feat(cli-integ): optionally print memory usage on test start/finish (#419)

To be able to do (basic) memory analysis on different platforms when
needed.

---
By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license

Author: iliapolo

packages/@aws-cdk-testing/cli-integ/lib/integ-test.ts

@@ -43,6 +43,7 @@ export function integTest(
 
     const now = Date.now();
     process.stderr.write(`[INTEG TEST::${name}] Starting (pid ${process.pid})...\n`);
+    maybePrintMemoryUsage(name);
     try {
       if (FAIL_FAST && failed) {
         throw new Error('FAIL_FAST requested and currently failing. Stopping test early.');
@@ -102,6 +103,7 @@ export function integTest(
     } finally {
       const duration = Date.now() - now;
       process.stderr.write(`[INTEG TEST::${name}] Done (${duration} ms).\n`);
+      maybePrintMemoryUsage(name);
     }
   }, timeoutMillis);
 }
@@ -110,6 +112,18 @@ function shouldSkip(testName: string) {
   return SKIP_TESTS.includes(testName);
 }
 
+function maybePrintMemoryUsage(testName: string) {
+  if (process.env.INTEG_MEMORY_DEBUG !== 'true') {
+    return;
+  }
+  const memoryUsage = process.memoryUsage() as any;
+  const report: any = {};
+  for (const [key, value] of Object.entries(memoryUsage)) {
+    report[key] = `${Math.round(value as number / 1024 / 1024)} MB`;
+  }
+  process.stderr.write(`[INTEG TEST::${testName}] Memory Usage: ${JSON.stringify(report)}`);
+}
+
 export function randomString() {
   // Crazy
   return Math.random().toString(36).replace(/[^a-z0-9]+/g, '');