open-nomad/helper/testlog/testlog.go
2018-03-21 16:49:48 -07:00

59 lines
1.5 KiB
Go

// Package testlog creates a *log.Logger backed by *testing.T to ease logging
// in tests. This allows logs from components being tested to only be printed
// if the test fails (or the verbose flag is specified).
package testlog
import (
"io"
"log"
"os"
)
// UseStdout returns true if NOMAD_TEST_STDOUT=1 and sends logs to stdout.
func UseStdout() bool {
return os.Getenv("NOMAD_TEST_STDOUT") == "1"
}
// LogPrinter is the methods of testing.T (or testing.B) needed by the test
// logger.
type LogPrinter interface {
Logf(format string, args ...interface{})
}
// writer implements io.Writer on top of a Logger.
type writer struct {
t LogPrinter
}
// Write to an underlying Logger. Never returns an error.
func (w *writer) Write(p []byte) (n int, err error) {
w.t.Logf(string(p))
return len(p), nil
}
// NewWriter creates a new io.Writer backed by a Logger.
func NewWriter(t LogPrinter) io.Writer {
if UseStdout() {
return os.Stdout
}
return &writer{t}
}
// New returns a new test logger. See https://golang.org/pkg/log/#New
func New(t LogPrinter, prefix string, flag int) *log.Logger {
if UseStdout() {
return log.New(os.Stdout, prefix, flag)
}
return log.New(&writer{t}, prefix, flag)
}
// WithPrefix returns a new test logger with the Lmicroseconds flag set.
func WithPrefix(t LogPrinter, prefix string) *log.Logger {
return New(t, prefix, log.Lmicroseconds)
}
// NewLog logger with "TEST" prefix and the Lmicroseconds flag.
func Logger(t LogPrinter) *log.Logger {
return WithPrefix(t, "")
}