Kadai4 uobikiemukot

kadai4/uobikiemukot/fortune/cmd/server/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gopherdojo/dojo4/kadai4/uobikiemukot/fortune"
+)
+
+func main() {
+	clock := fortune.ClockFunc(func() time.Time {
+		return time.Now()
+	})
+	f := fortune.Fortune{Clock: clock}
+
+	http.HandleFunc("/", f.Handler)
+	http.ListenAndServe(":8080", nil)
+}

kadai4/uobikiemukot/fortune/fortune.go

@@ -0,0 +1,96 @@
+package fortune
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"time"
+)
+
+// index of values
+const (
+	excellent = iota
+	great
+	good
+	bad
+)
+
+var values = []string{
+	"大吉", "中吉", "小吉", "凶",
+}
+
+// Clock return current time
+type Clock interface {
+	Now() time.Time
+}
+
+// ClockFunc is an adapter to implement Clock interface
+type ClockFunc func() time.Time
+
+// Now calls f()
+func (f ClockFunc) Now() time.Time {
+	return f()
+}
+
+// Fortune implement Clock interfate
+type Fortune struct {
+	Clock Clock
+	Err error
+}
+
+// Result is type for JSON encode/decode
+type Result struct {
+	Fortune string `json:"fortune"`
+}
+
+// Encode converts Result into JSON string
+func Encode(r Result) (string, error) {
+	b := bytes.Buffer{}
+	e := json.NewEncoder(&b)
+
+	err := e.Encode(&r)
+	if err != nil {
+		return "", err
+	}
+
+	return string(b.Bytes()), nil
+}
+
+// Decode converts JSON string into Result
+func Decode(s string) (Result, error) {
+	b := bytes.NewBufferString(s)
+	d := json.NewDecoder(b)
+
+	var r Result
+	err := d.Decode(&r)
+	if err != nil {
+		return r, err
+	}
+
+	return r, nil
+}
+
+// Handler http.HandleFunc implementation
+func (f *Fortune) Handler(w http.ResponseWriter, r *http.Request) {
+	var res Result
+	now := f.Clock.Now()
+
+	if now.Month() == time.January && (1 <= now.Day() && now.Day() <= 3) {
+		// always return excellent
+		res.Fortune = values[excellent]
+	} else {
+		// random pick up
+		rand.Seed(now.Unix())
+		i := rand.Int() % len(values)
+		res.Fortune = values[i]
+	}
+
+	json, err := Encode(res)
+	if err != nil {
+		f.Err = err
+	} else {
+		fmt.Fprintf(w, json)
+	}
+}

kadai4/uobikiemukot/fortune/fortune_test.go

@@ -0,0 +1,128 @@
+package fortune_test
+
+import (
+	"bytes"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/gopherdojo/dojo4/kadai4/uobikiemukot/fortune"
+)
+
+// dummyWriter implement http.ResponseWriter
+type dummyWriter struct {
+	buf bytes.Buffer
+}
+
+func (d *dummyWriter) Header() http.Header {
+	return nil
+}
+
+func (d *dummyWriter) Write(b []byte) (int, error) {
+	return d.buf.Write(b)
+}
+
+func (d *dummyWriter) WriteHeader(code int) {
+}
+
+// mockWriter creates dummyWriter from bytes.Buffer
+func mockWriter(t *testing.T, b bytes.Buffer) dummyWriter {
+	t.Helper()
+	return dummyWriter{buf: b}
+}
+
+// mockClock creates fortune.ClockFunc from date string
+func mockClock(t *testing.T, s string) fortune.ClockFunc {
+	t.Helper()
+
+	now, err := time.Parse("2006/01/02", s)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return fortune.ClockFunc(func() time.Time {
+		return now
+	})
+}
+
+func parse(t *testing.T, s string) string {
+	t.Helper()
+
+	r, err := fortune.Decode(s)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return r.Fortune
+}
+
+func TestHandler_Success(t *testing.T) {
+	w := mockWriter(t, bytes.Buffer{})
+
+	cases := map[string]struct {
+		writer *dummyWriter
+		clock  fortune.Clock
+	}{
+		"1900/01/01": {
+			writer: &w,
+			clock:  mockClock(t, "1900/01/01"),
+		},
+		"2000/02/29": {
+			writer: &w,
+			clock:  mockClock(t, "2000/02/29"),
+		},
+		"2020/12/19": {
+			writer: &w,
+			clock:  mockClock(t, "2020/12/19"),
+		},
+	}
+
+	for _, c := range cases {
+		c.writer.buf.Reset()
+
+		f := &fortune.Fortune{Clock: c.clock}
+		f.Handler(c.writer, nil)
+
+		if f.Err != nil {
+			t.Errorf("error occurred: %s", f.Err)
+		}
+	}
+}
+
+func TestHandler_SpecialDate(t *testing.T) {
+	w := mockWriter(t, bytes.Buffer{})
+
+	cases := map[string]struct {
+		writer *dummyWriter
+		clock  fortune.Clock
+		msg    string
+	}{
+		"2019/01/01": {
+			writer: &w,
+			clock:  mockClock(t, "2019/01/01"),
+			msg:    "大吉",
+		},
+		"2020/01/02": {
+			writer: &w,
+			clock:  mockClock(t, "2020/01/02"),
+			msg:    "大吉",
+		},
+		"2021/01/03": {
+			writer: &w,
+			clock:  mockClock(t, "2021/01/03"),
+			msg:    "大吉",
+		},
+	}
+
+	for _, c := range cases {
+		c.writer.buf.Reset()
+
+		f := &fortune.Fortune{Clock: c.clock}
+		f.Handler(c.writer, nil)
+
+		r := parse(t, c.writer.buf.String())
+		if r != c.msg {
+			t.Errorf("want:%s but got:%s\n", c.msg, r)
+		}
+	}
+}

kadai4/uobikiemukot/fortune/go.mod

@@ -0,0 +1 @@
+module github.com/gopherdojo/dojo4/kadai4/uobikiemukot/fortune