testutils/timeout.go

// Copyright (c) 2015 Uber Technologies, Inc.

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package testutils

import (
	"fmt"
	"os"
	"runtime"
	"strconv"
	"strings"
	"testing"
	"time"
)

var timeoutScaleFactor = 1.0

func init() {
	if v := os.Getenv("TEST_TIMEOUT_SCALE"); v != "" {
		fv, err := strconv.ParseFloat(v, 64)
		if err != nil {
			panic(err)
		}
		timeoutScaleFactor = fv
		fmt.Fprintln(os.Stderr, "Scaling timeouts by factor", timeoutScaleFactor)
	}
}

// Timeout returns the timeout multiplied by any set multiplier.
func Timeout(timeout time.Duration) time.Duration {
	return time.Duration(timeoutScaleFactor * float64(timeout))
}

// getCallerName returns the test name that called this function.
// It traverses the stack to find the function name directly after a testing.* call.
func getCallerName() string {
	pc := make([]uintptr, 10)
	n := runtime.Callers(2, pc)
	for i := n; i > 0; i-- {
		fname := runtime.FuncForPC(pc[i-1]).Name()
		if strings.HasPrefix(fname, "testing.") {
			return runtime.FuncForPC(pc[i-2]).Name()
		}
	}
	return "unknown"
}

// SetTimeout is used to fail tests after a timeout. It returns a function that should be
// run once the test is complete. The standard way is to use defer, e.g.
// defer SetTimeout(t, time.Second)()
func SetTimeout(t *testing.T, timeout time.Duration) func() {
	timeout = Timeout(timeout)

	caller := getCallerName()

	timer := time.AfterFunc(timeout, func() {
		t.Logf("Test %s timed out after %v", caller, timeout)
		// Unfortunately, tests cannot be failed from new goroutines, so use a panic.
		panic(fmt.Errorf("Test %s timed out after %v", caller, timeout))
	})

	return func() {
		timer.Stop()
	}
}