Extract out log package

internal/log/log_test.go

@@ -0,0 +1,121 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
+package log
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+	"testing"
+)
+
+// regexp for timestamps
+const (
+	rgxdate         = `[0-9][0-9][0-9][0-9]/[0-9][0-9]/[0-9][0-9]`
+	rgxtime         = `[0-9][0-9]:[0-9][0-9]:[0-9][0-9]`
+	rgxmicroseconds = `\.[0-9][0-9][0-9][0-9][0-9][0-9]`
+)
+
+type tester struct {
+	desc        string
+	message     string
+	wantPattern string // regexp that log output must match
+}
+
+func TestLoggerInfo(t *testing.T) {
+	tests := []tester{
+		{
+			desc:        "without trailing newline, logger adds newline",
+			message:     "hello, world!",
+			wantPattern: fmt.Sprintf("^%s %s%s INFO: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+		{
+			desc:        "with trailing newline, logger preserves newline",
+			message:     "hello, world!\n",
+			wantPattern: fmt.Sprintf("^%s %s%s INFO: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+	}
+
+	for _, tc := range tests {
+		var buf bytes.Buffer
+		logger := NewLogger(&buf)
+
+		logger.Info(tc.message)
+
+		got := buf.String()
+		matched, err := regexp.MatchString(tc.wantPattern, got)
+		if err != nil {
+			t.Fatal("pattern did not compile:", err)
+		}
+		if !matched {
+			t.Errorf("logger.info(%q) outputted %q, should match pattern %q",
+				tc.message, got, tc.wantPattern)
+		}
+	}
+}
+
+func TestLoggerWarn(t *testing.T) {
+	tests := []tester{
+		{
+			desc:        "without trailing newline, logger adds newline",
+			message:     "hello, world!",
+			wantPattern: fmt.Sprintf("^%s %s%s WARN: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+		{
+			desc:        "with trailing newline, logger preserves newline",
+			message:     "hello, world!\n",
+			wantPattern: fmt.Sprintf("^%s %s%s WARN: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+	}
+
+	for _, tc := range tests {
+		var buf bytes.Buffer
+		logger := NewLogger(&buf)
+
+		logger.Warn(tc.message)
+
+		got := buf.String()
+		matched, err := regexp.MatchString(tc.wantPattern, got)
+		if err != nil {
+			t.Fatal("pattern did not compile:", err)
+		}
+		if !matched {
+			t.Errorf("logger.info(%q) outputted %q, should match pattern %q",
+				tc.message, got, tc.wantPattern)
+		}
+	}
+}
+
+func TestLoggerError(t *testing.T) {
+	tests := []tester{
+		{
+			desc:        "without trailing newline, logger adds newline",
+			message:     "hello, world!",
+			wantPattern: fmt.Sprintf("^%s %s%s ERROR: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+		{
+			desc:        "with trailing newline, logger preserves newline",
+			message:     "hello, world!\n",
+			wantPattern: fmt.Sprintf("^%s %s%s ERROR: hello, world!\n$", rgxdate, rgxtime, rgxmicroseconds),
+		},
+	}
+
+	for _, tc := range tests {
+		var buf bytes.Buffer
+		logger := NewLogger(&buf)
+
+		logger.Error(tc.message)
+
+		got := buf.String()
+		matched, err := regexp.MatchString(tc.wantPattern, got)
+		if err != nil {
+			t.Fatal("pattern did not compile:", err)
+		}
+		if !matched {
+			t.Errorf("logger.info(%q) outputted %q, should match pattern %q",
+				tc.message, got, tc.wantPattern)
+		}
+	}
+}