From 68f871ae41ea8646be3fa2071fa6ea18eb2600e5 Mon Sep 17 00:00:00 2001
From: Roman Kuznetsov <kuznetsov.roman.orenburg@gmail.com>
Date: Wed, 9 Sep 2026 21:57:05 +0300
Subject: [PATCH] fix: print profiler reports to stderr

---
 src/profiler/output/console.ts      |  2 +-
 test/src/profiler/output/console.ts | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/profiler/output/console.ts b/src/profiler/output/console.ts
index ae150b333..d2d81ed0e 100644
--- a/src/profiler/output/console.ts
+++ b/src/profiler/output/console.ts
@@ -8,7 +8,7 @@ export interface ProfilerConsole {
 }
 
 const defaultConsole: ProfilerConsole = {
-    log: message => console.log(message),
+    log: message => console.error(message),
     warn: message => console.warn(message),
 };
 
diff --git a/test/src/profiler/output/console.ts b/test/src/profiler/output/console.ts
index 0ed44635b..f29e74245 100644
--- a/test/src/profiler/output/console.ts
+++ b/test/src/profiler/output/console.ts
@@ -1,12 +1,16 @@
 import chalk from "chalk";
+import sinon from "sinon";
 
 import { printProfilerResult } from "src/profiler/output/console";
 import type { Finding, ProcessRef, ProfilerConfidence, ProfilerResultV1, RetainedOperation } from "src/profiler/schema";
 
 describe("profiler/output/console", () => {
+    const sandbox = sinon.createSandbox();
     const ansiPattern = new RegExp(`${String.fromCharCode(27)}\\[[0-9;]*m`, "g");
     const withoutColors = (value: string): string => value.replace(ansiPattern, "");
 
+    afterEach(() => sandbox.restore());
+
     const finding = (
         analyzerId: string,
         confidence: ProfilerConfidence,
@@ -135,6 +139,17 @@ describe("profiler/output/console", () => {
         }
     };
 
+    it("should print the default report to stderr", () => {
+        const stdout = sandbox.stub(console, "log");
+        const stderr = sandbox.stub(console, "error");
+
+        printProfilerResult(makeResult());
+
+        assert.notCalled(stdout);
+        assert.calledOnce(stderr);
+        assert.match(stderr.firstCall.args[0], /^\[profiler] Test run profile/);
+    });
+
     it("should print one aligned report with phase and slow-test tables", () => {
         const durationMs = 246_000;
         const session = finding("session-concurrency-v1", "high", 183_000, "chrome", 194);