kynefuk / 課題2

kadai2/kynefuk/.gitignore

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+# Created by https://www.toptal.com/developers/gitignore/api/go
+# Edit at https://www.toptal.com/developers/gitignore?templates=go
+
+### Go ###
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+### Go Patch ###
+/vendor/
+/Godeps/
+
+img
+
+# End of https://www.toptal.com/developers/gitign

kadai2/kynefuk/README.md

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+# <課題 2> io.Reader と io.Writer
+
+### io.Reader とは
+
+一連のデータ(バイト列)の読み込み処理を抽象化したインターフェース。
+読み込まれる対象データとしてバイト型の配列を受け取り、読み込んだバイト数とエラーを戻り値とする。
+
+```
+type Reader interface {
+ Read(p []byte) (n int, err error)
+}
+```
+
+### io.Writer とは
+
+一連のデータ(バイト列)の書き込み処理を抽象化したインターフェース
+書き込まれる対象データとしてバイト型の配列を受け取り、書き込んだバイト数とエラーを戻り値とする。
+
+```
+type Writer interface {
+ Write(p []byte) (n int, err error)
+}
+```
+
+## 標準パッケージでどのように使われているか
+
+データの入出力を表現する様々なパッケージで io.Reader や io.Writer が実装している。
+(標準入力を表す`os.Stdin`、標準出力を表す`os.Stdout`、ファイルの入出力を表現する`os.File`や、通信の入出力を表現する`net.Conn`など)
+
+## io.Reader と io.Writer があることでどういう利点があるのか具体例を挙げて考えてみる
+
+入力処理と出力処理の仕様をインターフェースとして定義しておくことで、様々な入出力処理を統一的に扱うことができ、プログラムの柔軟性が高くなる。
+例えば、何らかの読み込み処理を行う関数の引数の型を`io.Reader`とすることで、`io.Reader`を実装している型であれば何でも受けることができる。
+コマンドラインのの処理内容を出力する標準出力や、エラーを表示する標準エラー出力のフィールドの型として io.Writer を指定することで、テスト時に、`bytes.Buffer`などに切り替えることができ、テスト容易性を高めることができる。
+
+```
+type Command struct {
+ OutStream, ErrStream io.Writer
+}
+```

kadai2/kynefuk/cli/args.go

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+package cli
+
+import (
+ "fmt"
+)
+
+// Args represents CLI's arguments object
+type Args struct {
+ DirecTory, From, To string
+}
+
+// Validate is a validation method
+func (args *Args) Validate() error {
+ fileExtMap := createFileExtMap()
+ if _, ok := fileExtMap[args.From]; !ok {
+ return fmt.Errorf("argument of \"-f, --From\" is not valid file format. invalid format: %s", args.From)
+ }
+ if _, ok := fileExtMap[args.To]; !ok {
+ return fmt.Errorf("argument of \"-t, --To\" is not valid file format. invalid format: %s", args.To)
+ }
+
+ return nil
+}
+
+func createFileExtMap() map[string]string {
+ fileExtMap := make(map[string]string)
+ list := []string{
+ "jpg",
+ "jpeg",
+ "png",
+ "gif",
+ "bmp",
+ "tiff",
+ }
+ for _, v := range list {
+ fileExtMap[v] = ""
+ }
+ return fileExtMap
+}
+
+// NewArgs is a construcTor of Args
+func NewArgs(DirecTory, From, To string) *Args {
+ return &Args{DirecTory: DirecTory, From: From, To: To}
+}

kadai2/kynefuk/cli/args_test.go

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+package cli
+
+import (
+ "testing"
+
+ "github.com/gopherdojo/dojo8/kadai2/kynefuk/helper"
+)
+
+const dummyDir = "dummy"
+
+func TestArgs(t *testing.T) {
+ cases := []struct{ name, fromFormat, toFormat, expectedMessage string }{
+ {name: "valid arguments", fromFormat: "jpeg", toFormat: "png", expectedMessage: ""},
+ {name: "invalid from format", fromFormat: "hoge", toFormat: "jpg", expectedMessage: "argument of \"-f, --From\" is not valid file format. invalid format: hoge"},
+ {name: "invalid to format", fromFormat: "gif", toFormat: "hage", expectedMessage: "argument of \"-t, --To\" is not valid file format. invalid format: hage"},
+ }
+
+ for _, c := range cases {
+ t.Run(c.name, func(t *testing.T) {
+ args := NewArgs(dummyDir, c.fromFormat, c.toFormat)
+ actual := args.Validate()
+ if actual == nil {
+ if c.expectedMessage != "" {
+ helper.ErrorHelper(t, actual, c.expectedMessage)
+ }
+ } else if actual.Error() != c.expectedMessage {
+ helper.ErrorHelper(t, actual, c.expectedMessage)
+ }
+ })
+ }
+}

