test: don't use exec to test preloaded modules (#696)

PR-URL: #696

test/logger.ts

@@ -0,0 +1,62 @@
+/**
+ * Copyright 2018 Google Inc. All Rights Reserved.
+ *
+ * Licensed 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 {Logger, logger} from '@google-cloud/common';
+
+const PASS_THROUGH_LOG_LEVEL = Number(process.env.GCLOUD_TEST_LOG_LEVEL || 0);
+
+// tslint:disable-next-line:no-any
+type LoggerFunction = (message: any, ...args: any[]) => void;
+
+export class TestLogger implements Logger {
+  private logs:
+      {[k in keyof Logger]:
+           string[]} = {error: [], warn: [], info: [], debug: [], silly: []};
+  private innerLogger = logger({level: logger.LEVELS[PASS_THROUGH_LOG_LEVEL]});
+
+  private makeLoggerFn(logLevel: keyof Logger): LoggerFunction {
+    // TODO(kjin): When we drop support for Node 4, use spread args.
+    const that = this;
+    return function(this: null) {
+      const args = Array.prototype.slice.call(arguments, 0);
+      that.logs[logLevel].push(args.join(' '));
+      that.innerLogger[logLevel].apply(this, args);
+    };
+  }
+
+  error = this.makeLoggerFn('error');
+  warn = this.makeLoggerFn('warn');
+  info = this.makeLoggerFn('info');
+  debug = this.makeLoggerFn('debug');
+  silly = this.makeLoggerFn('silly');
+
+  getLogs(logLevel: keyof Logger): string[] {
+    return this.logs[logLevel];
+  }
+
+  getNumLogsWith(logLevel: keyof Logger, strOrReg: string|RegExp): number {
+    if (typeof strOrReg === 'string') {
+      return this.logs[logLevel].filter(line => line.includes(strOrReg)).length;
+    } else {
+      return this.logs[logLevel].filter(line => line.match(strOrReg)).length;
+    }
+  }
+
+  clearLogs(): void {
+    (Object.keys(this.logs) as Array<keyof Logger>)
+        .forEach(logLevel => this.logs[logLevel].length = 0);
+  }
+}

test/test-modules-loaded-before-agent.ts

@@ -14,18 +14,32 @@
  * limitations under the License.
  */
 
-'use strict';
+import * as common from '@google-cloud/common';
+import * as assert from 'assert';
+import * as shimmer from 'shimmer';
 
-var assert = require('assert');
-var cp = require('child_process');
+import {TestLogger} from './logger';
+import * as trace from './trace';
 
-describe('modules loaded before agent', function() {
-  it('should log if modules were loaded before agent', function() {
-    var output =
-      cp.execSync('node test/fixtures/start-agent.js');
-    console.log(output.toString());
-    assert(output.toString().match(/Tracing might not work.*"glob".*/));
+describe('modules loaded before agent', () => {
+  const logger = new TestLogger();
+
+  before(() => {
+    const LEVELS = common.logger.LEVELS;
+    shimmer.wrap(common, 'logger', () => {
+      return Object.assign(() => logger, {LEVELS});
+    });
+  });
+
+  after(() => {
+    shimmer.unwrap(common, 'logger');
   });
-});
 
-export default {};
+  it('should log if modules were loaded before agent', () => {
+    trace.start();
+    assert.strictEqual(
+        logger.getNumLogsWith(
+            'error', /modules.*loaded.*before.*trace agent.*: .*"shimmer"/),
+        1);
+  });
+});

tsconfig.json

@@ -17,8 +17,10 @@
     "src/plugins/plugin-koa.ts",
     "src/plugins/plugin-restify.ts",
     "test/plugins/test-trace-http2.ts",
+    "test/logger.ts",
     "test/nocks.ts",
     "test/test-config-credentials.ts",
+    "test/test-modules-loaded-before-agent.ts",
     "test/test-trace-cluster.ts",
     "test/test-trace-web-frameworks.ts",
     "test/trace.ts",