experiment with some tests

internal/logging/logging.go

@@ -0,0 +1,35 @@
+package logging
+
+import (
+	"log"
+	"os"
+)
+
+type Logger struct {
+	infoLogger  *log.Logger
+	errorLogger *log.Logger
+	eventLogger *log.Logger
+}
+
+func NewLogger() *Logger {
+	return &Logger{
+		infoLogger:  log.New(os.Stdout, "", 0),
+		errorLogger: log.New(os.Stderr, "", 0),
+		eventLogger: log.New(os.Stdout, "", log.Ldate|log.Ltime),
+	}
+}
+
+// Infof writes an info message to stdout
+func (l *Logger) Infof(format string, v ...interface{}) {
+	l.infoLogger.Printf(format, v...)
+}
+
+// Errorf writes an error message to stderr
+func (l *Logger) Errorf(format string, v ...interface{}) {
+	l.errorLogger.Printf(format, v...)
+}
+
+// Eventf writes an event with timestamp to stdout
+func (l *Logger) Eventf(format string, v ...interface{}) {
+	l.eventLogger.Printf(format, v...)
+}

internal/logging/logging_test.go

@@ -0,0 +1,41 @@
+package logging
+
+import (
+	"bytes"
+	"log"
+	"regexp"
+	"testing"
+)
+
+const dateFormatPattern = `[\d]{4}/[\d]{2}/[\d]{2} [\d]{2}:[\d]{2}:[\d]{2}`
+
+var l = NewLogger()
+
+var logTests = []struct {
+	logger      *log.Logger
+	test        func()
+	expectation string
+}{
+	{l.infoLogger, func() { l.Infof("Info message no. %d", 1) }, "Info message no. 1\n"},
+	{l.infoLogger, func() { l.Infof("Info message no. %d with a string %s\n", 2, "appended to it") }, "Info message no. 2 with a string appended to it\n"},
+	{l.errorLogger, func() { l.Errorf("Error message") }, "Error message\n"},
+	{l.errorLogger, func() { l.Errorf("Error message\n") }, "Error message\n"},
+	{l.eventLogger, func() { l.Eventf("Event message") }, dateFormatPattern + " Event message\n"},
+}
+
+func TestLogging(t *testing.T) {
+	for i, tt := range logTests {
+		actual := captureOutput(tt.logger, tt.test)
+		matcher := regexp.MustCompile(tt.expectation)
+		if !matcher.Match([]byte(actual)) {
+			t.Fatalf("[%d] Wrong message logged!: %s", i, actual)
+		}
+	}
+}
+
+func captureOutput(logger *log.Logger, f func()) string {
+	var buf bytes.Buffer
+	logger.SetOutput(&buf)
+	f()
+	return buf.String()
+}