kadai2/kynefuk/cli/cli.go

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+package cli
+
+import (
+ "fmt"
+ "io"
+
+ "github.com/gopherdojo/dojo8/kadai2/kynefuk/converter"
+ "github.com/gopherdojo/dojo8/kadai2/kynefuk/walker"
+)
+
+// it represents Exit Code
+const (
+ ExitCodeOK = iota
+ ExitCodeError
+)
+
+// Command represents CLI object
+type Command struct {
+ OutStream, ErrStream io.Writer
+}
+
+// Run invoke cli main logic
+func (cli *Command) Run(directory, from, to string) int {
+ dirWalker := walker.NewWalker(from)
+ files, err := dirWalker.Dirwalk(directory)
+ if err != nil {
+ fmt.Fprintf(cli.ErrStream, "failed to read directory: %s, err: %s\n", directory, err)
+ return ExitCodeError
+ }
+
+ imgConverter := converter.NewConverter(from, to)
+ for _, file := range files {
+ dstPath := converter.ConvertExt(file, from, to)
+ if err := imgConverter.ConvertFormat(file, dstPath); err != nil {
+ fmt.Fprintf(cli.ErrStream, "failed to convert img, err: %s\n", err)
+ return ExitCodeError
+ }
+ }
+ return ExitCodeOK
+}
+
+// NewCommand is a constructor of CLI
+func NewCommand(outStream, errStream io.Writer) *Command {
+ return &Command{OutStream: outStream, ErrStream: errStream}
+}

kadai2/kynefuk/cli/cli_test.go

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+package cli
+
+import (
+ "bytes"
+ "os"
+ "strings"
+ "testing"
+
+ "github.com/gopherdojo/dojo8/kadai2/kynefuk/helper"
+)
+
+var fileExtList = []string{
+ "jpg",
+ "jpeg",
+ "png",
+ "gif",
+ "bmp",
+ "tiff",
+}
+
+func ConvertExt(filepath, to string) string {
+ return strings.Replace(filepath, ".png", to, 1)
+}
+
+func TestCLI(t *testing.T) {
+ testDir := helper.CreateTmpDir()
+ defer os.RemoveAll(testDir)
+ outStream, errStream := new(bytes.Buffer), new(bytes.Buffer)
+ command := NewCommand(outStream, errStream)
+
+ cases := []struct {
+ name string
+ directory string
+ fromFormat string
+ toFormat string
+ outStream string
+ errStream string
+ exitCode int
+ }{
+ {name: "success", directory: testDir, fromFormat: "png", toFormat: "jpg", outStream: "", errStream: "", exitCode: 0},
+ {name: "invalid directory", directory: "dummyDir", fromFormat: "jpg", toFormat: "png", outStream: "", errStream: "failed to read directory: dummyDir, err: open dummyDir: no such file or directory", exitCode: 1},
+ {name: "invalid to format", directory: testDir, fromFormat: "jpg", toFormat: "hoge", outStream: "", errStream: "failed to convert img, err: unknown format type", exitCode: 1},
+ {name: "invalid from format", directory: testDir, fromFormat: "hoge", toFormat: "png", outStream: "", errStream: "", exitCode: 1},
+ }
+
+ for _, c := range cases {
+ t.Run(c.name, func(t *testing.T) {
+ tmpFile := helper.CreateTmpFile(testDir, c.fromFormat)
+ defer os.Remove(tmpFile.Name())
+ status := command.Run(c.directory, c.fromFormat, c.toFormat)
+
+ if status != c.exitCode {
+ helper.ErrorHelper(t, c.exitCode, status)
+ }
+ if !strings.Contains(outStream.String(), c.outStream) {
+ helper.ErrorHelper(t, c.outStream, outStream.String())
+ }
+ if !strings.Contains(errStream.String(), c.errStream) {
+ helper.ErrorHelper(t, c.errStream, errStream.String())
+ }
+ })
+ }
+}

