiple chrome processes', async () => {
     log.setLevel('error');
     const chromeInstance = new Launcher();
-    let pid: number;
-    return chromeInstance.launch()
-        .then(() => {
-          pid = chromeInstance.chrome!.pid;
-          return chromeInstance.launch();
-        })
-        .then(() => {
-          log.setLevel();
-          assert.strictEqual(pid, chromeInstance.chrome!.pid);
-          return chromeInstance.kill();
-        });
+    await chromeInstance.launch();
+    let pid = chromeInstance.pid!;
+    await chromeInstance.launch();
+    log.setLevel();
+    assert.strictEqual(pid, chromeInstance.pid);
+    await chromeInstance.kill();
   });
 });