Merge pull request #24 from youta-t/feature/#20/text-matcher

add Text matcher

general.go

@@ -8,6 +8,7 @@ import (
 	"reflect"
 	"strings"
 
+	"github.com/sergi/go-diff/diffmatchpatch"
 	"github.com/youta-t/its/itskit"
 	"github.com/youta-t/its/itskit/itsio"
 )
@@ -561,3 +562,90 @@ func Pointer[T any](m Matcher[T]) Matcher[*T] {
 		m: m,
 	}
 }
+
+type textMatcher struct {
+	label itskit.Label
+	want  string
+}
+
+func (tm textMatcher) Match(got string) itskit.Match {
+	dmp := diffmatchpatch.New()
+	var diff []diffmatchpatch.Diff
+	{
+		a, b, dmpStrings := dmp.DiffLinesToChars(tm.want, got)
+		diff = dmp.DiffMain(a, b, false)
+		diff = dmp.DiffCharsToLines(diff, dmpStrings)
+		diff = dmp.DiffCleanupSemantic(diff)
+	}
+
+	message := new(strings.Builder)
+	message.WriteString(tm.label.String())
+	message.WriteString("\n")
+
+	unmatch := 0
+	for _, d := range diff {
+		header := "      | "
+		switch d.Type {
+		case diffmatchpatch.DiffDelete:
+			unmatch += 1
+			header = "    - | "
+		case diffmatchpatch.DiffInsert:
+			unmatch += 1
+			header = "    + | "
+		default:
+		}
+
+		lines := strings.SplitAfter(d.Text, "\n")
+		if len(lines) == 1 {
+			if len(d.Text) == 0 {
+				continue
+			}
+			message.WriteString(header)
+			message.WriteString(d.Text)
+			message.WriteString("\n")
+			continue
+		}
+		for _, l := range lines[:len(lines)-1] {
+			if l == "\n" {
+				message.WriteString(header[:len(header)-1])
+				message.WriteString("\n")
+				continue
+			}
+			message.WriteString(header)
+			message.WriteString(l)
+		}
+	}
+
+	return itskit.NewMatch(
+		unmatch == 0,
+		message.String(),
+	)
+}
+
+func (tm textMatcher) Write(w itsio.Writer) error {
+	if err := tm.label.Write(w); err != nil {
+		return err
+	}
+	in := w.Indent()
+	if err := in.WriteStringln(tm.want); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (tm textMatcher) String() string {
+	return itskit.MatcherToString(tm)
+}
+
+// Text returns a matcher for a long text.
+//
+// When it get unmatch, it shows diff of text.
+func Text(want string) Matcher[string] {
+	cancel := itskit.SkipStack()
+	defer cancel()
+
+	return textMatcher{
+		label: itskit.NewLabelWithLocation("(+ = got, - = want)"),
+		want:  want,
+	}
+}

general_test.go

@@ -449,3 +449,67 @@ func ExamplePointer() {
 	// ✘ /* got */ nil is not nil,		--- @ ./general_test.go:444
 	//     ✘ /* got */ ?? == /* want */ 42		--- @ ./general_test.go:444
 }
+
+func ExampleText_multibytes() {
+	// "風景" (純銀もざいく; 山村暮鳥): https://www.aozora.gr.jp/cards/000136/files/52348_42039.html
+	its.Text(`
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+かすかなるむぎぶえ
+いちめんのなのはな
+`).Match(`
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+いちめんのなのはな
+ひばりのおしやべり
+いちめんのなのはな
+`).OrError(t)
+	// Output:
+	// ✘ (+ = got, - = want)		--- @ ./general_test.go:455
+	//       |
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//       | いちめんのなのはな
+	//     - | かすかなるむぎぶえ
+	//     + | ひばりのおしやべり
+	//       | いちめんのなのはな
+}
+
+func ExampleText_ascii() {
+	// London Bridge Is Falling Down
+	its.Text(`
+Build it up with bricks and mortar,
+Bricks and mortar, bricks and mortar,
+Build it up with bricks and mortar,
+My fair lady.
+`).Match(`
+Build it up with iron and steel,
+Iron and steel, iron and steel,
+Build it up with iron and steel,
+My fair lady.
+`).OrError(t)
+	// Output:
+	//
+	// ✘ (+ = got, - = want)		--- @ ./general_test.go:493
+	//       |
+	//     - | Build it up with bricks and mortar,
+	//     + | Build it up with iron and steel,
+	//     - | Bricks and mortar, bricks and mortar,
+	//     + | Iron and steel, iron and steel,
+	//     - | Build it up with bricks and mortar,
+	//     + | Build it up with iron and steel,
+	//       | My fair lady.
+}

go.mod

@@ -3,3 +3,5 @@ module github.com/youta-t/its
 go 1.21
 
 require golang.org/x/mod v0.14.0
+
+require github.com/sergi/go-diff v1.3.1

go.sum

@@ -1,2 +1,20 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sergi/go-diff v1.3.1 h1:xkr+Oxo4BOQKmkn/B9eMK0g5Kg/983T9DqqPHwYqD+8=
+github.com/sergi/go-diff v1.3.1/go.mod h1:aMJSSKb2lpPvRNec0+w3fl7LP9IOFzdc9Pa4NFbPK1I=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
 golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=