kadai2/kynefuk/converter/converter.go

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+package converter
+
+import (
+ "fmt"
+ "image"
+ "image/gif"
+ "image/jpeg"
+ "image/png"
+ "os"
+ "strings"
+
+ "golang.org/x/image/bmp"
+ "golang.org/x/image/tiff"
+)
+
+// Converter converts image file
+type Converter struct {
+ From, To string
+}
+
+// ConvertFormat converts file format
+func (converter *Converter) ConvertFormat(filepath, dst string) error {
+ file, err := os.Open(filepath)
+ if err != nil {
+ return fmt.Errorf("failed to open file. file: %s", filepath)
+ }
+ defer file.Close()
+
+ img, _, err := image.Decode(file)
+ if err != nil {
+ return fmt.Errorf("failed to decode file. file: %s", filepath)
+ }
+
+ out, err := os.Create(dst)
+ if err != nil {
+ return fmt.Errorf("failed to create output file. file: %s", dst)
+ }
+ defer out.Close()
+
+ switch converter.To {
+ case "jpg", "jpeg":
+ err = jpeg.Encode(out, img, &jpeg.Options{Quality: 100})
+ case "png":
+ err = png.Encode(out, img)
+ case "gif":
+ err = gif.Encode(out, img, &gif.Options{NumColors: 256, Quantizer: nil, Drawer: nil})
+ case "bmp":
+ err = bmp.Encode(out, img)
+ case "tiff":
+ err = tiff.Encode(out, img, nil)
+ default:
+ return fmt.Errorf("unknown format type")
+ }
+
+ return err
+}
+
+// ConvertExt converts file format extention
+func ConvertExt(filepath, from, to string) string {
+ return strings.Replace(filepath, from, to, 1)
+}
+
+// NewConverter is a Constructor of Converter
+func NewConverter(from, to string) *Converter {
+ return &Converter{From: from, To: to}
+}

kadai2/kynefuk/converter/converter_test.go

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+package converter
+
+import (
+ "os"
+
+ "github.com/gopherdojo/dojo8/kadai2/kynefuk/helper"
+
+ "testing"
+)
+
+var fileExtList = []string{
+ "jpg",
+ "jpeg",
+ "png",
+ "gif",
+ "bmp",
+ "tiff",
+}
+
+const testDirPath = "../testdata"
+
+func TestConverter(t *testing.T) {
+ tmpDir := helper.CreateTmpDir()
+ defer os.RemoveAll(tmpDir)
+
+ // from→toに画像変換できているかテスト
+ for _, from := range helper.FileExtList {
+ for _, to := range helper.FileExtList {
+ tmpFile := helper.CreateTmpFile(tmpDir, from)
+ defer os.Remove(tmpFile.Name())
+ imgConverter := NewConverter(from, to)
+ err := imgConverter.ConvertFormat(tmpFile.Name(), ConvertExt(tmpFile.Name(), from, to))
+ if err != nil {
+ t.Errorf("failed to test. error: %s", err)
+ }
+ exists := helper.Exists(ConvertExt(tmpFile.Name(), from, to))
+ if !exists {
+ t.Errorf("want true, but got %v", exists)
+ }
+ }
+ }
+}

kadai2/kynefuk/go.mod

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+module github.com/gopherdojo/dojo8/kadai2/kynefuk
+
+go 1.14
+
+require golang.org/x/image v0.0.0-20200618115811-c13761719519

kadai2/kynefuk/go.sum

@@ -0,0 +1,4 @@
+github.com/gopherdojo/dojo8 v0.0.0-20200703052727-6a79d18126bf h1:lpYevjFQMxI5VNBc3WXV6Z5pDDrdppdDKwmeBoyt5BE=
+golang.org/x/image v0.0.0-20200618115811-c13761719519 h1:1e2ufUJNM3lCHEY5jIgac/7UTjd6cgJNdatjPdFWf34=
+golang.org/x/image v0.0.0-20200618115811-c13761719519/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=