chore(infrastructure): Fail builds on non-zero exit codes (#3211)

```bash
npm run screenshot:test
```

![image](https://user-images.githubusercontent.com/409245/43218543-87ae6c1c-8ff9-11e8-800c-e80457c0d08d.png)

![image](https://user-images.githubusercontent.com/409245/43218559-943f8aec-8ff9-11e8-9166-774102ca3794.png)

test/screenshot/infra/commands/build.js

@@ -55,8 +55,8 @@ class BuildCommand {
 
     this.logger_.foldStart('screenshot.build', 'Compiling source files');
 
-    this.buildProtoFiles_(shouldWatch);
-    this.buildHtmlFiles_(shouldWatch);
+    await this.buildProtoFiles_(shouldWatch);
+    await this.buildHtmlFiles_(shouldWatch);
 
     if (shouldWatch) {
       this.processManager_.spawnChildProcess('npm', ['run', 'screenshot:webpack', '--', '--watch']);
@@ -71,12 +71,12 @@ class BuildCommand {
    * @param {boolean} shouldWatch
    * @private
    */
-  buildProtoFiles_(shouldWatch) {
-    const buildRightNow = () => this.protoCommand_.runAsync();
+  async buildProtoFiles_(shouldWatch) {
+    const buildRightNow = async () => this.protoCommand_.runAsync(shouldWatch);
     const buildDelayed = debounce(buildRightNow, 1000);
 
     if (!shouldWatch) {
-      buildRightNow();
+      await buildRightNow();
       return;
     }
 
@@ -93,12 +93,12 @@ class BuildCommand {
    * @param {boolean} shouldWatch
    * @private
    */
-  buildHtmlFiles_(shouldWatch) {
-    const buildRightNow = () => this.indexCommand_.runAsync();
+  async buildHtmlFiles_(shouldWatch) {
+    const buildRightNow = async () => this.indexCommand_.runAsync();
     const buildDelayed = debounce(buildRightNow, 1000);
 
     if (!shouldWatch) {
-      buildRightNow();
+      await buildRightNow();
       return;
     }
 

test/screenshot/infra/commands/proto.js

@@ -24,9 +24,10 @@ const {TEST_DIR_RELATIVE_PATH} = require('../lib/constants');
 
 class ProtoCommand {
   /**
+   * @param {boolean} isWatching
    * @return {!Promise<number|undefined>} Process exit code. If no exit code is returned, `0` is assumed.
    */
-  async runAsync() {
+  async runAsync(isWatching = false) {
     const processManager = new ProcessManager();
     const protoFilePaths = glob.sync(path.join(TEST_DIR_RELATIVE_PATH, '**/*.proto'));
 
@@ -35,7 +36,9 @@ class ProtoCommand {
 
     for (const protoFilePath of protoFilePaths) {
       const jsFilePath = protoFilePath.replace(/.proto$/, '.pb.js');
-      processManager.spawnChildProcessSync(cmd, args.concat(`--out=${jsFilePath}`, protoFilePath));
+      processManager.spawnChildProcessSync(
+        cmd, args.concat(`--out=${jsFilePath}`, protoFilePath), undefined, isWatching
+      );
     }
   }
 }

test/screenshot/infra/lib/cloud-storage.js

@@ -85,28 +85,18 @@ class CloudStorage {
       return;
     }
 
-    console.log(`\nUploading ${noun} to GCS...\n`);
-
-    /** @type {!ChildProcessSpawnResult} */
-    const gsutilProcess = await this.spawnGsutilUploadProcess_(reportData, localSourceDir);
-
-    /** @type {number} */
-    const exitCode = gsutilProcess.status;
-
+    console.log(`Uploading ${noun} to GCS...\n`);
+    this.spawnGsutilUploadProcess_(reportData, localSourceDir);
     console.log('');
-
-    if (exitCode !== 0) {
-      throw new Error(`gsutil processes exited with code ${exitCode}`);
-    }
   }
 
   /**
    * @param {!mdc.proto.ReportData} reportData
    * @param {string} localSourceDir
-   * @return {!Promise<!ChildProcessSpawnResult>}
+   * @return {!SpawnSyncReturns}
    * @private
    */
-  async spawnGsutilUploadProcess_(reportData, localSourceDir) {
+  spawnGsutilUploadProcess_(reportData, localSourceDir) {
     const removeTrailingSlash = (filePath) => filePath.replace(new RegExp('/+$'), '');
 
     // Normalize directory paths by removing trailing slashes

test/screenshot/infra/lib/process-manager.js

@@ -18,6 +18,7 @@
 
 const childProcess = require('child_process');
 const ps = require('ps-node');
+const {ExitCode} = require('../lib/constants');
 
 class ProcessManager {
   /**
@@ -46,9 +47,10 @@ class ProcessManager {
    * @param {string} cmd
    * @param {!Array<string>} args
    * @param {!ChildProcessSpawnOptions=} opts
-   * @return {!ChildProcessSpawnResult}
+   * @param {boolean=} isWatching
+   * @return {!SpawnSyncReturns}
    */
-  spawnChildProcessSync(cmd, args, opts = {}) {
+  spawnChildProcessSync(cmd, args, opts = {}, isWatching = false) {
     /** @type {!ChildProcessSpawnOptions} */
     const defaultOpts = {
       stdio: 'inherit',
@@ -61,7 +63,16 @@ class ProcessManager {
 
     console.log(`${cmd} ${args.join(' ')}`);
 
-    return childProcess.spawnSync(cmd, args, mergedOpts);
+    const result = childProcess.spawnSync(cmd, args, mergedOpts);
+    if (result.status !== ExitCode.OK) {
+      const message = `${cmd} process exited with code ${result.status}`;
+      if (isWatching) {
+        console.error(message);
+      } else {
+        throw new Error(message);
+      }
+    }
+    return result;
   }
 
   /**

test/screenshot/infra/types/node-api-externs.js

@@ -34,14 +34,6 @@
  * }} ChildProcessSpawnOptions
  */
 
-/**
- * @typedef {{
- *   status: number,
- *   signal: ?string,
- *   pid: number,
- * }} ChildProcessSpawnResult
- */
-
 
 /*
  * Resemble.js API

test/screenshot/run.js

@@ -87,15 +87,15 @@ process.on('exit', () => {
 });
 
 // TODO(acdvorak): Create a centralized class to manage global exit handlers
-process.on('unhandledRejection', (error) => {
+process.on('unhandledRejection', (err) => {
   const message = [
     'UnhandledPromiseRejectionWarning: Unhandled promise rejection.',
     'This error originated either by throwing inside of an async function without a catch block,',
     'or by rejecting a promise which was not handled with .catch().',
   ].join(' ');
   console.error('\n');
   console.error(message);
-  console.error(error);
+  console.error(formatError(err));
   process.exit(ExitCode.UNHANDLED_PROMISE_REJECTION);
 });