How to Suppress or Filter Logs in Tests

Testing
2026-04-17T12:05:42+00:00
Suppress Go test logs by redirecting os.Stdout to io.Discard or using t.Log for conditional output.

Use t.Log() or t.Logf() to capture output in test logs, or redirect os.Stdout to io.Discard to suppress it entirely.

import (
	"io"
	"os"
	"testing"
)

func TestExample(t *testing.T) {
	// Suppress all stdout/stderr during this test
	oldStdout := os.Stdout
	os.Stdout = io.Discard
	defer func() { os.Stdout = oldStdout }()

	// Your test code here
	// Output will be hidden from the test runner
}

For filtering specific log lines, wrap os.Stdout with a custom io.Writer that implements Write() to check and drop unwanted strings before writing to the original stream.