feat: unified diff

bromide.go

@@ -62,7 +62,7 @@ func Snapshot[K comparable](t *testing.T, item K) {
 		diff := internal.Diff(existing.String(), incoming)
 
 		t.Log("snapshot mismatch")
-		t.Log(diff)
+		t.Log("\n" + diff)
 		t.Log("to update snapshots run `bromide review`")
 
 		os.WriteFile(pendingPath, []byte(incoming), 0644)

go.mod

@@ -3,12 +3,14 @@ module github.com/cobbinma/bromide
 go 1.22.0
 
 require (
+	github.com/davecgh/go-spew v1.1.1
+	github.com/hexops/gotextdiff v1.0.3
 	github.com/hexops/valast v1.4.4
 	github.com/sergi/go-diff v1.3.1
 )
 
 require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/andreyvit/diff v0.0.0-20170406064948-c7f18ee00883 // indirect
 	github.com/google/go-cmp v0.5.9 // indirect
 	golang.org/x/mod v0.7.0 // indirect
 	golang.org/x/sys v0.3.0 // indirect

go.sum

@@ -1,3 +1,5 @@
+github.com/andreyvit/diff v0.0.0-20170406064948-c7f18ee00883 h1:bvNMNQO63//z+xNgfBlViaCIJKLlCJ6/fmUseuG0wVQ=
+github.com/andreyvit/diff v0.0.0-20170406064948-c7f18ee00883/go.mod h1:rCTlJbsFo29Kk6CurOXKm700vrz8f0KW0JNfpkRJY/8=
 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=

internal/diff.go

@@ -1,13 +1,38 @@
 package internal
 
 import (
-	"github.com/sergi/go-diff/diffmatchpatch"
+	"fmt"
+	"strings"
+
+	"github.com/hexops/gotextdiff"
+	"github.com/hexops/gotextdiff/myers"
 )
 
 func Diff(old, new string) string {
-	dmp := diffmatchpatch.New()
+	edits := myers.ComputeEdits("current", old, new)
+	diff := fmt.Sprint(gotextdiff.ToUnified("current", "incoming", old, edits))
+
+	out := ""
+	for _, line := range strings.Split(diff, "\n") {
+		green := "\x1b[32m"
+		red := "\x1b[31m"
+		reset := "\x1b[0m"
+
+		addition := strings.HasPrefix(line, "+")
+		subtraction := strings.HasPrefix(line, "-")
+
+		l := ""
+		switch {
+		case addition:
+			l = green + line
+		case subtraction:
+			l = red + line
+		default:
+			l = reset + line
+		}
 
-	diffs := dmp.DiffMain(old, new, true)
+		out = out + l + "\n"
+	}
 
-	return dmp.DiffPrettyText(diffs)
+	return out
 }